The Tabanidae (Horseflies) of Minnesota with Special Reference to Their Biologies and Taxonomy

University of Minnesota Agricultural Experiment Station

The Tabanidae (Horseflies) of Minnesota With Special Reference to Their Biologies and Taxonomy

Cornelius B. Philip Division of Entomology and Economic Zoology

UNIVERSITY FARM, ST. PAUL CONTENTS

Part One Page I. Introduction 3 Historical 3 Economic status 5 Disease transmission 0

II. Biological discussion 12 Representative life-history 12 Early stages of other species 25 Bionomics of adults 39 Seasonal and geographic distribution 47 Climate and topography of Minnesota 63 Environmental resistance and tabanid population 64 Physical factors 65 Biotic factors 67 Preventive and protective measures 69

III. Literature cited 7o

Part Two

IV. Systematic treatise 77 Taxonomy of adults 77 Keys to immature stages 79 Summary 125

V. Taxonomic references '7 THE TABANIDAE (HORSEFLIES) OF MINNE- SOTA WITH REFERENCE TO THEIR BIOLOGIES AND TAXONOMY CORNELIUS B. PHILIP* PART ONE I. INTRODUCTION Of all the blood-sucking insects, the mosquitoes and perhaps the tsetse flies in Africa alone surpass the Tabanidae in economic importance when all factors are considered. Notwithstanding the omni- presence of horseflies in all parts of Minnesota, and their legion in some sections of the north during June and early July, very little information is at hand concerning the tabanid species involved or regarding their habits and the manner of their development. Yet such data are almost prerequisite to rational measures for alleviating this scourge. The family includes the flies popularly referred to as horseflies, gad- flies, breezeflies, mooseflies, bulldogs, klegs, deerflies, earflies, and so on, according to the locality. Most of these names are restricted in use to the larger horseflies of the genus Tabamts. Greenhead is a term applied in this state to Tabamts lineola, and in the Northwest to T. septentrionalis, altho different species of the genus go by that name in other parts of the United States. Bulldogs and mooseflies are local names used in the north in referring to the species of the affinis group of Tabamts, a group of red-sided horseflies that will be discussed later. The smaller flies of the genus Chrysops are commonly known as deerflies or earflies. In some sections of the north woods they are called pineflies because of their particular abundance in and about the edges of the forests and woods. The species of these two genera are the only horseflies of importance occurring in the state. Haematopota americana is reported by Cameron (1918)1 to settle on both stock and people in Saskatchewan, and has been so observed by the writer in Montana, but in Minnesota it is of very infrequent occurrence, being found in the northern part of the state only, where it is of no consequence economically.

HISTORICAL That the Tabanidae were prominent among the problems of the early settlers in the state is well shown by the attention they received from Dr. 0. Lugger, the first state entomologist of Minnesota. In his * Now with the U. S. Public Health Service, Hamilton, Mont. 1 Dates in parenthesis refer to titles in the list of literature cited at the end of Part I. 4 MINNESOTA TECHNICAL BULLETIN 80

second report (1896), he mentions the trouble caused by these pests in various parts of the state and gives a very vivid account of their prevalence. C. V. Riley (1887), in referring to tabanids as a pest of stock, states that "in parts of the Mississippi Valley it is impossible to work horses in midsummer without protective covering, and in more northern regions even cattle have to be covered." When flies are abundant, not only the domesticated stock suffer because of their insatiable appetite for blood, but in the words of Lugger (loc. cit.), "moose and deer lose all fear of man and plunge into rivers and lakes to escape their attacks; they soon become very poor, as they have no rest to feed excepting at night." His meager data relative to life histories and to the species concerned afford a good index to the status of the study of the family at the beginning of this century. Washburn (1905) discusses the family in his report on the Diptera of Minnesota, summarizing in brief the limited information concerning the habits and biologies of horseflies at that time. His remarks are supplemented with a list of 20 species taken in the state. C. W. Howard, in the summer of 1914, again initiated a study of the Taban- idae. If was continued during the following two years as a project of the Minnesota Agricultural Experiment Station, with emphasis on the possibilties of transmission of swamp fever of horses. A brief report of his preliminary work will be mentioned more specifically later. A series of unfavorable seasons, and lack of funds, caused the study to be discontinued. Because of continued annoyance from the pests, the Tabanidae were again made the subject of an experiment station project in 1924. It is interesting to note the similarity in the history of the horsefly project in Louisiana, where the probable dissemination of anthrax, instead of swamp fever, enters in to make doubly urgent the need for a study of the flies as stock pests in that state. Following productive preliminary studies by Professor Hine, the project was discontinued until reopened in 1920 by Jones and Bradley. This study is in line with a project already established in Minnesota, therefore, and was suggested to the writer by W. A. Riley. To him and to other members of the Division of Entomology of the University the writer is deeply grateful for numerous suggestions and aids during the course of the work. J. S. Hine has identified or confirmed a few of the more difficult specimens noted in the systematic portion of this paper, and thanks are also due J. M. Aldrich and A. B. Gahan, of the National Museum and the Bureau of Entomology, respectively, for determinations of parasites reared during the investigation: A. K. Fisher, of the United States Bureau of Biological Survey, has generously sup- plied a list of the tabanids consumed by birds as compiled in their studies up to April, 1925. The study has also been greatly facilitated THE TABANIDAE OF MINNESOTA 5 through exchange of pertinent species with many persons of whom space does not permit full mention. Acknowledgments would not be complete without mention of the continuous invaluable and sympathetic aid afforded by my wife during the accumulation of the data and their subsequent presentation.

ECONOMIC STATUS The Tabanidae occupy a position more or less overlapping the fields embracing economic insects of purely agricultural importance and those of pathological interest as affecting both man and animals. No end of problems are thus continually arising of a varied nature which their cosmopolitan distribution enhances. Some reference has already been given to the economic importance of tabanids in the earlier history of the state. They constitute the worst pest of stock we have in the northern sections, where they fairly swarm for about four weeks during the early part of the summer. The severity of an outbreak can be appreciated only by actual observation. Similar abundance apparently occurs in Louisiana, of which Newell (see Hine, 1906) says "It is doubtful if any of the scientists who have touched, in their publications, upon the importance of these insects or upon their role in the dissemination of disease have had even a remote conception of the enormous numbers of these flies which at times infest certain of the coast and alluvial sections of Louisiana." Hine (1907), speaking of visiting a heavily infested swamp near Baton Rouge, mentions that . . . since that time (I) have had a much better idea of the injury that may be caused by horseflies than I ever had before. One would fail in an attempt to describe the exact conditions for to be fully appreciated they must be seen." In infested sections of Minnesota not only is diversified farming hampered, but stock raising and dairying are rendered extremely difficult. Howard (1916) states that "in places where farmers are trying to build up dairy farms, the presence of these flies has reduced the milk supply as much as 66 per cent in two weeks and in three nearly Ioo per cent." It is realized that derivation of statistics of this type are extremely difficult, and in a good many cases the statements of the dairymen and farmers themselves must be relied upon solely for judg- ment of the factors involved. In many parts of the state, however, dairying is the chief agricultural pursuit, especially where the land is more suited to grazing and pasture than to cultivation. A considerable portion of the northern half of the state consists of muskeg, a boggy type of land, interspersed with numerous lakes and open bodies of water. Not only is this a difficult type of land to farm, but it furnishes an idehl environment for the breeding of horseflies, and in such numbers as to make one of the best suited types of farming, 6 MINNESOTA TECHNICAL BULLETIN 80 namely dairying, unprofitable or even impossible. In parts of Roseau County dairying has had to be discontinued during certain seasons because of horsefly activities. An extreme case of this nature is quoted from Portschinsky (see Fraser, 1920), to the effect that, in northern Russia, agricultural operations must be carried on at night in the summer time, and in parts of Siberia, such as the shores of the River Om, settlers have been compelled to abandon the zone infested by horseflies because of their abundance. Trips were made by the writer to International Falls during the summer of 1924 and to Roseau County in 1925 for the purpose of making observations during the period when the horseflies were most abundant. The day previous to arrival at International Falls was the first warm day that had occurred following a prolonged cold spell in an abnormally late spring, and the horseflies were just beginning to appear. By the end of three days they had increased to such an extent that they were abundant everywhere about the farms on the outskirts of the town and especially near and in the forest. They were out by eight o'clock in the morning in numbers sufficient to drive the pasturing stock to the barns on the run and the animals could not be driven from such shelter before the evening brought respite from the persistent attack of their voracious persecutors. Even short-haired dogs were so annoyed as to be constantly snapping at the flies. The trip to Roseau County in the middle of July, 1925, was made apparently just past the peak of horsefly abundance. They were still very annoying to the residents, however, and furnished an interesting comparison, both seasonally and environmentally, with the observations made earlier in the season the previous year at International Falls. The general consensus of opinion at both places seemed to be that horseflies were not so abundant as they were 15 or 20 years ago, in spite of the fact that one had difficulty in conceiving of worse conditions that in those sections during the maximum of the horsefly flight. Hungry as they may be, both horses and cattle will spend their time restlessly moving about and fighting flies if kept exposed in a field without shelter. It is evident that they suffer severely under such circumstances. There is a very large and sometimes overlooked, insidious dissipation of energies in the animals from the annoyance caused by these flies and the resulting nervous reaction, in addition to a very considerable loss of blood. An animal covered with wounds , may literally appear crimson over the sides, neck, and flanks, so freely does the blood sometimes flow from the many punctures made by departed flies. The flies do not enter darkened barns to a great 'extent, and those that do are usually found at the windows trying to escape. The practice has been to keep the barn or some shelter always accessible for relief THE TABANIDAE OF MINNESOTA 7

of the stock during the fly season; some farmers even hang strips of burlap or canvas over the doorway to aid in keeping out the flies and in brushing them off the back and flanks of the animal as it enters. Cows, when swarming with flies, have been observed to lie down in the barnyards and allow the poultry to peck the flies from about the eyes and ears and other parts of the body. Horses that are being worked offer especially attractive subjects for attack, both because they are not so capable of defending themselves and because they are usually hot and sweaty. Fly nets afford little protection when the flies are numerous. Burlap neck and body coverings, and overalls split to form leg protectors, have been resorted to by some farmers when it was necessary to use a team during the hours of the day that the tabanids are on the wing; but generally, in the height of the fly season, a team is worked only during the cooler morning and evening hours. Even deaths in pastures without shelter have been authentically reported as due to the persecutions of horseflies in tormenting and running the animals to such a state of exhaustion and overheating that they succumbed. Injuries to the running animals from fences and other objects are more frequent. The Minnesota species of the genus Tabanus which cause the greatest annoyance to stock, seem to concentrate their attack about the neck, shoulders, belly, and legs of horses when any selectivity is shown at all. A cow with a maimed tail, which was tethered along the roadside near Bemidji, was watched at a time when species of both Chrysops and Tabanus were swarming all over the defenseless animal to such an extent that she had become lethargic in her response to their presence. The larger horseflies attacked the neck and shoulders and the legs to a considerable extent; the deerflies worked particularly about the head, behind the shoulders, and at the base of the tail. Both visited the udder and teats almost continuously and the inside of the hind legs seemed a favorite place to the deerflies. More restricted selection of a point of attack on the host, as noted by Patton and Cragg (1913), to vary with the species, has not been observed here C. W. Howard remarked that while an undetermined species of Tabanus observed by him attacked adult cattle more readily than calves, it nevertheless selected the skin on the sides of the belly, legs, under and between the legs, and around the nose, where he believes the skin is probably thinner. When preparing to bite, the flies place the front legs well forward, and apply the proboscis in a feeling motion over a limited area of the skin. Then the head is pressed down with a direct, steady thrust, while the mouth parts cut their way to a capillary until the base of the eyes appears to touch the skin. The flabellum is flattened over the surface in 8 MINNESOTA TECHNICAL BULLETIN 80 a position to aid in ingestion of the blood from the wound, and the antennae are raised so as to project upward. Elevation of the hind legs, as mentioned by Webb and Wells (1924) for T. punctifcr, was not noted. During the process of blood ingestion, the abdomen is kept in rapid movement of contraction and expansion, more vigorous and irregular than those observed in normal respiration. Occasionally, as the stomach fills, a drop of clear, yellowish liquid is ejected from the anus of some individuals during feeding; later a drop of blood is sometimes voided. The abdomen swells very slowly at first, but later fills out rapidly on the anterior half, which may or may not become darker in color. About 4 to 6 minutes are required for a feed to satisfaction by T. lasiophthalmus. After feeding to satisfaction, the fly may withdraw and make new stabs, apparently for the pure love of it; in one undisturbed case as many as ten punctures were made in an area of two square inches. Sometimes blood continues to flow freely from the wound, so that the exposed victim in a badly fly-infested region may be literally covered with blood from the bites of these voracious pests. This is a considerable loss but is usually not included in losses of blood attributed to tabanids, in the literature. Numerous small muscid flies, incapable of making a wound themselves, frequently gather at fresh wounds even before the horseflies are through, to lap up the blood exuding about the puncture. In the spring of 1929, the process of feeding was again watched very closely in the Bitter Root Valley, in Montana. A specimen of T. procyon lit on the back of the writer's hand and after a brief moment of exploration to find a suitable spot it settled down to pierce the skin. It was apparently unfed and in a fresh condition from the appearance of the pelage. While boring, the body was tilted at an angle until a small blood vessel was apparently tapped, when the tip of the abdomen was dropped away from the wings as the blood was pumped back into the gut. In this instance, owing to the inherent wariness of the fly, upon completion of feeding, the mouthparts were suddenly withdrawn and the fly was away almost in the same motion, altho it had not been disturbed. The flight was very heavy, owing to distention with blood. Feeding was rapid and occupied a little over 3 minutes. Cornwall and Patten (1914) reported a powerful anticoagulin in the salivary secretion of T. albimedius. Greater reaction would be expected at the site of the wound resulting from the bites of tabanids than has occurred in our experience. In instances of uninterrupted feeding that were allowed to proceed on the writer's person both with T. procyon and T. osburni, the only discomfort occurred at the time of piercing. There was no irritation during feeding, nor impulse to "scratch the THE TABANIDAE OF.MINNESOTA 9

bite" after the fly had gone. However, a certain lady of the writer's acquaintance who reported being bitten freely about the ankles in camp in Id?.ho (probably T. °shunt°, has remarked that "brown areas" were noticeable about the site of the wounds for some weeks afterward and there was some swelling at the time. Bey (1930) reports a severe per- sonal reaction after attacks by certain European tabanids, the effects of the bite lasting more than a week, as discussed in his work on the Tabanidae of Egypt. Webb and Wells (1924) mention an observation on the large T. punctifcr in which the female completed a meal in i i minutes and Io seconds and Cameron (1926) has placed repletion for medium-sized flies of T. septentrionalis at io minutes. The size of the fly and the probabilities of previous interrupted feedings together with the vascu- larity of the portion of the host attacked are obviously the deciding factors influencing the length of time required for the ingestion of a full meal of blood at any one time. Observations by the writer (1930) on several hundreds of unfed, caged mosquitoes during blood ingestion emphasized the variability of the time required for satiation among members of the same species and age feeding on different parts of the same immobilized host animal. Two deerflies were observed to satisfy themselves, apparently, in a little more than 4 minutes each, on the tail-less cow near Bemidji previously mentioned; both attacked at the base of the tail where they could not be dislodged by their host. The cow referred to appeared to be the only one in the immediate neighborhood, and had become so passive to attack that quantities of both horseflies and deerflies were caught by hand at this time. Adults have been taken off animals most readily in this manner because of the intolerance the majority of the animals dis- play for the use of a net around them. Fraser (loc. cit.) has drawn a lurid picture of Russian conditions at a time when the tabanids were even a worse pest than he had ever observed the tsetse flies to be in Africa. Over a hundred could be seen on a person at one time with hundreds flying around. Conditions are seldom as extreme as that in northern Minnesota, but during early July 40 to 50 flies on an animal under ordinary circumstances are not an exag- geration, with several times that number in the surrounding atmosphere. Tabanus inetabolus and T. lasiophthalmus outnumbered the other species in 1925 in Roseau County two to one, while T. astutus was observed to be the first to appear in numbers at International Falls in June, 1924. Altho they seldom complete an uninterrupted meal, about the same number of flies are on an animal at any one time between 7:30 and 8.00 a.m. to 5:30 and 6:00 p.m. during the height of the flight. Assuming that about as many deerflies visit the animals as do the larger tabanids, T. affinis and T. stygius, it is estimated an average of 10 cc. of blood 10 MINNESOTA TECHNICAL BULLETIN 80 may be withdrawn by about ioo tabanids in feeding to satiety. Since we have observed specimens of C. initis and T. lasiophthalmus to satisfy themselves in 4 to 6 minutes, 10 minutes would be a liberal allowance on the average. Assuming, therefore, that during that time 50 flies will have taken not less than 5 cc. of blood from an exposed animal, that animal would stand to lose a minimum of 300 cc. during the period of activity of the flies in a sunny day in early July in the north, in addition to the blood exuding from fresh wounds, which is a liberal amount in itself. This loss of blood is at the rate of about a quart during 3 days, on a conservative basis. One can appreciate the ordeal unsheltered stock undergo in pastures at such periods.

DISEASE TRANSMISSION It is not alone as tormentors of domestic stock that the Tabanidae have come into prominence. They have been definitely incriminated as the carriers of certain important diseases of man and animals. Because of the blood-sucking propensities of the females, the conditions are well adapted for the mechanical transmission or inoculation of disease- producing organisms. Being rather large in size and having strong, piercing mouth parts, the flies are seldom allowed to complete a meal undisturbed, owing to the annoyance experienced by the host. The chances of transmitting infection from a diseased to a healthy host are therefore good, in view of the interrupted or intermittent type of attack by the flies and the "huddling together" of harassed stock. Furthermore, sick animals will frequently offer less retaliation to attack, as pointed out by Cameron (1926), and the chances of a horsefly becoming contaminated are therefore increased. The excess of blood about wounds and the fecal ejections of fed flies are all potential conditions for the spread of infections. Anthrax, an important bacterial disease to which man and many herbivorous animals are susceptible, has long been suspected of being disseminated by tabanids. Mitzmain (1914) and Morris (1918) have demonstrated experimentally the transfer of the bacilli of this disease to normal guinea pigs by means of the bite of captive Tabanus after an interrupted feeding on an infected animal during bacteremia. Recently, Niesculz and Huber (1928) have proved horseflies to be potential vectors of several diseases including blackleg and anthrax. Anaplasmosis of cattle has also recently been transferred experimentally from infected to healthy animals at the Oklahoma Agricul- tural Experiment Station by Sanborn, Stiles, and Moe, using 3 species of tabanids. Other investigations have also proved the dissemination by tabanids of trypanosome diseases by direct transfer in a manner similar to that THE TABANIDAE OF MINNESOTA ii

demonstrated in the early investigations of sleeping sickness in Africa.. Unlike the tsetse flies, however, horseflies have not as yet been implicated as essential hosts of the pathogenic flagellates. Outstanding among this work is that of Mitimain (1913) on the transmission of surra, a trypanosome disease of stock in the Philippines and in other countries. Other trypanosome diseases of animals transferred by tabanids are nagana, souma, mal de caderas, and mbori. Jegen (1924) has described Crithidia haematopotae from Haematopota pluvialis in Europe, which has no known disease connections, and other similar instances are on record. In connection with diseases affecting human beings, Francis and •Mayne (1922) have implicated Chrysops discalis in the transfer of the "deerfly fever" of Utah and other western states on the basis of case reports and of experimental evidence. Increasing information on the distribution of this disease has shown that this deerfly probably plays an important role in the dissemination of the "fever" only in certain restricted areas in the western United States. Other tabanids are probably capable of mechanical transfer of the malady.2 Tularaemia, as it is now universally known, has been reported from almost every state in the Union and cases have recently been recorded from certain countries in northern Europe. The periodic fluctuations of the numbers of rodent hosts, particularly rabbits, are such that an epidemic of the disease could conceivably be very much enhanced by tabanids. The abundant species of horseflies of obscure habits mentioned later, undoubtedly obtain blood from some source, altho they are seldom or never seen about stock. Even reptiles and amphibians are known to be favored by certain species of exotic tabanids. Rodents and small game may be subject to the attacks of some of our obscure forms, so the role of horseflies in aggravating an endemic focus of this disease may be more important than we now assume. Indirectly, they could thus contribute to human infection by increasing the numbers of infected animals, the handling of which constitutes the usual source of the disease in persons at present. Leiper (1913) and the Connals (1922) have demonstrated the development in two Chrysops spp. of the larval stages of Loa loa Guyot, a filarial worm parasitic in man in Africa. This is the only apparent case in which tabanids are known to act as intermediate hosts of parasites. Ferguson (1927) has referred to the "strong suspicion" that members of this family are concerned as vectors of the nematode disease of cattle in Australia known as onchocerciasis.

2 Experiments subsequently performed at the United States Public Health Service Laboratory, Hamilton, Montana, have shown two local species of Tabanus to be capable of such transfer. 12 MINNESOTA TECHNICAL BULLETIN 80

Brumpt (1927) charges tabanids with experimental, mechanical transfer of the spirochaete causing infectious jaundice, and with car- riage of the eggs of Dermatobia cyaniventris, a South American bot-fly whose larvae infest certain domestic stock and not infrequently man. Dourine and equine infectious anemia can be transferred by horseflies. Scott (1920) has shown T. septcntrionalis to be involved in the mechanical dissemination of the latter disease or "swamp fever" of the horse, investigations of which were also initiated at the Minnesota station by Howard (1917). While this disease has been known in Minne- sota for some time and was even at one time epidemic, the chief economic consideration with the horseflies in this state has been one of• relationship to farm and dairying operations directly. The immediate object of this preliminary study has been, first, to ascertain definitely what species occur in Minnesota and their relative importance and distribution, and second, to initiate a study of the life - histories and bionomics of the pests in this region. It is hoped to thus clear the way toward a better understanding of the horsefly problem in the state, looking toward alleviation from the scourge.

II. BIOLOGICAL DISCUSSION Representative Life History Horseflies, as with a great many other insects of medical and veterinary importance, are troublesome as adults. Unlike most other economic insects on the farm, comparatively little is known of their early development. The farmer generally knows that cabbage worms and cutworms turn into butterflies and moths, that the red grubs on his potatoes change to potato beetles and that maggots develop into common flies. He also observes that horseflies attack his stock more abundantly near muskeg and the edges of boggy timber, but he usually fails t realize that those are some of the worst breeding places of the immature stages, or "maggots," of the Tabanidae, and that, as with the mosquitoes and blackflies, it is only the females of the horsefly family that have the blood-sucking habit. Tabanids, other than the tropical species with rapid development, do not appear to lend themselves very readily to complete rearing from the egg in the laboratory. Webb and Wells (1924) experienced considerable difficulty with T. punctifer and T. pheanops, even using a natural substratum and in spite of numbers of egg-masses available. Egg-masses of Minnesota horseflies have been found by the writer on only three occasions. Larvae of two of these were carried through to the adult stage, three T. lasiophthalmus adults emerging. The technic used in rearing these and field-collected larvae of other species has THE TABANIDAE OF MINNESOTA 13 been described elsewhere (Philip, 1928). The latter species has also been reared by Hine (1906). Before presenting the detailed observations on T. lasiophthalmus, a brief summary of its life history, based upon field and laboratory find- ings, will be advantageous. This species appears to prefer breeding places somewhat removed from open water. Eggs are laid in shining black, subconical masses of three tiers, these being fastened on the blades of sedges and coarse grass. June andjuly constitute the probable period of oviposition. The incubation period was not determined, as freshly laid masses were not found. Hatching occurs practically simulta. neously over the whole mass, the first molt taking place as the young larvae leave the egg. Dropping to the ground in a writhing mass, the larvae are probably gregarious for a time, until the yolk becomes reduced and they then scatter, impelled by the urge for food and by cannibalism. The larvae are highly predaceous and feed on almost any soft-bodied organ- ism unfortunate enough to cross their paths. Eight molts are apparently the usual thing before winter sets in. They become dormant in the late fall, refusing food even tho confined in a warm laboratory. The ninth molt occurs in late April or May, revealing the pupa. A little food may be taken in the spring before pupation, but apparently this is not usual, as larvae collected in nature have invariably refused such offerings. The pupal period lasts 13 to 16 days. • Pupa- tion of larvae from the field occurred May 23 to June 2 and emergence, June 6 to 15. The species appears to be single brooded in the vicinity of Minne- apolis. Nothing is known concerning the natural length of life of the adults or their mating habits. The habits of the larvae appear well adapted to the muskeg type of country in the north, where the adult is so abundant as to constitute one of the major pests.

Tabanus lasiophthalmus

Detailed observations.—The egg.—On June 22, 1925, two egg- masses were found on the upper sides of grass blades in an open swale surrounded by scattered trees about a mile west of University Farm. They were situated about 7 inches off the ground and 3 to 4 inches from the tips of • the blades. A small pool of water occurred about 25 feet down the grassy .dip, the turf also being moist below :the sedges bearing the eggs. The masses had the characteristic rounded appearance figured by many authors for various Tabanus spp.—a regularly arranged, downward-sloping basic layer on which were superimposed two smaller layers also sloping in a similar direction (Fig. ). The 14 MINNESOTA TECHNICAL BULLETIN 80 eggs of the uppermost layer were more irregularly arranged to make the whole mass appear rounded. All exposed surfaces, i.e., not in contact with other eggs, were of the usual blackish color. The distance from the standing water among moderately dense grass gave the opinion that the hatching larvae could adapt themselves to a semi-terrestrial habitat altho their markedly swollen tracheal trunks probably indicated the usual preference for oviposition by adults in the proximity of water or very wet soil, an inference supported by the finding of mature larvae of this species in wet sod in the spring.

Egg-Masses of Tabanus Fig. 1. T. lasiophthalmus on Sedge Fig. 2. T. stygius on Sagittaria

One of these batches hatched some time between 10 :30 a.m. and 5:00 p.m., on June 24, two days after collecting; another had hatched before being found. Therefore, altho they were originally within a foot of one another, they were probably laid by different females. The larvae of the first egg-mass were allowed to drop into a small amount of water at the bottom of the vial in which the eggs had been pinned to the cork above. They were then transferred to small stender dishes and labelled Lot No. 2 (see Philip, 1928). On July 1, another almost identical egg-mass was found in the same grassy hollow. The moisture in the pond had practically disappeared, leaving a small area of grass-surrounded black muck. This egg-mass was located in the grass about io feet up the slope from the margin of the grass about the temporary pond and, as before, 3 inches from the tip on the upper surface of one of the grass blades. No adult females were observed in the vicinity, as though standing guard, as reported by McAtee (1911) for Goniops chrysoconta. On July 4, three days after collecting, this batch hatched about 8:oo a.m. The majority emerged almost simultaneously, as observed in numerous Chrysops egg-masses collected. The last few were seen wriggling forth from eggs on the interior of the mass and crawling THE TABANIDAE OF MINNESOTA 15

to a projecting egg at the apex of the mass where they proceeded to molt before falling into the water in the vial. A few larvae were observed to be attempting to molt after dropping off the mass but the majority had shed their skins before leaving the mass. A few strag- glers came out at intervals during the day and one was seen to emerge on the next day. The conformation of the mass prevented a very few from escaping. The larvae of this lot were labelled Lot 3 and treated as those in the preceding batch. The photograph (Fig. ) was taken of egg-mass No. 2 shortly before hatching occurred, June 24. The wrinkled and slightly collapsed appearance of eggs containing larvae is well illustrated. This egg batch was also parasitized by Phanurus entersoni Girault. The larva.—The young larvae of T. lasiophthalinus in each batch were allowed to remain together in stender dishes for a few days until they had begun to develop. Strips of paper toweling were spread over the bottom and up the sides of the dish, just enough water being introduced to cover the bottom of the dish in a shallow, layer to allow the larvae to move about and still reach the surface of the water for respiration. Most of the larvae had filled the trachea with air before dropping from the egg-mass, consequently floated on the water, the tracheal trunks showing a vivid waxy white due to the contained air and to light ref radion. A very few that had not succeeded in molting sank to the bottom and continued a writhing movement in attempting to get rid of the first exuvium. The tracheal trunks in these were of a very dull hue, due apparently to lack of air or to the loosening of the intima preparatory to molting. The latter larvae soon died. At time of hatching, three larvae measured 1.71 to 1.91 mm. when stretched out. One newly hatched larva of Lot 3 was 2.15 by 0.37 mm. across the pseudopods of the first abdominal segment. Yolk was very prominent in all the larvae as a pale, greenish mass within the abdominal segments. The two black bodies in Graber's organ and the eye spots in the head also were conspicuous. There was no terminal stigmatal spine present during any of the larval instars. By io :oo p.m. on the day of hatching, several of the larvae were found to measure 2.6 to 2.8 mm. At this time they had congregated under the filter paper in closely packed groups with the siphons piercing the surface film. If disturbed, the siphons were quickly withdrawn but the larvae remained closely packed together. The chief response seemed to be thigmotactic, a strong desire to be under something. There was no indication that even the strong light under magnification bothered them until they felt a change in temperature. They were not interested in nutriment in the form of bits of earthworm or crushed snail at this time nor were there any signs of cannibalism for two to three days after emergence. i6 MINNESOTA TECHNICAL BULLETIN 80

Altho food was continuously available, no evidence of acceptance was observed until the second day after hatching among the larvae of either of the lots. Food, as soon as taken, could be seen as a darker mass anterior to the diminishing yolk in the larvae that accepted meals on bits of maggots, annelids, or snails. A few larvae (Lot No. 2) were isolated in groups of five in small stender dishes (4oxo mm.) until approach of the second molt. These were observed to attack chopped fly maggots several times during a day, but up to the fifth day, as with those in the original dishes, they were quickly satisfied. In one dish containing a small strip of paper and a little sand, five unfed larvae were resting under the paper strip on the bottom of the dish. A freshly cut section of. maggot was dropped on top of the sand. Within 3 minutes all larvae had found the food, altho they had remained concealed beneath the wet filter paper up to that time. In another dish, the larvae converged from different directions on a piece of macerated but quiver- ing snail at the top of the sand. By the second day the largest were 3.0 to 3.7 mm:in length. An isolated group of twenty-five larvae of Lot No. 2 were kept without access to food for 3 days. The amount of yolk had become very much reduced, but the larvae were quiet. A portion of killed fly maggot was then placed on the paper strip several mm. away from the resting larvae. They immediately became restless, prodding about with their heads and working the mandibles, and eventually they began crawling in search of the food, of which they had seemed to become suddenly aware. During the short search, they repeatedly came in contact with one another but still evinced no interest in attacking fellow larvae, despite their obvious hunger and the stimulating presence of food. From this time on, considerable variations in the rate of growth were noticeable among individuals of both the stock lots and isolated series of larvae, but this was not so marked as in the slower developing, younger instars of T. stygius discussed later. Detailed observations were kept on the isolated larvae. These variations are apparent in the records of certain of the isolated larvae, as presented in Table I. It will be noticed that nine larval instars were discovered in this species, the first lasting only between hatching and the first molt. Mitz- main (1913) reports three molts in T. striatus; Webb and Wells (1924) remark that there is little doubt of an intermediate molt between the second and last. The methods of rearing had prevented previous investigators from determining the exact number of larval stages. The valuable contributions of Isaacs (1924-1925) giving the first complete reports in this regard had just come to hand as the above observations on T. lasiophthalmus were completed. The writer had also reared Table Variations in Rate of Larval Growth of Tabanus lasiophthalinus-Hatching Occurred June 24 (Lot No. 2) and July 4 (Lot No. 3), 1925

Data on date of molt and comparative measurements at different times

No. of Laboratory bench near window Dark room Laboratory bench 25° C. molt 2-a 2-b • 2-C 2-d 2-e 2-X 2-y 2-Z 3-a 3-b 3-c 3-d

June 24 June 24 June 24 June 24 June 24 June 24 June 24 June 24 July 4 July 4 July 4 July 4 2 July 5 July 9 July 4 July 7 July 6 July 8 July 6 July ii July 14 July 12 July 13 July 12 3 July 14 July ig July II July 15 July 14 ? ? ? July 24 July 22 July 24 July 21 4 July 24 Aug. 2 July 22 July 29 July 26 ? - ? ? Aug. 5 Aug. 1 Aug. 4 July 30 5 Aug. 3 Aug. 18 Aug. 1 Aug. 7 Aug. 4 Aug. 17 Aug. 6 Aug. 9 .A.ig. 19 Aug. io Aug. 15 Aug. 7 6 Aug. 12 -/- Aug. 14 Aug. 19 Aug. 12 Aug. 25 Aug. 16 Aug. 18 Aug. 27 Aug. Is; Aug. 24 Aug. 16 7 . Aug. 20 -1---- Aug. 23 Aug. 18 Sept. 8 Aug. 29 Sept. 6 Sept. 6 Aug. 27 Sept. 4 Aug. 25 8 Sept. 16 Sept. 17 Sept. 6 Sept. 22 Sept. 19 Sept. 18 Sept. 29 Sept. 17 Sept. 28 Sept. 14

Died . Aug. 26 Aug. 21 Mar. 8 Apr. 25 Mar. 10 ' Feb 20 May 15. Mar. 3 Feb. 6 1926 1926 1926 1926 Pupa May 17 May 12 May 5 1926 1926 1926 Adult May • 31 May 26 May 21 Measurement in mm. (body length X diameter head across base of mandibles)

{ July II 1925 3.6 3.9 5.4 4.0 3.7 • 4.0 3.4 3.9 2.5 3.1 3.3 3.5} July 5 xe.49 xo.59 xo.82 • xo.56 xo.53 x.0.49 xo.50 x0.51 xo.5 xo.9 xo.7 xo.7 Aug. 25 Aug. 17 14.2 17.8 7.5 9.9 15.8 9.5 . 6.3 6.6 , 12.6 14.1 15.8 19.5} X2.I X1.2 X I.7 X2.6 X2.2 X1.7 xo.86 x0.9 _ x2.3 x2.3 X2.2 X3.3 { Oct. 4 Oct. 4 24.2 • . • • • • 28.5 26.3 24.2 25.3 24.9 26.3 26.8 26.5 26.9 1 X4.1 • • • • • • • x4.7 x4.2 x4.2 x3.9 x4.6 x4.2 x4.8 x4.2 4.7 1 Jan. 28 1926 23.9 • • • • • • • • 26.5 25.9 21.9 20.8 23.6 24.0 23.9 23.7 23.0 1 Jan. 28 x5.1 • • • • • . • • x5.2 x4.9 x5.o x5.2 x4.9 3c4.9 x5.o x4.7 x5.0 18 MINNESOTA TECHNICAL BULLETIN 80 larvae of T. stygius through the fifth and sixth instars during the previous summer (1924), when they were accidentally killed in a half- ()Town condition. It is interesting to note in this connection that in the spring of 1925 (unpublished thesis), before a complete rearing had been made, the writer said, "With five molts up to 10 mm. in length in reared larvae (T. stygius), and a general molt observed in larvae collected in the field at around 15 mm., 21 min., 26 mm., and the final one disclosing the pupa, the total number would appear to be around 9 for this region." It was hoped that measurements of the head capsule would provide a rough key to the age of the larva, but it was soon found that a larva of a younger instar might be at least as large as a more speedy fellow larva that was in the next instar. A check on the number of molts, during the early stages at least, can usually be obtained by counting the pairs of black bodies in Graber's organ. Graber's organ.—Very little is known regarding the significance or function of this organ. It is located dorso-anteriorly in the anal segment just behind the posterior end of the heart. It is piriform and connected by a slender stalk to a pore opening in the integumental fold between the last segment and the siphon. Muscle and nerve attachments anteriorly, ventrally, and caudally, in addition to certain mem- branous tissues as described by several authors, maintain its suspended position. The organ is readily located because of the contrasting black, pedunculate bodies within it. Studies by several investigators have been summarized by Marchand (1920). Detailed notes were kept on changes observed in this organ in the various instars of T.lasiophthalmus (Fig. 5, Plate I). Paoli's (1907) explanation of the hypodermal origin of the organ and the suggestion that the bodies would be replaced in the anterior or functioning chamber at every molt, were verified during these studies. One pair only is formed for each exuvium shed. The anterior pair alone are fixed and functioning. Those situated posteriorly are usually not contained within separate septae, as described for certain species of larvae, but are seen to shift their positions during movement or after a considerable elapse of time (compare the 2 diagrams, September and January, for the eighth instar in T3-a or in T3-b, Fig. 5). In the younger instars most of the pairs of bodies are retained, but in older larvae many of the replaced bodies are scattered along the terminal tube or discharged during the molting process. In T. lasiophthalmus even the loose bodies along the terminal tube were never seen to be discharged before the next molt. A pair of bodies was observed to remain near the end of the tube in the eighth* instar in T2-a and to be replaced at the succeeding molt by another THE TABANIDAE OF MINNESOTA 19 pair, as shown in Figure 5. Not infrequently a pair becomes separated, one body only being discharged or situated in the terminal tube and the remaining one in the non-functioning chamber. Less frequently a pair is observed to have split, one remaining in the anterior capsule with-the functioning pair of bodies, T 3-b seventh instar, and in one instance, T 3-a eighth instar, 5 bodies were seen in this situation. Whether or not a body moved forward and the old pair was not dis- carded at the molt is uncertain in the latter case. The indications of an approaching molt are shown in the second figure for the eighth instar, T2-a, about 3 hours before shedding the skin, and in T3-b, fifth instar, on the day previous to molt. Judging by the figure of Graber's organ in the larva studied by Henneguy, this larva was also almost ready to molt. It should be emphasized that Figure 5 is strictly diagrammatic and intended only to portray changes in the organ relative to positions and numbers of black bodies within it. In comparison to T. lasiophthalmus, Chrysops larvae less frequently dis- charge these bodies at the molt and the septae in the posterior Chamber are usually apparent. The molting process.—The opportunities for studying molts in the larvae are ideal with the younger instars because of the transparency of the integument, and the smaller scale of the parts for study with the compound microscope. An approaching molt is rather easily pre- dicted by the distinctness of a new capsule in Graber's organ containing the not yet pigmented bodies in front of the anterior functioning capsule, by the refusal of food about 15/2 to 3 days previous to molt, and by the loosening of the outer epidermis, which is especially plain at the thoracic incisures. At such times the tracheal trunks frequently show a slight collapsing or folding. The first changes preceding the actual casting of the exuvium are noticed in the displacement of the eye spots and in the later withdrawal of the head from the old capsule; the new light brown Mandibles can plainly be seen withdrawn from the old, darker ones but still within the old head capsule. A new posterior tracheal junction is to be seen partially withdrawn from and between the old, heavily chitinized one. The larva may exist in this condition overnight, at least remaining quiet for some period before the final exertion which rids it of the old exuvium. A sudden retraction of the head frees it entirely from the old head capsule, which is pushed forward and drops ventrally as the dorsum is split between the first and second segments of the thorax. From this time until the last remnants of the trachea are cast loose, the larva does not, apparently, take air. After dorsally splitting the skin, the larva stretches out, becoming long and very slender, seemingly for the 20 11/IINNESOT4 TECHNICAL BULLETIN 80 purpose of loosening the epidermis of the locomotory pads and the tracheal intima. By a series of peristaltic waves from the posterior end forward, it begins to work out of the exuvium, withdrawing the siphon and spiracle entirely from the old one. By retractions of the new siphon, the linings of the main tracheal trunks and their branches are gradually pulled out. At the same time two opaque whitish lines along the sides of the abdomen indicate the casting loose of other linings through the thoracic- and lateral abdominal spiracles. By this time the exuvium is fairly well off, and gathered at the posterior end of the body. The efforts thus far have not changed the position of the larva much, but at this point, the larva resumes, for the first time during the process of shedding the old epidermis, its characteristic, locomotory movements. As it crawls away from the exuvium, the finer branches of the thoracic tracheae, pulling loose through the thoracic spiracles, trail out in the water behind the larva. The larvae seem not to take air immediately after molting, altho they go for some time without a fresh supply during the process. Mitz- main (1913) observed the use of an excrementous cement to fasten the end of the abdomen to the glass and sand during molting of T. striatus. Molting as observed above, however, was accomplished with no apparent difficulty in shallow water over a smooth glass bottom affording practically no traction to the larvae of T. lasiophthalinits. The manner of feeding among these predaceous larvae is also of interest. They indicate an awareness of the presence of food by a rotating and exploring motion of the head and an alternating movement of the powerful mandibles. Upon contact with the prey, the head of the tabanid is thrust forward, and, at the same tinie, both mandibles are plunged forward and down. Having secured a hold on the prey, one mandible retains its position while the other is used to force entrance for the pointed head, after which the mandibles are Usually observed to alternate during the evisceration of the victim. A group of spines on each side above the antennae, usually lying appressed to the head, is seen to become erect as the respective mandible is driven down they appear to functioii in holding and rending the tissues of the prey. The underside of the supplemental piece. of the mandibles is also seen to be setose. A small bolus of food may be seen to pass at intervals down the oesophagus as the larva feeds. One almost mature larva observed, attacked a piece of earthworm and fed almost continuously for 6 hours another fed, with one 15-minute rest, for 5 2 hours. A constant rotating and prodding with the head is maintained during the active feeding. Feed- ing is best watched under the binocular microscope. Food was offered continuously, usually in the form of killed fly maggots up to the end of October. All larvae but 3, which were stored THE TABANIDAE OF MINNESOTA 21

in a photographic dark room (Table 1), refused food after the first week in October. Earthworms obtained in a greenhouse were offered at varying periods through the winter, but only once (in February) was a small amount accepted by one larva before the middle of April. The larvae had been transferred to vials in November and handled the same as mature larvae taken in the field. All but 3 of the larvae carried through the winter died before pupation, owing to accidents and a peculiar malady in which the excretory functions apparently were involved, as evidenced by marked atrophy of the Malpighian tubules, frequent plugging of the anus, and by a general bloated appearance. Live maggots offered as food frequently retaliate and result either in injury to the tabanid larva attacking it, or in simply driving the latter away temporarily. In the latter case it was repeatedly observed that if one of the mandibles of the tabanid had pierced the skin of the victim, the latter fought desperately for a moment, then gave a few spasmodic jerks and almost at once appeared to have become paralyzed as though overcome by a toxin. This was also noticed after a somewhat longer interval in victimized earthworms as noted previously (Philip, 1925, unpublished thesis). Investigations revealed pores in the mandibles of the larvae near the tip in front. This was also noticed by Isaacs (1925), who has shown by careful sectioning that the larvae ingest their food as liquid through these pores, the mouth being atro- phied. The arrangement of the pores is somewhat remindful of those seen at the tips of the chelicerae of certain arachnids except for the difference in positions and slightly smaller relative size of the latter. Larva 23 to 26 mm. in length. Color, a light translucent amber in living larvae but dirty in preserved specimens. The pseudopods are reduced, joined across the dorsum as pubescent stripes no pigmentation at incisures or on anal segment. A series of oblique dashes occurs dorso-laterally, a pair near the anterior margin of each segment except the anal. Body striae are rather coarse, a little finer laterally and on the siphon. Dorsal and ventral areas on thorax smooth, shining, a few striae posteriorly on each segment. Smooth spot in the middle of the prothorax, cephalad. Spiracles in median line on all segments except prothoracic and anal discernible as small circles of "spongy" tissue at lower hind margin of each median pad, a little lower caudally. In larvae taken in nature, the pubescent areas around the abdominal segments become dirty, giving them a faint pigmented appearance in many forms (Fig. 6, Plate II). Anal segment (Fig. 7), without lateral or ventral markings, the siphon short, finely striate. The approach of pupation is first indicated by refusal of the larva to feed. Among the 3 reared specimens, No. T2-a did not accept food to the writer's knowledge between the time of dormancy the preceding fall and pupation May 17 of the following spring; the other 2 larvae accepted food in the spring up until 8 and 14 days before pupation. The transition is accomplished by retraction and immobility of the head and the appearance of the peg-like mesothoracic spiracles , 22 MINNESOTA TECHNICAL BULLETIN 80

at the incisures between the first 2 segments, in the median line. A shrinkage takes place, the skin loosens and finally the abdominal spines of the developing pupa can be seen. Up to this time the head capsule of the larva lies imbedded between the antennae and immediately below the frontal carinae of the pupa. This is pushed out and some time later the skin is split dorsally just posterior of the pubescent collar on the front of the prothorax, the pupa wriggling out of the rent which occurs along the whole dorsum of the thorax. This prepupal stage lasts two to three days, depending on the temperature. Special comment.—Before leaving the detailed discussion of the development of the larvae, two moot questions are of interest for discussion :( ) The number and- structure of antennal segments has been considered of importance in connection with the generic differentiation of the larvae since the appearance of Hart's admirable paper (1896). Marchand's statement summarizes the accepted views up to 1920, "The larvae are eucephalous, with head well developed but small, bearing the three-jointed antennae—the basal joint being short, the others of varying length." Isaacs (1925) states that the antennae of Tabanus are not more than two-jointed and quotes Mallock (1917) as regarding larvae of Chrysops and Tabanus as with two antennal joints. The latter makes no definite statement as to number, however, speaking only in comparative terms of "basal and apical" or "basal and preceding segment," but does refer to larvae of Goniops as "3-jointed" following McAtee (I9I ). Curiously enough, the latter author, in giving detailed figures of the head and appendages of a newly hatched and of a mature larva, figures the former as having two joints, the apical being bifid; and the_mature larva as with three joints, the basal being elongate and the apical being very small and pointed. Detailed studies by Boving (Webb and Wells, 1924) have clearly shown three joints in the larval antennae of T. punctifer; the flattened, chitinous, backward extending, basal joint was overlooked by Isaacs. (Inciden- tally, the latter author wrongly identified the proximal part of the mandibles, considering them to be the maxillae). This fixed basal segment can be seen plainly in T. stygius, with the second joint freely articu- lating upon it. Brauer's (1883) description of Hexatonta pellucens larva seems to have been the first notice of a bifid apical arrangement in tabanid antennae; Isaacs also figures such a condition in the Indian species with which he dealt. The bifid condition of the apical joint has been noted in larvae of both Chrysops and Tabanus in Minnesota; the two branches may be equal or unequal in length from the tip of the preceding segment. In some instances, one branch is practically indis- cernible. Careful examination from several angles is necessary to THE TAB,4NIDAE OF MINNESOTA reveal the characters of the apical joint. Taxonomic use of these characters is therefore unsatisfactory but the relative lengths of the second and apical joints are of generic significance. 2. The usually accepted view regarding the respiratory apparatus in tabanid larvae is, as expressed by Patton and Evans (1929), metapneustic. They have occasionally been referred to in an amphipneustic sense alluding to the mesothoracic spiracles, which are minute and situated laterally in the anterior incisure. These have been particularly noticed because of their evagination as small spiracular "pegs" or projections during the prepupal or quiescent stage before pupation. Close observation during the act of molting, however, reveals that tracheal filiments are cast loose laterally on every segment except the prothoracic and the anal. This is particularly noticeable at the beginning of the process, as mentioned elsewhere. The writer then under- took to dissect larvae of T. lasiophthalnzus and T. stygius and to determine the tracheal connections along the sides. The non-chitinized spiracular openings were easily found by following out the rather small tracheal attachments. The spiracles occur in the midline at the posterior incisures of the second and third thoracic segments and just at the edge of the posterior margins of the large lateral pseudopods dropping below those margins in the last two or three segments. That they are open and capable of functioning is attested during the molting process. As to actual use, the active larva is probably essentially metapneustic, especially the aquatic forms, as suggested by the sole reliance on the siphon during aerial respiration while partially submerged. Stammer (1924) suggests skin respiration to account for resistance to long submersion. A gaseous interchange at the lateral spiracles is possible, but does not seem a probable alternative, owing to the small size of connecting tracheae. The Minnesota species of Tabanus tested, however, were susceptible to comparatively rapid drowning; Chrysops were much more resistant in that respect. The subject of respiration in tabanid larvae is- an open and promising,field for intensive study. The pupa. (Plate II, Fig. io).---This stage in T. lasiophthalmus is typical of thgt described and figured by many authors for species of Tabanus. The terminal segment with its projections, termed the pupal aster by Neave (1915), has been much used in differential diagnoses (Plate II, Figs. 8 and 9). The number and arrangement of the hairs and their basic tubercles over the cephalo-thoracic region and first abdominal segment are constant for the various species. This stage lasted 14 and 16 days in 3 reared specimens (Table ). In others collected as larvae in the field, the period varied from 13 to 16 days. The sexes are apparent in this stage because of reduction of the anal fringe in the female to two ventro-lateral combs on the terminal segment. 24 MINNESOTA TECHNICAL BULLETIN 80

Pupa 16.5 mm. Frontal carinae prominent, contiguous in the middle and strongly rugose between, above. Frontal tubercles very prominent with single bristles. Thoracic spiracles gently bowed, narrowly but strongly hooked cephalad. Circlets of spines entire on all abdominal segments, stout, longest on caudal segments ; composed of a double row, spines of the anterior row being short, the posterior very long and heavy. Remarkable dorsally in the even and rather sparce spacing giving an appearance of alternation of the long and short spines. Long spines found across the dorsum of second as well as on the following segments. Anal segment with median terminal teeth very long and rather slender. Spines stout and long usually, those of the dorso-lateral and lateral combs variable in number, frequently 2 in the former, never over 6. Male with io to 14 spines in the anal fringe not including the lateral comb. Just preceding emergence of the adult, the eye color, body hairs, and even the abdominal pattern are visible through the pupal integument. The loosening of the trachea about the spiracular openings is also apparent. Splitting occurs along the dorsum of the thorax and around the upper and lateral margins of the head to allow the escape of the adult. Because of their obtectate pupae (i.e., naked pupae with closely apposed appendages after shedding of last larval skin) and the manner of emergence of the adults, the Tabanidae are classed with the orthorrhaphous Diptera. Knabb (191 i) has summarized the information regarding the eclosion' of the imago in several families and emphasizes the application of pressure to effect emergence by means of imprisoned air, particularly in the Cyclorrhapha. He quotes observations by Eysell, in 1905, who described the emergence of mosquitoes as a splitting of the pupal shell and elongation of the body by the ingestion of air while the "hid end of the body still remains exactly in the same position as during the pupal stage." The writer has observed the process closely in certain African mosquitoes as well as with Minnesota horseflies. In both instances there was a preliminary series of movements on the part of the terminal segments of the abdomen as seen through the pupal skin, before any apparent attempt was made to split the pupal shell. Particularly in T. lasiophthalmus and in Chrysops mitis, the abdomen was actually observed to be "crawling" forward so that the tip was well into the seventh segment before a sudden surge accomplished actual fision on the thorax and head. The tracheal, linings could be plainly seen trailing out of the spiraeles as the abdomen was drawn forward in a series of peristaltic contractions. The adult remains in a teneral condition and in a quiescent position from about a half to three-quarters of an hour, altho specimens in nature will fly considerably sooner than that if disturbed. During this period several drops of meconium are observed to be voided. Collection of adults of many species in this condition has been reported in the THE TABANIDAE OF MINNESOTA 25 literature and several species of Tabanus as well as two of Chrysops have been found clinging to blades of grass in a freshly emerged condition in Minnesota. The pupa in nature forces its way to the surface of the sod with the aid of the spinose fringes and projections on the abdomen. Early Stages of Other Species On the basis of data accumulated.thus far it appears that a few of the larger or later appearing Minnesota horseflies may occasionally re- quire two years to complete the life cycle, but the usual life history probably occupies but one year, the various species going through the winter in the larval stage. Mitzmain (1913) has reported the minimum requirements for T. striatus to be 52 days, while King (191 ) reports 48 to 131 days as the metamorphic requirements of certain species in the Sudan. Isaacs (1924) reports complete development in periods as short as 57 days for Indian species, three broods a year being usual for most species of horseflies in India. Hine (loc. cit.) was the first to carry a horsefly species through to adult from egg, using jelly glasses filled with dirt which precluded close observation of larval molts and other activities. Other investigators, among them Hart (1895), Marchand (1917), Webb and Wells (loc. cit.), Cameron (1926) and Stone (1930) have contributed to the biologies of various North American species of Tabanidae.3 None of them have, however, obtained accurate information on the number of larval instars, the molting process, arid other observations. Most of the species were reared from fairly mature larvae or pupae collected in the field, as is the case in this investigation. All biological information for world species was admirably summarized by Marchand (1920) up to that date. One is impressed in perusal of the literature by the almost universal semi-aquatic habitats in which tabanids have been taken in the immature stages. However, the statement by Osborn (1913) that "all Tabanidae undergo the larval stage in water and so belong to the hydrophytic fauna, no matter how far afield the adults may roam in search of food" is somewhat erroneous. A few species of terrestrial tabanid larvae have been reported (Hart, 1894 and Brimley, 1909) in addition to the often-described larva of the European Hacmatopota pluvialis. Marchand (1920) lists 18 species as being probably terrestrial. The writer has taken larvae and pupae of T. lasiophthalnuts near Fort Snelling, in rotted logs far from any open water, and with little

3 Papers by Schwardt have come to hand since this paper was sent to press, "Notes on the Immature Stages of Arkansas Tabanidae" (Jour. Kans. Ent. Soc. 4:1-15, 1931) which discusses 7 species of Chrysops and 8 of Tabanus. Two of each of these were also reared in this study. Also, "The Biology of Tabanus lineola Fabr." (Ann. Ent. Soc. Amer. 24:409-416) reporting 2 generations per year, mass rearing from the egg, and 3 to 7 larval stages among other observations. 26 MINNESOTA TECHNICAL BULLETIN 80 excess seepage in the humus and leaves on the ground below. Two pupae of this species were sent in from Hopkins, near Minneapolis, taken in a strawberry patch June 20 and 30, 1916. One produced a female T. lasiophthaimus. One larva of Tabanus sp. without swollen tracheal trunks was taken outside Minneapolis among the fallen and decayed leaves on the forest floor of a basswood-maple climax forest. There was no open water or marshy ground in the vicinity. This larva died before pupation, unfortunately. Twenty square-yard samples at various places in this environment yielded only the one specimen after thoro search, altho numbers of grubs of Phyllophaga abounded. Furthermore, the egg masses of T. lasiophthalmus reported in the previous section were found on sedges of a swale 15 to 25 feet from a small pond the water of which had practically disappeared, and before the summer was over, the ground had baked dry. Larvae of this species have swollen tracheal trunks and are adapted for an aquatic existence, but can, and undoubtedly do, live a considerable time without any free surface moisture. It seem' s probable that many more species frequently pass part or the whole of their larval existence under moist terrestrial conditions but they are so scattered as compared to the species concentrated at the water's edge that the terrestrial species are only infrequently found by collectors. It is noticeable that the greatest concentrations of even the "hydrophytic" species are found in the spring just before pupation along the margins of streams and ponds. In the late summer and fall not nearly so many are found at these margins, a fact which is in part, perhaps, due to the greater numbers of younger instars, and in part to a wider distribution above or below the water margin. The latter suggestion is supported by Stammer's (1924) observations on under-water species and their toleration of prolonged submergence ("weeks") which he explains on a basis of skin respiration. That many larvae, Chrysops particularly, live normally on the bottoms of ponds in this country is attested by the situation of the egg masses some little distance from shore. Two nearly mature larvae were reported by the writer (1928) in bottom samples taken in a pond along the outer margin or open water of the cat-tails in late fall. It was suggested that the stigmatal spine could be employed to tap the air spaces in the roots of aquatic vegetation. Newly hatched Chrysops larvae of several species have never been noticed by the writer to break the surface film with the .stigmal spine for air as the mature larvae of both Chrysops and Tabanus do. T. stygius and T. lineola are the only local species of the latter genus with a protrusile stigmatal spine comparable to that in most of the Chrysops larvae. Several workers, including the writer, have always found that larvae of various Tabanus species were easily drowned by submergence. THE TABANIDAE OF MINNESOTA 27

Stammer reports some larvae that become active after 2 to 4 weeks of submergence, which indicates a remarkable adaptation on the part of some species. One of the Chrysops larvae taken in a bottom sample, as previously reported, was recovered by the writer from among many other dead specimens of aquatic insects and crustaceans at the bottom of a vial filled with formalin of analyzed strength of 0.825% after remaining for 5 days in that situation. This shows something of the resistance displayed by these *larvae. This particular larva remained active for several weeks, then an accident resulted in its death. The methods of collecting and rearing used in these studies have been reported by the writer (1928) and will not be mentioned here further than to call attention to the use of a homeopathic vial method of rearing that facilitated observation on the later larval and pupal stages by eliminating the use of dirt as the substratum. During two summers of field collecting, adults have been reared from larvae of 10 of the 16 species of Chrysops occurring in Minnesota and of 9 of the 28 species of Tabanus taken within the state. Another larva of unknown species of Tabanus was also found. Most of these larvae were mature when collected and stress of other duties prevented detailed studie before pupation occurred in the case of C. striatus, C. wiedemanni, and T. epistates. Keys to the known larvae and pupae have been presented in Part II. Tabanid associations for species covered in this paper may be classed according to the larval habits and type of environment in which they have been found, someivhat as follows (authority given in parenthesis for species not found in a given situation in larval or teneral adult condition by the writer). Semi-aquatic and aquatic larvae A Lenitic associations—standing water a Temporary pond frequenters Chrysops----aestu,ans, callidus, excitans, sackeni, indus, striatus, mitis, celer (Stone), vittatus (Stone) Tabanus—stygius, lineola, nivosus, reinzerardtii, illotus, epistates, trimaculatus, atratus (authors)', bicolor (Stone) b Permanent pond frequenters a' Marshes—Indefinite shore line Chrvsops—sackeni, aestuans, callidus, fulvaster, niger (Stone) Tabanus—stygius, illotus, reinwardtii b' Lakes—Well marked shore line Chrysops—excitans, montanus, mitis, earbonaritts, frigidus (Cameron), moechus (Stone) Tabanus—reinwardtii, epistates, lineola, .stygius, nivosus MINNESOTA TECHNICAL BULLETIN 80

B Lotic associations—running water Chrysops—indus, zviedemanni, callidus, fulvastcr, carbonarius (Stone) celcr (Stone), niger (Stone), vittatus (Stone) Tabanus—atratus, trimaculatus, reinwardtiii, bicolor (Stone) C Bogs, etc.—no open water in probable range of larvae Tabanus—lasiophthalmus, trispilus, trcpidus (Stone) 2 Terrestrial larvae A Shaded associations—forests, etc. Tabanus—lasiophthalmus, undetermined species B Open associations—meadows, fields, etc. Tabanus,—costalis (Hart), /asiophthahnits The foregoing table is presented merely for convenience in visual- izing larval habitats. The overlapping of species and a general consideration of the larval habits indicates that the line can not be drawn too finely, since the larvae themselves utilize different "strata" of the same environment at different seasons of the year. Sedges or emergent aquatic vegetation in the bend of a creek may offer just as attractive features to the ovipositing female of a particular species as the margins of a weedy pond. It must also be recalled that differential collecting and concentration of the larvae of certain species along the water's edge may have considerable to do with the comparative abundance, of species recorded under the lenitic associations. In addition to the following specific larval notes, supplemental characters have been presented in the keys to the immature stages at the end of Part II. Measurements are of necessity rather arbitrary, but an attempt at uniformity was made to obtain readings when larvae were stretched out preparatory to crawling. Measurements of the head capsule of the larvae were taken from the last larval skin. Altho the posterior ends of the mandibles and pharynx project beyond the epicranium posteriorly, it was decided the safest Comparative measurement would be from the tip of the labr.um to the hindermost chitinized margin of the cranium itself. Diameter in Tabanus is given across the head at the base of the labrum and piercing spines; in Chrysops, because of the extreme tapering and small head anteriorly, the measurement was made across the widest part of the epicranium behind.

Tabanus stygius ,Larvae of this conspicuous, large horsefly were commonly found in muck at the water's edge of most sloughs and ponds in the vicinity of St. Paul and Minneapolis. They may be inhabitants of both temporary and permanent pond margins. They were taken only once in a rotted log lying partially submerged and one pupa was found among grass roots about a foot above the water's edge in a -steep embankment, in THE TABANIDAE OF MINNESOTA 29 late June. The mature larvae were found most abundantly in May. Some accepted food in the form of snails, bits of earthworm, and fly maggots, and others refused to eat. The larvae are yellowish, infrequently pale, strikingly ornamented with dark pigment on thorax, incisures and anal segment. Their appearance is much like larvae of T. atratus, but not so heavily marked, lacking the enlarged thoracic stripes. In this they resemble those of T. punctifer described by Webb and Wells (1924). They measured 36 to 45 mm. when stretched out. The tracheal trunks are swollen and a sharp, protrusile stigmatal spine is a notable feature of the siphon. Despite the abundance of the larvae, only one egg-mass was located (Fig. 2). It was found August 3, 1924, on the upper side of an isolated Saggitaria leaf over open water about 6 inches deep at Moore's Lake, Anoka County. Dense Typha growths surrounded this patch of open water. About 50 larvae were unable to pierce the chorion of the eggs, but 485 hatched August 5. The former were practically all in the outer or exposed eggs on the mass. The illustration shows plainly the collapsed appearance of the various eggs just previous to hatching. The young larvae contained considerable quantities of greenish yolk: material and the first molt occurred between 2 and 4 hours after dropping into, shallow water provided, in which they had quickly sunk to the bottom. This is in contrast to the molting of T. lasioplithalmus but in keeping with observations on other species reported in the literature. Gregariousness was shown for a time, and unlike young Chrysops larvae they frequently protruded the tracheal spine through the surface film to obtain air. The size averaged between 3.5 and 4.2 mm. Development was much slower than noticed in the rearings of the previous species. Individual differences were therefore much more marked in T. stygius, as shown by a comparison of Tables i and 2. It is also noticed that one molt occurred as late as November 4. Dur- ing October heavy mortality occurred through disease and difficulties in developing a technic, so that by December 4, the last larva succumbed in the fifth instar. All accepted food greedily until just preceding death. In this respect they differed from /asiophthabitus, the larvae of which practically discontinued to feed after the first week in October under the same conditions of storage. Hine (1906) also carried stygius through to about this stage, as judged by size (io mm.), but in the spring "for some reason (they) died without further increase in size." Changes in Graber's organ were again correlated with the molts. Differences in size of the pairs of pedunculate bodies were more marked than in T. lasiophthalmus. Those of the second instar were easily distinguished in the capsule beside the larger bodies of the older stages. Three bodies were noted in the anterior chamber of one larva in the 30 MINNESOTA TECHNICAL BULLETIN 80 fifth instar ; the odd body was obviously "left behind" during the fourth molt, as an extra body was also found among those in the posterior chamber. Table 2 Early Larval Development of T. stygius Under Laboratory Conditions, 1924

No. Aug. 24 Sept. i Oct. 4 Nov. 4 2nd M. 3rd M. 4th M. sth M.

Ti-a .4.36 X 5.48 x 7.24 x 9.64 x Aug. 8 Aug. 31 Sept. 23 Nov. 4 0.52 mm. 0.76 MM. 1.02 MM. 1.21 MM.

Ti-b 4.20 x 5.34 x 8.46 x 9.30 x Aug. 9 Aug. 31 Sept. 18 Oct. 28 0.52 mm. 0.72 mm. 1.22 MM. I.0 MM.

Ti-d 4.0 X 6.93 X 10.39 X 12.87 x Aug. Io Sept. 2 Sept. II Sept. 27 0.52 mm. I.00 mm. 1.32 mm. 1.68 mm.

TI-e 4.44 X 5.00 x 6.44 x 10.23 x Aug. Jo Sept. i Sept. 28 -1- 0.52 mm. 0.39 mm. 0.92 mm. 1.02 MM.

In spite of the relatively slow development of this species in the younger instars, it appears likely that stygius is also only single-brooded. A few larvae of late egg masses may go through a second hibernation as mature larvae, the probable explanation for the last instar larva collected by Hine (1906) in August, which continued eating and did not emerge until the following spring. Mature larvae were found most abundantly in May, usually reaching a maximum abundance in collections after the bulk of the trimaculatus and other species had already passed from the same situations. Larvae that have two or three instars to complete in, the spring would still have time to do so and emerge during the period of normal adult appearance, which is fairly scattered through the summer season. Collections at a shallow, reedy temporary pond in St. Paul revealed numerous samples of mature larvae of this species May i and 3 just above the water margin. Collections May ii at the same pond revealed few larvae along the water's edge but numbers up the bank in the damp earth among grass roots and vegetation. This apparent migration of mature larvae has been noted in other species. On the other hand, little success has attended attempts to collect pupae in these higher situations. The immature stages of this species have been figured by both Hart (1896) and Hine (1906). Only certain significant details of the pupa need be added here. Pupa 26 to 32 mm. in length. Frontal carinae strongly developed, contiguous. mesally in both sexes, the carinal ridge distinctly interrupted by lateral sulci much as in certain species of Chrysops. Tip of antennae short of adjacent line of dehiscence. Double rows of spinose fringes on abdomen rather fine, slender. Teeth of aster not prominent (Fig. 19) ; dorso-lateral comb usually with more than 9 spines. Tabanus trintaculatus Larvae of this species were the most numerous tabanid species taken in the immature stages. All were found about standing water in Hen- THE TABANIDAE OF MINNESOTA 31 nepin or Ramsey -Counties. A few larvae and one teneral adult were also taken along Rice Creek, Anoka County. Such places were usually with permanent water or at least damp throughout the summer. The greatest abundance was in April and early May, but some were taken as late as July. Many accepted food before pupation. Pupation was noted from May 2 to June 27. The earliest emergence occurred May 8 and the latest, June 25. Larvae collected in July were usually in younger instars and carried on for hibernation in the winter. The pupal period varied from 12 to 17 days. The species appears to be single-brooded with possibilities for a few late starters taking two years for completion of their development. Larvae moderately heavily ornate on all segments, whitish, and 30 to 37 mm. when mature. Head capsule of last exuvium, 4.2 by 0.72 mm. Rather easily confused with larvae of reinwardtii but the metathoracic stripes are longer in this species and in those specimens examined, there is no isolated dorso-lateral spot anterior to and above the row of merged spots sloping cephalad on the sides of the anal segment. The siphon, when extended, is also somewhat longer than in reinwardtii. Pupa length, 19 to 25 mm., usually yellowish brown. It is the usual type, the distinctive feature being the rather low, widely separated frontal carinae, especially reduced laterally in the female, and the relatively short stout fringes of spines on the dorsum of the abdominal segments. The pupal aster is shown in Figure 13. Dorso-lateral combs usually with 6 to 9 spines.

Tabanus nivosus Larvae of this frequenter of temporary and permanent pond margins were abundant in collections. They have been .taken,from April to June in Hennepin and Ramsey COunties and 3 were also found along a lake shore near Vining, Ottertail County, in June. One larva was collected June 2o,• at a pond margin at Straight River. Most of these larvae accepted various types of food at the laboratory. Pupation occurred from May 3 to July 10, and adults appeared May 14 to July 26, the period varying between 10 and 17 days. Larva 26 to 33 mm. when mature. Head capsule of last exuvium, 3.7 by 0.54 mm. Entirely white, no maculations other than the dirt-filled pubescent areas. Dorsum and venter smooth shining, striated laterally. Siphon moderate in length, finely striated. An easy larva to recognize; the only all white larva taken except one specimen of a terrestrial species that had unswollen tracheal trunks and was striate dorsally and ventrally as well as laterally. Pupa 17.5 to 23 mm., dark brownish. Frontal carinae prominent, contiguous mesally in the male, slightly separated in the female; rugose above. Abdominal fringes notably slender, bristle-like. Anal segment of the male is presented in Figure 18. The larvae and pupae were also reared by Cameron (1926) and Stone (1930). 32 MINNESOTA TECHNICAL BULLETIN 80

Tabanus reinzvardtii Another species has larvae fairly numerous in the same environment in Hennepin and Ramsey Counties as the two preceding. The mature larvae are most abundant from the middle of April to the end of May, but occasionally have been collected at pond margins as late as early July. All but one have accepted proffered food before pupation, which event occurred May 30 to July 7. Emergence took place from June 14 to July 18. Pupation occupied a period of io to 16 days under laboratory conditions. Larvae 30 to 40 mm. The ornate larvae of this species are easily confused with those of trimaculatus. Their separation is mentioned under discussion of the latter and Cameron has adequately described and figured it. It is also discussed by Stone (1930). Pupa 17.5 to 25 mm. in length, pale ochreous. Frontal carinae and setiferous tubercles prominent. Spinose fringes moderate, not especially stout nor slender. The distinctive feature, mentioned in the key in Part II, is the incomplete condition of the ventral fringes laterally on the second, third, and fourth segments. Some specimens with only half a dozen ventral spines in the middle of the second. Anal segment of the male is shown in Figure 16. Tabanus lineola Only four larvae of this ubiquitous species have been taken. These larvae were captured near margins of temporary ponds on three occasions in Ramsey County and once under debris along a lake shore at Vining. Collections occurred from April I I to June 3. Two of these larvae refused food, the other two accepted living snails and bits of earthworm. Pupation occurred between May 17 and June 16, and emergence June I to 30, the period lasting 14 days in each instance. This larva has the unusual feature for Tabanus of a terminal tracheal spine. Larvae are whitish, 20 to 25 mm. in length when mature, moderately ornate, dorsal and ventral areas smooth, striate basally, more so on the abdomen. Smaller size and whitish hue with less extensive markings usually separate these larvae with little difficulty from stygius, which is the only other known species in Minne- sota with a stigmatal spine. Pupa 17.5 to 20 mm., yellowish to ferruginous brown. Frontal carinae rather low, widely separated; rigosity very much reduced above. Antennae rather pointed, barely' reaching head margin. Spinose 'fringes of abdomen rather sparce, slender. Dorso-lateral combs wanting, lateral with 2 to 4 short spines. Teeth of aster rather short, middle pair stout basally. Figure 12 represents the anal segment of the male. Immature stages were also described by Hart (1896).4 Tabanus iliotus Larvae of this species were collected only at the margin of an extensive artificial body of water accumulating as waste in a depression bordered by railroad fills and by a rather low bluff occupied by resi-

4 See footnote 3, p. 25. THE TABANIDAE OF MINNESOTA 33 deuces at Prior Avenue, St. Paul. The larvae were collected under debris on a gentle slope with almostno growth of aquatic plants in the shallow water beyond. They were also taken around an adjacent slough containing considefable emergent vegetation. These localities were more than a half mile within the city limits, but the reasons for not finding trimaculatzts, nivosus, or reinwardtii breeding in this locality in the same abundance as in similar situations outside_ the city are not apparent. Mature larva, 24 mm. Head capsule of last exuvium, 3.3 by 0.45 mm., dark brown. Larvae in life, yellowish amber, translucent, with series of dorso-lateral short dashes on all thoracic and abdominal segments, except occasionally missing on the last. Striae moderately coarse laterally on the thorax, and all around abdominal segments, finer on siphon. Smooth, shining areas on dorsum and venter of thorax, reduced striae posteriorly. A faint stripe connecting dashes across dorsum anteriorly of the thoracic segments, and a faint band =sally around the siphon. Tracheal tubes chitinized almost to fore margin of anal segmen't in cast skins. Lips of posterior spiracle light brown, fairly convex. No lateral spots on anal segment: Pupa 17 to 18 mm., yellowish brown, darkening on disc of thorax to fuscous. Frontal carinae low but distinct, subcontiguous mesally ; the ridge indented laterally. Rugose areas above. Frontal tubercles small, smooth; antennae not quite reaching head margin. Disc of thoracic spiracle rounded, rima rather short and unusually broad; very strongly hooked cephalad. Fringes of spines on abdominal segments reduced in number, usually 3 to 5. Anal fringe of male, 9 or more on each side. Teeth of pupal aster rather slender, prominent (Fig. 17). Dorso- lateral combs with 3 to 6 spines, frequently with small spines among the larger. Tabanus epistates Only three larvae of this species have been taken, one in the earth of a fresh gopher mound, well above the water line in a draw below the agricultural college and two in association with the preceding species at Prior Pond, St. Paul. One larva measured 28.5 mm. when stretched out. They were collected May 18 in the Agricultural College pasture draw and May 22 at Prior Pond. None of them accepted food. Pupation occurred before the larvae were studied, May 25, June 2 and 3; emergence, June 9, 14, and 16, two females and a male appearing, respectively. The pupal period occupied 12 to 15 days. Pupa 17 to 19.5 mm. Frontal carinae low, ridge continuous on either side, rather rounded and not silicate laterally, gently arched, and tapering gradually to the sides; subcontiguous mesally. Rugose lines above rather regular, radiating from between the carinae below. Frontal setiferous tubercles rounded smooth. Antennal sheaths with tip just reaching margin. Long spines on abdominal fringes absent in the middle dorsally, increasing laterally on the hind segments. Lateral combs on anal segments with more spines than dorso-lateral comb. Latter with 2 to 4 spines usually. Middle pair of teeth on aster very long, rather slender (Fig. 14). 34 MINNESOTA TECHNICAL BULLETIN 80

Tabanzts trispilus A single larva collected near New Brighton, Anoka County, in sod of an ant-hill hummock near a tamarack bog, May 15, 1926. No open water in near vicinity. The pupa was found May 31 and the adult emerged June 12. Mature larva 2.5 mm. Head capsule of last exuvium, 4.2 by 0.63 mm., light brownish. Whitish larva with faint annuli due to dirt in pubescent pads on abdominal segments. Moderately coarsely striated over whole body, including thoracic segments; striae a little finer laterally on the thorax. Prothoracic collar rather wide, yellowish. Anal segment without maculations, siphon short and finely striated. Lips of posterior spiracle narrow, yellowish, flattened. Tracheae of shed skin chitinized, less than half length of anal segment. Pupa 19.5 mm., ochreous. Frontal carinae very much reduced and widely separated. Rugosities above almost absent. Antennae short of margin. Disc of thoracic spiracles rather low, the rima gently arcuate, and practically not at all hooked cephalad. Dorsal long spines of abdominal fringes confined laterally, the short spines stout. Combs on anal segment extremely reduced, 2 to 3 short spines. Middle pair of teeth on aster very long, slender (Fig. 15).

Chrysops initis This species of deerfly breeds abundantly in the northern part of the state. Considerable numbers of larvae and pupae were taken on the shores of Lake Bemidji, T3eltrami County, June 19, while only a few were found two weeks later, July 6, 1925. Quantities of driftwood and sawdust had accumulated along the beach as the result of lumber- ing operations in the vicinity. The larvae appeared to prefer the accumulation of the frass along the beach in which to pupate. All larvae were mature, no younger instars being taken. The pupal period occupied 9 and lo days in the laboratory, emergence occurring from June 26 to July 19. All refused food. Larvae 19 to 23.5 mm. (Two were unusually small, 17 and 15 mm., pupating with the rest without taking nourishment.) Head capsule of last exuvium, 1.95 by 0.54 mm. Anal segment with posterior band rather narrow, abruptly projected laterally to include the anal margins. Dorso-lateral markings merged on the anterior portion to form a blotch, which Cameron (1926) aptly termed "mitten- shaped." This is occasionally continuous with the ventro-lateral area. Incisure narrowly banded usually hidden by the furrow in living larvae. Pupa 13 to 16 mm. Two otherwise typical pupae only 11.5 mm. Frontal carinae strongly developed mesally but not contiguous; a dip in the carinal ridge laterally makes the outer, more reduced portion less than half the extent of the inner. The ridge at this point may or may not be completely divided by a sulcus. Frontal tubercles just above the base of the wing sheath usually with a 'single, infrequently with double bristles. Spinose fringes on abdomen relatively slender. Anal fringe on male with 14 to 24 spines, on female 2 to 6 on either side. This species is extremely variable in this respect but the usual condition is about 16 in the male and 4 in the female. Cameron (1926) figured both stages of this species. THE TABANIDAE OF MINNESOTA 35

An interesting parasite, Diglochis occidentalis Ashm., was recovered from the pupae at this time, also. None was found to have parasitized the mature larvae or prepupa, altho this may have happened, as no dissections were made.

Chrysops carbwzarius Three pupae were taken among those of C. mitis at Bemidji; one adult female emerging July 6 was collected June 19; two others emerged July II and 12 from pupae collected at the same place on July 6. Stone (1930) has described the larva and pupa of this species concerning which there has been some doubt as to its separateness from mitis. The differences in the larvae are, however, striking in the lack of a terminal spine and in arrangement of maculations.

Chrysops excitans Two sources of this species were located, a lone larva being collected under debris along a lake shore at Vining, June 3, 1924, and several along the margin of a temporary pond near St. Paul, May 4, 1926. All the latter were found in a restricted area of sandy beach on the windward side, and just at the edge of the sod about one foot above water level of a fairly steep slope. They were apparently just migrating at this time, as a careful collection later in the week produced only one larva near by. C. aestuans occurred in an adjacent portion of the beach where the substratum was black muck with much organic matter, but no excitans were found under the latter conditions. Pupation was observed without further feeding in the laboratory from May 7 to June 16, adults emerging May 16 to June 24. Larva 18 to 23.5 mm. when mature. Greenish in life. Markings on anal segment reduced, the band narrow all around, not connected with the anal margins ventrally. Dorso-lateral spots isolated and a moderate annulus at the anterior incisure widening on the dorsum to an oblong blotch. Pupa 16 to 17 mm. Frontal carinae low, obsolescent laterally, the sfront rather smooth, tubercles small but still beset with 2 bristles, the inner one the smaller. Spiracular disc rather elongate, rima not strongly bowed nor hooked. Fringes on abdomen with slender spines, shortest on basal segment. Female with 5 to 7 spines in anal fringe. Male, according to Cameron (1926), has about two dozen spines in anal fringe. No male available in the material reared at this laboratory. Chrysops striatus One larva was collected June 3, 1924, near Vining, and one on May 4, 1926, near St. Paul in association with the larvae of the previous species. • Several larvae were also taken April 25 at the Golf Ponds along a reedy shore line. The larvae were unfortunately not studied before pupation occurred and an accident destroyed the larval pelts, but Stone has described the larva and pupa. None of them accepted 36 MINNESOTA TECHNICAL BULLETIN 80 proffered food. The first larva pupated June 7 .and a female emerged June 17. The others pupated from May 14 to June 16 and emerged June 5 to June 24. Pupa 8.5 to io.5 mm. Frontal carinae very distinctive; extremely prominent mesally, strongly and evenly arched, narrow at base; lateral portion obsolescent, in contrast; little rugosity on front above. Spinose fringes on abdominal segments very short, reduced on the dorsum of the second segment to mere points; those on the seventh segment rather long by contrast as compared with the usual relation of spine lengths between the basal and distal fringes. Anal fringe in male with 16 to 18 spines and the female with 4 to 5 on e:ther side.

Chrysops montanits Several larvae were collected along the shore of Gull Lake, in Cass County, June 19, 1924. Two were observed to feed upon bits of earthworm which had been offered to all. Pupation occurred in two instances June 23 and 24; the rest pupated June 29 and 30. The pupal period lasted 10 to 15 days, except in the case of two females, which did not appear until after 19 and 20 days. Also reared by Stone (1930). Larvae 13 to 14.5 mm. when mature. Pale ivory or whitish in life. Macula- tions on anal segment rather heavy, posterior band sloping irregularly vdntrally and forward to envelop the anal tubercles. The band may be separated from the anterior margin, or with ventro-lateral projections to it. Dorso-lateral spots usually confluent and connected to the anterior margin of the segment. The striated, clear spots in the posterior band mentioned by Stone are variable in extent in larvae seen - by the writer. The whole anal segment and siphon rather short and bluntly rounded; latter with protrusile spine. Pupa 10.5 to 13 mm. Frontal carinae somewhat variable, usually low, obsolescent laterally, infrequently prominent mesally, subcontiguous. Spinose fringes on abdomen composed of short spines, stout at base, sparcely spaced roughly about the basal width of the sines themselves. Spines 12 to 20 in anal fringe of male, 4 to 5 on either side in the female. Anal segment of male pupa shown in Figure II. Chrysops aestuans Numerous mature larvae of this species were collected in May, 1924, along the banks of a temporary pond near the Agricultural Col- lege, arbitrarily known as Golf Pond No. 2, in local ecological studies. They measured 18 to 20 mm. in length and all refused food. One larva was also taken at Prior Pond near the locality infested by larvae of 7'. illotits and epistates. Pupation occurred May 23 to June 9 and adults of both sexes appeared June 3 to 21. The pupal period lasted II to 13 days. Two larvae were taken October 31, 1930, in muck at water level just under a frozen margin of a permanent pond. The gut in each was distended with a reddish material appearing to be derived from chironomid larvae, which were very abundant in the same situations. One of these larvae was killed. The other was placed in a THE TABANIDAE OF MINNESOTA 37

beaker and kept submerged for over a month at room temperature without ill effects or signs of distress. Unboiled tap-water was used originally and for replacement as evaporation occurred, so that there was considerable dissolved oxygen available for respiration if accomplished in the manner suggested by Stammer, through the skin. No bubbles were allowed to accumulate on the sides of the glass. When the level of the water was lowered, in early December, the larva showed no signs of eagerness to take air through the siphon after this long submergence. It was obviously restless, however, and was found one morning to have attempted to pupate after evaporation had reduced the moisture to a mere wetting of the larva. The smooth sides of the beaker prevented traction and an imperfect pupa resulted. The high laboratory temperatures had obviously stimulated pupation in the "cold-hardened" larva from the field, as in fall-collected larvae of C. indus mentioned later. It appears that the present larva was able to restrict the urge to pupate in spite of the higher temperatures, until reduction in the amount of water indicated availability of air for the prospective pupa. The remarkable shrinkage preceding pupation is well shown in measurements of one specimen, 20 mm. when taken May i i and only 14 mm. 2 weeks later in the prepupal stage. Larva 19 to 23 mm. in length, whitish, with dark annuli. The posterior band on anal segment dorsally broad, frequently with projections dorso-laterally ; band widening gradually on the sides to include the anal margins. Frequently specimens show a fading ventro-caudally. Anterior dorso-lateral spots usually isolated. Pupa 12 to 15 mm. Frontal carinae usually strong, undivided laterally altho frequently a strong dip in the ridge or a complete separation with the lateral and median portions subequal. Fringes with sparce stout spines on abdomen. Anal fringe of male robust, 8 to ii spines, female with 3 to 5 on either side. Cameron (1926) has described the immature stages of mocrcns- (= acstuans). Chrysops callidus A few larvae were taken at the Golf Pond in ,association with the previous species and one was taken in the draw in the college pasture in the vicinity of T. trimaculatus principally. The latter was 19 mm., but the rest were not more than 17 mm. One was 17 mm. on May and had 'shrunk to 13.5 mm. on the 22nd, 3 days before pupation. The latter event was recorded May 21 to 25 and emergence in io to 17 days later. No detectable difference in the pupa was observed except a slightly smaller average length, i i to 14 mm., from the pupae of C. aestuans. Figure 20 represents head shield of pupal shell. Hine (1903), Marchand (1917), and Stone (1930) have discussed various stages of this species. 38 MINNESOTA TECHNICAL BULLETIN 80 .

Chrysops iildus Only a few larvae of this species were found during the collecting seasons of 1924 and 1925. But they were in some abundance in larval collections in 1926. Notes on abundance, of adults are not available for this vicinity in 1924, but in the following year the writer took the females in considerable abundance in June, especially in small patches of shady woods along certain creeks. On June 14, 1925,, in woods along Rice Creek, Anoka County, for example, 66 females were taken about the person of the collector in about 3 hours, while of the next most abundant species, C. callidus, only 18 were captured. Larvae at this time were not so abundant as they were the following year in the muck along this creek, when 24 were taken in a short time on May 6. The same results were obtained along Coon Creek. The association of an abundance of flies one season and of larvae in the same locality in the next is not necessarily significant except as a result of several seasons of study in the same locality. Some temporary ponds with partial shade from adjacent woods also yielded larvae of this species in 1926. Two larvae were collected Octo- ber 25, 1925, in one of these situations when a very little water had accumulated from fall precipitation. They had been subjected to some freezing weather, the mean temperature for October being 56.5° F. and the mean minimum 30.5° F. They proceeded to pupate and emerge when brought into the laboratory, whereas some Chrysops larvae similarly handled in the'laboratory but collected in mid-summer had merely become dormant. Occasional mature larvae of this species have attacked fragments of earthworm and fly maggots but most have pupated without accepting food. Larvae are collected chiefly in April and May. Pupation occurred •from May 9 to June 16 and emergence of adults from May 24 to June 27. Pupation of the two late fall specimens occurred Novem- ber i i and 20, and both emerged December 6, two females appearing. This species was also reared by Stone (1930). Larva 15 mm. Of the usual Chrysops type, whitish with dark annuli. Pos- terior anal band rather broad, usually two triangular forward projections dorso- laterally. Band slopes downward anteriorly to envelop the anal region to the front margin of the segment ventrally. A pair of isolated lateral spots and a broad, black band above these running across the dorsal anterior margin, deeply notched in the middle. Pupa 9.5 to 13 mm. Frontal carinae prominent, divided laterally by deep sulci making the median and lateral portions subequal ; infrequently the carinal ridge is continuous with a definite dip but usually discontinuous at the sulci. Disc of thoracic spiracles rather narrow, about as wide before as behind. Spinose fringes composed of spines that are relatively slender, not so much as excitans but more slender than in aestuans and callidus; anal fringe of male with about 16 to 22 spines, female 4 to 5 on either side. THE TABANIDAE OF MINNESOTA 39'

Chrysops sackeni Two larvae were taken along the draw in the college pasture, May 17, 1924. They measured 17.5 mm. and steadfastly refused proffered food. Pupation occurred May 24 and 27 and an adult male and a female emerged June 7 and 10. Several others were taken in 1926, May i i to 17, along temporary ponds both within the city limits of St. Paul and along the county .roads. They were nowhere in any abundance, however. The pupal period in these was also .between To and 13 days, the last fly emerging on June 18. Larva 16 to 18 mm., whitish. Markings of anal segment distinctive, reduced. Lateral and dorso-lateral maculations linear. Posterior band on anal segment rather narrow, abruptly produced ventrally to meet the anal margins only narrowly. Pair of narrow lateral projections extending to a point just above the upper corner of the anal margin. Faint annuli on the anterior incisure, widening into dark blotches just in front of the linear lateral spots. Siphon with a light ring basally. Pupa 11.5 to 13 mm., light yellowish. Frontal carinae prominent mesally but not contiguous, usually obsolescent laterally; infrequently the carinal ridge is extended across the usual position of the sulcus, but lateral portion ,low, not produced. Rugosity usually reduced above. Width of thoracic spiracle somewhat variable but usually subequal before and behind. Fringes on abdomen composed of extremely small, fine spines especially on the basal segments. Anal fringe in male 16 to 20 spines, in female 3 to 5 either side.

Chrysops wiedentanni One larva of this species collected from the same locality as the preceding species in the pasture draw of the college, May 8, 1924. It accepted bits of earthworm and oligochaetes until May 29. On June 19 it pupated, an adult female issuing on June 26. The larva was not studied before pupation occurred because its small size was considered as indicative of immaturity. Discussed by Stone (1930). Pupa 9.5 mm., pale yellowish. Front with rugosity reduced to a minimum, only the inner carinal ridges apparent as low rather smooth elevations widely separated medially, completely disappearing laterally. Frontal setiferous tubercles reduced but rugose. Disc of spiracles narrowing somewhat cephalad, inferior margin with very reduced serration; rims prominent, arcuate not strongly hooked. Dorsal fringes on abdomen composed of stout, short spines, evenly spaced about the width of the spines apart. Anal spines of female with 4 each side. No male available. BIONOMICS OF ADULTS Most of the bright colored, pictured-winged deerflies, the smaller flies of the family, are especially partial to woodlands and timber. It is here that the deer and wild game fall a prey to their attacks. They are nothing loath, however, to assail man himself, attacking him with the same avidity shown for stock and game, in marked contrast to the 40 MINNESOTA TECHNICAL BULLETIN 80 habits of the larger horseflies of the genus Tabanus in Minnesota.5 The generic name Chrysops is derived from their beautiful golden yellow or iridescent greenish eyes with purple markings. The colors of the eye disappear soon after the death of the inseet. While most of them, like C. mitis in the north and C. montanus near the Twin Cities, are more prevalent in and about the woods, several species may be found in open country also, especially about swamps and ditches where they breed. C. sackeni, for example, have been taken among the Fridley Sand Dunes in Anoka County and about Moore's Lake, an extensive, unsheltered marsh bordering the dunes. Bathers are often bothered by deerflies and during observations in the summer of 1924, large numbers of them were to be found about the summer, resorts at International Falls, Bemidji, Minneapolis, and Geneva, localities representing almost a longisection of the state. C. mitis was the most abundant offender in the north, C. striatus and C. sackeni replacing ,it as the dominant species in the south, during the periods of observation. The more somber and larger horseflies in the northern sections do not seem to penetrate the woods in the "same numbers as do the. deerflies. They do, however, congregate in the edges of the forests. Anyone having occasion to go near the woods is quickly aware of their presence by the peculiar hum or rustle of their wings as they circle about the head. The insistent hum of the larger tabanids is readily distinguished, but the approach of a deerfly is frequently missed before it alights or begins feeding. It is surprising, however, how quickly the ear of the tabanid specialist becomes attuned to the characteristic and usually unnoticed flick of a deerfly -about the head. Numbers can be captured by a vigorous swinging to and fro of the net in the air as they circle about the collector. During the observations near the forest at International Falls, 252 specimens of both Chrysops and Tabanus were captured in this manner in an hour and a half. T. astutus and C. mitis were the species most numerous in their respective genera at this time. Repeated attempts were unsuccessful to induce the species of Tabanus to bite by allowing them to remain on the bared forearm, where they were alighting in numbers. Altho these tabanids were swarming about in considerable numbers and seemed very persistent in their attacks upon stock, they soon took wing after resting on the bare skin of the collector for a short time. Species of Chrysops were not so backward, however, and took advantage of every opportunity offered, especially while both hands of the

5 In this connection it is interesting to note that while the species of Tabanus are seldom observed to bite human beings in Minnesota, the writer has observed many species that are energetic in seeking out the luckless hiker who crosses their haunts in Montana and other western states. THE TABANIDAE OF MINNESOTA 41

collector were engaged in procuring specimens from the net. Experi- ments in attempting to allow the larger horseflies to feed on the bare arm were frequently terminated abruptly by these persistent little visitors. More species were taken during this one period of 3 days than were captured in a similar period in any other locality. This was despite the fact that the day previous was the first bright, warm weather because of an exceptionally late spring. The following species were tal.en at this time : Chrysops carbonarius, C. cxcitans, C. indus, C. lupus, C. mitis, C. nigcr; and Tabanus astutus, T. affinis, T. illotus, T. lasio- phthalmits, T. mctabolus, T. nudus, and T. zonalts. Haematopota americana was observed but not taken. T. astuitus outnumbered any other tabanid 2 to I, and because of its numbers was the most annoying to stock. A peculiar habit, especially of the species of Tabanzts, was noted at this time. The spring had not only been late but had also been exceptionally dry; in the cultivated and cutover tracts south of town, very little standing or open water was to be found: A drainage ditch and two small roadside puddles offered the only open water in the neighborhood. It was noticed that almost as early as tabanids were about, some would be dipping at these pools. From a point of vantage overlooking the pools, 132 T. lasiophthalmus, 6 T. affiinis, 13 T. nudus, and 2 T. zonalis, all males, were captured during the 6 or 7 hours of the last two days spent about them. Visitations by females were very infrequent, as were those of either sex of Chrysops. Night activities.—Despite the partiality to the protection afforded by woods shown by most species in the north, as a general rule all our tabanids are lovers of warmth and sunshine; at least, no crepuscular forms hav.e been observed at flowers or bothering' stock. The following specimens of both genera have been taken at lights, however: C. callidus—University Farm, St. Anthony Park, July 5, 1923. I female. C. striatus—near Shakopee, July 14, 1922. I female. T. actaeon—St. Peter, Sept. I, 1922. I male. T. trispihts—St. Peter, July 21, 1922. I female. T. septcrtrionalis—St. Peter, July 21, 1922. 1 female. It is probab!e that these individuals had put up for the night on some near by object from which they were enticed by the brilliance of the light. At night horseflies appear to seek the protection of plant ,foliage and trunks of trees or nearly any inanimate object offering good footing, where they remain until the warmth of the .sun induces them to begin the activities of another day. They may occasionally also be seen resting during the daytime, especially after feeding, on som fence or telephone pole, a, convenient rock, or other object. The males of many species and newly emerged females are frequently swept from grass MINNESOTA TECHNiCAL BULLETIN 80 and vegetation near their breeding places, as has frequently been mentioned in literature. Both the males and females of T. lineola have been observed several times resting head downward on telephone poles, even in city limits a considerable distance from water. Hine (1906) and Patten and Cragg (1913) also mention having observed this habit. Mitzmain (1913) seems to have had extremely fortunate conditions for detailed observations on the daily activities of T. striatus Fabr. "Dur- ing the cooler part of the day the flies assemble on the trunk and main branches (of rain trees), but when it is sunny the upper and lower limbs and leaves are resorted to; on windy days they may be found at all hours perched on the side of the trunk of the tree shielded from the wind." Isaac (1925) limits the activities of this species to a period at sunset. The habit of the females of following trains as noted by Lugger, Hine, and others is readily observed in northern Minnesota; they can easily keep up with a train for several miles at an estimated average speed of 35 miles an hour. They. may be noticed to make excursions to one side or the other and then dart back to resume their former position 'of flight beside the car window. An occasional specimen will even light in a sheltered spot on the outside of the car or fly in at the open window. McAtee and Walton (1918) mention observing Tabanus ac/aeon darting through the openings in a cabin in the woods, following the latter enigmatic instinct. Mosier and Snyder (1918) and others have called attention to the peculiar habits of certain horseflies of entering cars and dwellings. The enormous numbers picked from windows in cabins, by Lugger, was mentioned earlier. This habit renders very easy the collecting of certain species. During a horsefly survey trip in a closed automobile in the summer of 1925 through certain parts of the state, one method of obtaining adults was that of leaving one door partially open. Large numbers not entering the car were netted off the fenders and warm tires or caught while circling the car. Most of them did not seem much interested in trying the nutriiional value of the car, only a few making desultory probes after alighting, the majority merely stroking their front tarsi together or over their heads, or brushing their wings with the hind legs. Heat seems the chief attraction, as they seek the warmest spots on the car. Tires recently heated by running are more attractive than those that have cooled or stood for some time. However, in entering apertures they are obviously responding to another unknown urge. Tabanus lineola, 7'. septentrionalis, and the members of the affinis group are the species mainly attracted to buildings. Occasional specimens of T. zonalis, Chrysops lupus, and C. mitis are thus taken also. During the survey made in Roseau County, specimens of. most of these species were picked off the station windows at every stop made by the THE TABANIDAE OF MINNESOTA 43

train. The farther south the train proceeded the fewer were the tabanids in the station waiting rooms. Motion and color have an appeal, also. Horseflies seem especially attracted to dark objects, as shown by their preference for the darker cows, or darker spots on a cow. At least it does seem not merely coincidence that, during several observations, the dark red and black cows of the University dairy herds shared almost exclusively the attention of the comparatively few horseflies observed attacking cattle in this vicinity. This has also been noted by Graybill (1914). Hine (19o7) calls attention to the preference shown by horseflies in Louisiana for certain individual animals, seldom attacking others in the same herd. He states, however, that neither differences in resistance nor color of the hosts seem to offer any satisfactory explanation for this selectivity on the part of the flies observed by him. A coat placed on the ground or the dark hat of the collector furnished attractions for both the deerflies and the horseflies; several species have been taken in this manner on warm days near St. Paul. Motion apparently attracts the attention of horseflies in flight, after which odor or warmth seems to cause them to alight. Almost any moving object will cause them to hesitate for investigation in passing. They have been observed to circle about the person of the collector and then alight on a near by cloth used to rub down cattle. Mating.—The writer has never observed the mating of tabanids, and few references regarding this phenomenon have been located. Hine (1903) records observations on the sexes of Tabanzts sulcifrons in copu- lation and indicates that the period during which mating takes place is a short one. He mentions one or two pairs dissected which contained blood in the alimentary tract. Cameron (1917) reports Tabanus comastes seen in coitu at an elevation of 8,5oo feet. Neave (1915) is inclined to the opinion that the females remain around the breeding place until after pairing and the subsequent death of the males, before feeding or oviposition takes place. A peculiar practice of swarming of T. aincricanus (mostly males) in the early morning hours, as observed by Mosier and Snyder (1918) in Florida, was neither proved nor dis- proved as involving mating of that species, altho observed repeatedly for 2 years. Webb and Wells (1924) however, have recorded a few observations of mating in T. phanenops, the individuals coming together in the air and usually alighting on a grass stem. This occurred between 8 .and 9 o'clock in the morning. Our attempts to get bred adults to mate failed, even in a large cage in quite natural surroundings. Other workers seem to have been equally unsuccessful. On July io and 12, 1925, an opportunity occurred for watching some activities of the males of Chrysops and of T. illotus among the 44 MINNESOTA TECHNICAL BULLETIN 80

rank grass and vegetation margiinir4_,, Moore's lake, Anoka County. Following are the field notes as made at the time: "July io. Day clear, bright, temp. 79, low humidity and no precipitation during any part of the day. Breeze from the south. Time spent between 9:30 and 10 :30 a.m. Situation at south end of marsh between forks of highway; low, wet, over- grown around margin with tall grass, succulent herbage, and willows on all of which aphids were breeding profusely; cat-tails beyond, leaving practically no open water. Stock on adjoining farm about a mile away, but none in immediate vicinity. Males of both Chrysops and T. motifs were noticed, the former along with the females were licking at the aphid-infested stems of the plants. Some Chrysops males were also found visiting the sticky pinkish flowers of milkweed. Female Chr,ysoPs rather prevalent about collector, especially as a rapid movement through the grass seemed to stir them up. Some males taken by sweeping, but only one female. Majority--C sackcni. The males of T. Motifs were also observed sitting about on grass and leaves exposed to sun and generally over shallow standing water. They were seen to dart up as if chasing something and then return to the same or a neighboring leaf. Four males were seen for a time in about 3 square feet of space, one on a Sagittaria leaf, each of the others using grass blades in this restricted area to rest upon and return to. "July 12. Day murky but not cloudy, temp. 73° to 78° during stay from 9:30 till noon. Precipitation 0.7 in., for day. Situation as described on ioth, no stock in immediate vicinity. Males of both Chrysops and T. illotus noticed in same abundance all during time spent except that the males of Tabanus seemed to diminish about noon. On arrival 5 illotits males were noticed in same location of about 3 square feet as on previous visit. Altho others were noticed elsewhere in similar situations, i.e., breaks of Sagittaria and other plants among the tall grass "carpet," they did not occur in the same concentration. All except one on grass near the road, were down toward cat-tails, which were in shallow standing water among the vegetation. The five mentioned above, closely watched at intervals all a.m., diminished to one about noon. They varied their position Nv it hin this space but always returned to it following a quick dash .after some indeterminate object. Lat- ter never determined. On returning, two or three would be closely following each other and would often alight on the first one to come to rest as if seeking copula- tion. They would immediately assume a still pose on their perch, the body slightly elevated anteriorly, the abdomen usually touching the leaf behind, with the genitalia slightly protruding. In this pose, the front legs were usually doubled up under- neath and not grasping the perch, but raised as if in a tact:le or sensory position of some sort. Immediately after alighting they took a firm hold with the four posterior legs and rubbed the anterior legs together but never stroked the head as houseflies do. At the approach of some interesting specimen, they ceased stroking the tarsi together and lowered legs, elevating the knees in short jerks, acting as if trying to sense something before taking off after it. The object of their sorties could not be ascertained; the shorter dashes, when followed, seemed to be out and back for an unseen or for no particular object. Two or three times a female tabanid whirred around me and attracted a frenzy of attention on the part of the males, flying up and away after the departing female but their chase could only be followed with the eye momentarily. Once in a while an unidentified female would attract no notice, perhaps being of another species. One wonders if a. tuning fork of the right pitch would cause simultaneous reaction. It was occasionally noticed that a male would drop his front legs and start crawling, at which time no notice was taken by it when the others darted off in pursuit of something. THE TABANIDAE OF MINNESOTA 45

One was noticed to crawl down into the base of the vegetation and lap up a drop of dew or respired mOisture. No aphids at that place. "Fewer females of T. illotus were seen than males, and then only about the person. Males of C. sackeni were observed less frequently than those of Tabanus, and were perched about on the shady sides of the grass blades and usually most numerous farther out toward the cat-tails in the swamp. Those noticed were either still or wandering about lapping at the dew in among the grass. Only one was noticed to have its front legs elevated in the position of waiting seen in Motus. Several others seen in a still attitude would suddenly dart away and not return to the same spot. For some reason, neither sex seems interested in the aphids today. "It may have been only a coincidence that when males of illotits dropped their front legs on the perch but remained in the waiting position, the left leg of those seen was always well back toward the next leg and the right one was well advanced." Blood meals.6—The methods of feeding have already been discussed; more detailed accounts may be found in Patton and Cragg (1913). The idea of a periodicity in taking blood is expressed both by Mitzmain (1913) who observes Tabanus striatus to bite not oftener than once in 2 days, and by Patton and Cragg who say that "judging from experiments carried out with tabanids in captivity, they appear to feed every three days." The difficulty in getting bred specimens to bite is mentioned by them and other ,authors and reared females of Minnesota species both of Tabanus and Chrysops were never induced to bite. Those caught in the open seemingly bite experimental animals with great reluctancy, altho they accepted rather eagerly, sweetened solutions sprinkled about their cage. The statement has often been made in the literature that the females must have a meal of blood before oviposition can take place. The evidence for these assertions has not been located, unless it is postulated on the basis of experiments with mosquitoes. There is little evidence as to the length of the natural life in either sex. Neave (loc. cit.) believes the existence of the males as adults to be short. Nieschulz (1927) observed a longevity in caged T. mbidtts and T. striatus of 70 days when given ample opportunities for feeding. The length of natural life prob- . ably varies according to the region and climatic conditions. Mitzmain (1913) makes the statement that "judging from the longevity of .females kept under laboratory conditions, it appears that a diet of blood is essential for the development of the eggs." But it is not clear how his subsequent experiments apply, as none of the flies are recorded as having oviposited or having been dissected. Captives of both sexes, fed on their natural nourishment, viz., fresh gum of the

6 The percipitin method is well adapted for determining the host of a given blood meal in tabanids, the greatest difficulty being the finding of the resting places of recently engorged females. A specimen of Tabanus socialis, which was captured by the writer at lights at night in Nigeria, gave positive test for bovine blood (Davis, G. E. and Philip, C. B., 1931, The identification of the Wood-meal in West African mosquitoes by means• of the percipitin test. A preliminary report. Jour. of Hygiene, Vol. XIII, No. 3, May). 46 MINNESOTA, TECHNICAL BULLETIN 80 rain tree, lived a maximum of 14 days. Bred females given blood meals lived a maximum of 18 days and an average of io days. The captive females outlived males by several days. During attempted oviposition and mating experiments at Minnesota, captive females of T. lineola and T. lasiophthalmus in a large outside cage in natural surroundings, lived an average of about 8/1 2 days, a few reaching a maximum of double that number during cool weather. The imaginal period before capture was probably quite variable, altho the individuals used appeared in good condition when liberated in the cage. Bred specimens of C. aestuans and C. mitis survived only 5 days in this cage. No eggs were obtained. Flower visitation.—It is a well known fact that tabanids thrive on other food than blood and upon occasion certain species show a decided preference for the nectar from blossoms, i.e., Buplex rasa Loew mentioned by Hine (1903) and Stone (1930). Hine has suggested that the former idea that females were compelled to visit flowers when unable to find a blood meal is probably erroneous, it being more likely a matter of choice on their part. Speaking of T. sulcifrons, he quotes (1906) "I am thoroly convinced that the females take much other food than blood and do not believe it would be overstating the facts to say that specimens of this sex may pass the period of adult life without taking blood at all. It is as yet difficult to verify the common statement that a blood-meal is a necessary precedent to development of the eggs, and it is likely a matter of variation with different species as in the mosquitoes." He also took C. montantts on blossoms of Cornus. Hart (1895) lists T. venustus, T. lineola, and 7'. costalis as taken on flowers. Mosier and Snyder 0918) record both sexes of T. ameri- canus, 7'. trijunctus, and T. lineola as feeding at several kinds of flowers but chiefly the blossom of the saw palmetto. McAtee and Walton (1918) mention taking T. melanocerus and T. trispilus females on Ceanothus. Bequaert and Davis (1923) found the females of C. plangens visiting flowers of Chrysanthemum leucantheunt. Practically all other references to flower visitation by nearctic species have been general without definite citations. A male of C. aestuans and a female of T. metabolzts were taken on alfalfa blossoms in Swift County (Carter) in this state. The writer found a male of T. epistates and 19 males and 9 females of T. bicolor and a female of C. htpus on the bloom of the Canadian thistle at Clear River, and numbers of males of C. sackozi on milkweed blossoms at the Fridley Sand Dunes (Anoka County). In addition, circumstantial evidence in the form of pollen and anthers on the probosci of 3 females of T. lasiophthalmus, and thrips adhering to the labellum of one, all taken at International Falls, point to flower visitation by some individuals of that species. Other- THE TABANIDAE OF MINNESOTA 47 wise, careful search has failed to reveal this activity on the part of either sex in this state. The males, being unable to bite, are never seen about stock. Specific references to males taken at flowers are meager and it seems mostly taken for granted in the literature that flower visitation for nourishment is a characteristic of that .sex in general. It appears peculiar, however, that more are not observed in the act, especially when one is on the lookout for them knowing them to be abundant in the vicinity, as at International Falls. If they visit flowers, as a rUle, the explanation may be that they have a preference• for some obscure blossom or visit flowers at some unusual time in the season or the day. It is conceivable that many of the males with areas of enlarged facets might be able to utilize these as "night eyes" in obtaining nourishment or during other nocturnal activities and for that reason are not frequently taken among other dipterous species on flowers. The writer has never observed tabanids of either sex on flowers during intensive night collecting for cutworm moths throughout the summer season in Montana, in a region well infested with Tabanus and Chrysops during the day. The flowers were few in species and quite restricted in this little inhabited and almost uncultivated prairie region. There are many references to the attraction of secretions by homop- terous insects or exudations of tree sap for both sexes of horseflies, i.e., Macfie (1912), Mitzmain (1913), and others. Froggart (1915), in speaking of the males, says ". . . they sometimes attack aphids and other soft bodied insects and suck up their blood but it is only the females that have the true blood-sucking instinct." We have observed several infestations of plant lice and scales which were attracting the attentions of numbers of Diptera and other insects in this vicinity when both sexes of several Tabanus species were on the wing near by, but we have never been fortunate enough to observe the larger horseflies under such circumstances, altho we kept several likely places under surveillance throughout a period of several days and at different times of day. However, both sexes of C. sackeni were once observed gathered on aphid-infested grass at Moore's Lake, Anoka County. A number of males of T. illotits were not interested.

Seasonal and Geographic Distribution In this section are presented the time and locality data for the Min- nesota specimens of each species combined under "Specimens examined" in the systematic treatment of the adults (Part II). The arrangement of the data of collection is semi-monthly for each species, the county and collector, where known, being given in parentheses. Larval and pupal collections have not been included because considered in a previ- 48 MINNESOTA TECHNICAL BULLETIN 80

ous section, which accounts for differences in certain species between total specimens examined in Part II and those listed below.

Chrysops aestitans Locality only-(Ramsey) 49; (Olmsted) 3? June-12/12 (Wilkin)? Total 22/21, Lake Owasso (Ramsey, Hoffmann) d',?; 19/22, Marshall (Lyon, Mickel) 59; 23/10 (Yellow Medicine) 9; 29/12, Foxhome (Wilkin) 16/25, La Crescent (Houston, Philip) 509s; 30/27, Jordan (Scott, Dawson) 9. Total d, 59? July-6/16, University Farm (Ramsey) 9; 1/24,. same (Philip) 9; 4/14, Coon Lake (Anoka, Kepperly) 9; 6-9/12 (Wilkin) 8?; 8/10 (Wash- ington) 9; 8/12 (Otter Tail) 2?; 9/25, St. Paul (Ramsey, Philip) 9; 9/23, Rice Street (Ramsey) 9; 14/22 (Scott, Hoffmann) ?. Total 179 19/21, St. Peter (Le Sueur) 9; 20/24, St. Paul (Ramsey) 9; 19/23, Le Sueur, Kepperly) 9; 25/10 (Pipestone) 9; 27/22, St. Peter (Le Sueur, Hoffmann) ?; 30/18, Lake Independence (Hennepin) 2?; 29/24 (Ramsey, Philip) 9. Total 8? August-2/24 (Ramsey, Philip) d; 3/24, Moore's Lake (Anoka, Philip) cr, 9; 3/15, Deer River (Itasca) 3?; 5/24, Geneva (Freeborn, Philip) 3?; 15/25, Minneapolis (Hennepin, Kepperly) ?. Total 2,8? 16/15 (Ramsey) 9. Total 9 Chrysops callidus May-20/22, St. Paul (Ramsey, Hertig) ?. Total 9 June--6/io, St. Anthony Park (Ramsey) ?; 7/25, Rice Creek (Anoka, Dawson) 9; 14/25, Rice Creek (Anoka, Philip) in; 15/25, Red Wing (Goodhue, Philip) ?. Total 21? 16/25, La Crescent (Houston, Philip)'18? ; 19/25, Moore's Lake (Anoka, Philip) 2?; 21/25, Tamarack Bog (same) 3?; 21/25, Rice Creek (same) 3?; 20 and 29/10, St. Anthony Park (Ramsey) 2?; 26/25, Luverne (Rock, Daw- son and Sweetman) 2?; 28/15, University Farm (Ramsey) 9; 22/25, Dyna- mite Ponds (Ramsey, Philip) 5?. Total 136? July-1/25, Dynamite Ponds (Ramsey, Philip) 5?; 7/23, St. Anthony Park (Ramsey, Knight) 9; 7/24, University Farm (Ramsey, Philip) 9; 8/10 (Washington) 9; 10/25, Moore's Lake (Anoka, Philip) 9; 11/21, University Farm (Ramsey, Hoffmann) 9; 14/22, Sand Dunes (Anoka, Nichol) 9. Total H9 17/18, Crystal Lake (Hennepin, Riley) 9; 29/25, Forf Snelling (Ram- sey, Philip) 9. Total 2? August-2 and 9/24, University Farm (Ramsey, Philip) ; 7/24 (same) 29; 9/24, Rice Creek (Anoka, Philip) 9. Total 59 25/13, St. Anthony Park (Ramsey) 9; 26/24, Tamarack Bog (Hen- nepin, Philip) 49. Total 59 Chrysops carbonarius June-21/24, Vining (Otter Tail, Riley and Philip) 29; 24/26, Lake City (Wabasha) ?; 28/30, Itasca Park (Clearwater, Dawson) 9. Total 49 July-5/22, Eagle Bend (Todd, Hoffmann) 9; 2-5/24, International Falls (Koochiching, Philip) 99; 6/24, Bemidji (Beltrami, Philip) 29. Total 129 August-14/18, Glenwood Park (Hennepin) 9. Total ? 29/16, Lake City (Wabasha) 9. Total 9 THE TABANIDAE OF MINNESOTA 49

Chrysops crier Locality only-Ramsey county, 9. Total 9 June-1898 (Olmsted, 'Ainslie) 9; 14/25, Rice Creek (Anoka, Philip) II?. Total 129 21/25, Rice Creek (Anoka, Philip) 29. Total 29

, Chrysops excitans June-14/25, Rice Creek (Anoka, Philip) ii?; 15/23, Stillwater (Wash- ington, Lewis) 159. Total 26? 21/26, McGregor (Aitkin) 9; 17/22, Minneapolis (Hennepin, Hoff- mann) 9; 19/24, Hackensack (Cass, Riley and Philip) ; 20/24, Park Rap- ids (Hubbard, Riley and Philip) 9; 28/30, Itasca Park (Clearwater, Daw- son) 23?. Total 279 July-1908, Itasca (Clearwater) 9; no year (Clearwater, Person) 2?; 1/21, Itasca Park (Clearwater) 29; 3-5/24, International Falls (Koochi- ching, Philip) 179; 4/16 (Roseau) 9; 10/18, Rush Lake (St. Louis) 9. Total 249 17/12 (St. Louis) 9; 23/29, Poplar Lake (Cook, Orr) 209. Total 2 August-Itasca Park (Clearwater, Dawson) 209. Total 20? 19/15, Duluth (St. Louis) 9; 22/26 (Cook, Orr) 9. Total 29 September-13/18, Burnts.de Lake (St. Louis)? Total 9

Chrysops frigidus

-June-I6/i6 (Roseau) 9; 21/21, St. Anthony Park (Ramsey, Hoff- mann) 9; 23/37, St. Paul (Ramsey, Dawson) c'; 28/30, Itasca Park (Clear- water, Dawson) 9 .Total July-9/11 (Washington) Total g 17/18, Crystal Lake (Hennepin) 9; 17/25, Clear River (Roseau, Philip) 9. Total 2? August-10/15, Deer River (Itasca) 9. Total

Chrysops fulvaster June-24/10 (Rock) 9; 26/25, Luverne (Rock, Dawson and Sweet- man) II?. Total 129 Chrysops indus May-3I/no year (Ramsey) 9. Total 9 June-6/25, Sand Dunes (Anoka, Philip) 9; 11/16, University Farm (Ramsey) 9; 5/21, St. Anthony Park (Ramsey, Hoffmann) 9; 14/25, R ce Creek (Anoka, Philip) 669; 13/10, St. Anthony Park, 9; 15/23, Stillwater (Washington, Lewis) 9. Total 719 16/25, La Crescent (Houston, Philip) 29; 17/16; St. Anthony Park (Ramsey) 29; 17/18, Crystal Lake (Hennepin) 9; 19/25, Moore's Lake (Anoka, Philip) ; 19/24, Coon Creek (same) 289; 20/21, St. Paul (Ram- sey) 9; 20/24, Park Rapids (Hubbard, Riley and Philip) 9; 28/15, Uni- versity Farm (Ramsey) 9; 21/25, Rice Creek (Anoka, Philip) 149; Dyna- mite Ponds (Ramsey, Philip) 27?; 24/29, Itasca Park (Clearwater, Daw- son) 29; 28/30, same, 99; 28/25, Rice Creek (Anoka, Philip) 69. Total 959 July-I-13/21, Itasca Park (Clearwater, Person) 29; 3-4/24, Inter- national Falls (Koochiching, Philip) 149; 4/16, Shakopee (Scott) 9; 6/27, Lake City (Wabasha, Mickel) 9. Total in MINNESOTA TECHNICAL BULLETIN 80

17/25, Clear River (Roseau, Philip) 89; 18/1o, St. Anthony Park (Ram- sey) 9; 18/25, Warroad (Roseau, Philip) 129; 18/25, Longworth (same) 29; 18/25, Red Lake Falls (Red Lake, Philip) 9. Total 24? Chrysops lupus June-25/15 (Itasca) 9. Total July-3-5/24, International Falls (Koochiching, Phil:p) 9; 15/25, Salol (Roseau, Philip) 9. Total 2? 17/25, Clear River (Roseau, Philip) 9. Total 9 Chrysops mitis June-4/23 (Ramsey, Knight) 9; 9/16, Minneapolis (Hennepin) '9; 12/21 (Hennepin, Hoffmann) 9; June-July, 1921, Itasca Park (Clear- water, Person) 69. Total 92 16/12, St. Anthony Park (Ramsey) 4?; 24/21, Itasca Park (Clear- water, Person) 29; 28/21, Lake Itasca (Clearwater) 9; 28/30, Itasca Park (Clearwater, Dawson) 39. Total 79 July—I/21, Itasca Park (Clearwater, Person) 29; 3-5/24, International Falls (Koochiching, Philip) c3', 129. Total 149 17/12 (St. Louis) 9. Total 9 August-27/15, Duluth (St. Louis) 9. Total Chrysops moechus May-30/22, Battle Creek (Ramsey, Hertig) 9. Total 9 June-16/22, Mora (Kanabec, Hoffman) di; 24/18 (Olmsted) 9. Total (3', 9 July-17-21/21, Princeton (Mille Lacs, Hoffman) 9. • Total Chrysops montanus Locality only—(Hennepin) 9. June-7/17, Excelsior (Hennepin) 9. Total 16/25, La Crescent (Houston, Philip) 9; 29/21 (Ramsey) 9; 30/22, Alexandria (Douglas, Hoffmann) 9. Total 39 July-5/29, Oak Forest (Ramsey, Wall) 39; 6/22, Nisswa (Crow Wing, Hoffmann) 9; 8/10 (Washington) 59; 9/25, Rice Creek (Anoka, Philip) 219; 10/29, Rice Plantation (Ramsey, Stehr) 14/25, Moore's Lake (Anoka, Philip) 29. Total 33? 17/no year (Ramsey) 9; 17/18, Crystal Lake (Hennepin, Riley) 9; 17/18, Crystal Lake (Hennepin) 59; 23/25, St. Paul (Ramsey, Kepperly) 9; 25/15 (Itasca) 9; 28/15, Lake Minnetonka (Hennepin) 29. Total ii? August-1/24 (Ramsey, Philip) 9; 5/24, Geneva (Freeborn, Philip) 2?; 11/24, Rice Creek (Anoka, Philip) cr. Total 39 17/25, Minneapolis (Hennepin, Kepperly) 9. Total September-3/20 (Ramsey, Knight) 9. Total 9 Chrysops lager June-28/26, Poplar Lake (Cook, Orr) 59. Total 59 July-3-5/24, International Falls (Koochiching, Philip) 39; 14/26, Poplar Lake (Cook, Orr) io?. Total 139 17/29, Poplar Lake (Cook, Orr) '09 ; 16/29, same, I?; 23/29, same, 4. Total 13? August-9/24, Rice Creek (Anoka, Philip) 59. Total 59 17/25, Glenwood Park (Hennepin, Kepperly) 9. Total 9 THE TABANIDAE OF MINNESOTA 5

ChrysoPs sackeni June-12/21, Lake Calhoun (Hennepin, Hoffman) 9; 14/25, Rice Creek (Anoka, Philip) 9. Total 29 20/14, University Farm (Ramsey) 9; 16/25, La Crescent (Houston, Philip) 49; 26/22, Sand Dunes (Anoka, Dawson) 9; 19/25, same (Philip) 159; 19/25, Tamarack Bog (Anoka, Philip) 49; 19/25, Coon Lake (same) 9; 21 and 28/25, Rice Creek (same) 9 and 19; 22/21, Lake Owasso (Ram- sey, Hoffmann) 9; 27/22 (Ramsey, Hertig) 9; 30/22, Sand Dunes (Anoka, Hertig) 29. Total 409 July-9/21, Minnehaha Creek (Hennepin, Hoffmann) 9; 106, St. Anthony Park (Ramsey) 9; 1025, Moore's Lake (Anoka, Philip) 179; 1/25, Dynamite Ponds (Ramsey, Philip) 9; 12/25, Moore's Lake (Anoka, Philip) 142, 189; 14/23 (same) 63', 1919; 14/25, Sand Dunes (same) 72, 9794; 13/22 (same, Hertig) 14/22 (same, Nichol) 49; 13/24, Moore's Lake (Anoka, Philip) d, io9. Total 292, 3419 17/25, Warroad (Roseau, Philip) 9; 17/25, Clear River (same) 29; 17/16, St. Anthony Park (Ramsey) 9; 21/15 (same) 29; 18/18 (same) 9; 21-28/15, Lake Minnetonka (Hennepin) 29; 21/22, Sand Dunes (Anoka, Mickel) 9; 28/23 (same, Hertig) 9; 23/23, Moore's Lake (Anoka, Philip) 49. Total 159 August-3/no year (Ramsey) 9; 1/24 (Ramsey, Philip) 9; 3/24, Moore's Lake (Anoka, Philip) 72, 539; 5/24, Geneva (Freeborn, Philip) 39; 7/24 (Ramsey, Philip) d, 39. Total 83', 619 26/24, Tamarack 'Bog (Hennepin, Philip) 9; 21/25, Moore's Lake (Anoka, Philip) 29. Total 39 Chrysops sequax August-5/24, Geneva (Freeborn, Philip) 69. Total 69 Chrysops striatus Indefinite-summer/19I9, Princeton (Mille Lacs, Haber) io9; (Hen- nepin) 39. Total 139 June-12/10 (Hennepin) 29; 14/25, Sand Dunes) Anoka, Philip) 4. Total 49 19 and 21/25, Sand Dunes (Anoka, Philip) 29; 21/25, Rice Creek (same) 9; 20/21 (Hennepin) 9; 22/25, Dynamite Ponds (Ramsey, Philip) 9; 24/21, St. Anthony Park (Ramsey, Hoffmann) 9. Total 69 July--6/no year, Excelsior (Hennepin) 9; 8/10 (Washington) 39; 9/11 (Washington) e, 9; 9/13, Minnehaha (Hennepin) 49; 9/25, Dynamite Ponds (Ramsey, Philip) 119; 13/24, Moore's Lake (Anoka, Philip) 9; 9/25 (same) 119; 14/23 (same) 279; 9/25, Rice Creek (same) 9; 14/25, Sand Dunes (same) 129; 14/22, same (Nichol) 9; io/16 (Hennepin) 9; 12/19 (Hennepin, Knight) 29; 10/21 (Ramsey, Knight) 29; 11/21, Bussey's Pond (Ramsey, Hoffmann) 9; 9/25, Rice St. (Ramsey, Philip) 39; 13/19, Hinkley (Pine, Haber) 9; 14/25, Sand Dunes (Anoka, Mickel and Person) 29; 14/22, Shakopee (Scott, Hoffmann) 9 same, at lights, 9; 16/16, Lake Calhoun (Hennepin) 9; 15/16, Lake Calhoun (Hennepin) 9. Total 899 16/16 (Hennepin) 9; 17/21, St. Anthony Park (Ramsey) 59; 17/18, Crystal Lake (Hennepin, Riley) 109; 17/22, Blakely (Scott, Hoffmann) 29; 18/23, St. Peter (Le Sueur, Hoffmann) 9; 21/15, St. Anthony Park (Ram- sey) 39; 18/25, Red Lake Falls (Red Lake, Philip) 9; 21/22, Sand Dunes 52 MINNESOTA TECHNICAL BULLETIN 80

(Anoka, Mickel) 9; 26/24, Tamarack Bog (Anoka, Philip) 759; 28/15, Lake Minnetonka (Hennepin) 79; 28/16, Forest Lake (Washington) 29/25, Fort Snelling (Ramsey, Philip) 39; same (Dawson) y. Total iii? August-3/20 (Ramsey, Knight) 4?; 5/24, Geneva (Freeborn, Philip) 189; 2/no year (Hennepin) y. Total 239 21/25, Moore's Lake (Anoka, Philip) 9. Total 9

Chrysops vittatus Indefinite-summer/19, Princeton (Mille Lacs) 29; Minnesota, 5?. Total 7? June-12/10 (Hennepin) 39; 14/25, Rice Creek (Anoka, Philip) 29. Total 59 19/25 (Anoka, Philip) 9; 19/25, Coon Creek (same) 9; 19/25, New Brighton (same) 29; 22/25, Dynamite Ponds (Ramsey, Philip) 4?; 29/10 (Hennepin) 9; 3022, Red Wing (Goodhue, Hertig) 21/25, Rice Creek (Anoka, Philip) 179. Total 279 July-9/25, Rice Creek (Anoka, Philip) ":?; 14/23, Moore's Lake (same) 9; 9/25, St. Paul (Ramsey, Philip) 29; 10/21 (Ramsey, Philip) y. • Total 6? 17/18, Crystal Lake (Hennepin, Riley) 249; 17 and 18/23 (Le Sueur, Hoffmann) 29; 19 to 27/22, St. Peter (same) 89; 21/11 (Washington) 9; 25/18, Highwood (Ramsey) 9; 25/18, Albert Lea (Freeborn) 9; 24/22, St. Peter (Le Sueur, Hertig) 29; 26/24, New Brighton (Anoka, Philip) 4?; 29/25, Fort Snelling (Ramsey, Philip) 29; 29/24, University Farm (same) 29; 21/25, Red Lake Falls (Red Lake, Philip) 29; 30/16, Lake City (Wa- basha) 30/18, Lake Independence (Washington) 29. Total 539 August-1/24 (Ramsey, Philip) 7?; 4/25, Taylor's Falls (Chisago, Kepperly) 29; 14/18, Glenwood Park (Hennepin) 29. Total '19 18/20, Elkhorn Creek (Carlton) 9. Total 9

Chrysops wieclemanni June-June, 1898 (Olmsted, Ainslie) d. Total d July-12/19 (Hennepin, Knight) 9. Total 9 August-9/24, Rice Creek (Anoka, Philip) 5Ys; 17/25, Glenwood Park (Hennepin, Kepperly) 9. Total 69 Haematopota americana Indefinite-Minnesota, 29. Total 29 June-16/24 (Roseau, Philip) 9. Total 9 July-1/24, Itasca Park (Clearwater, Person) 9. Total 9

Tabanus actaeon

August-2I and 22/22, St. Peter (Le Sueur, Holland) 29; 27/18, Butada Lake (county( ?), Huber) 9 29/15, St. Paul (Ramsey) (S. Total d, 39 September-1/22, St. Peter (Le Sueur, Dawson) g 5/22, same (Hoff- mann) 9. Total d, Tabanus a nis

June-I2 to 18/14 (Roseau) 209. Total 209 22/14, McGregor (Aitkin) 49; 25/15 (Itasca) 169; 28/21, Lake Itasca (Clearwater, Person) 9; 29/20, Thief River Falls (Pennington) 9. Total 229 THE TABANIDAE 017 MINNESOTA 53

July-I/21, Itasca (Person) 9; 3-5/24, International Falls (Koochi- ching, Philip) 7d', 89; 4/15 (Roseau) 9; 6/16, Moore's Lake (Anoka, Philip) 69; 8-1028 (Cook, Orr) 29; 05, Itasca Park (Clearwater, Daw- son) 49. Total 7g,229 17/25, Clear River (Roseau, Philip) 39; 18/25, Roseau (same) 9; 17/29, Poplar Lake (Cook, Orr) 9; 30/26 (Cook, Orr) 9. Total 69 August-8/28, Itasca (Clearwater, Orr) 9. Total 2

Tabanus atratus Indefinite-1914, North Branch (Chisago(?)) 9. Total June-14/25, Rice Creek (Anoka, Philip) 2d; 6/22, Montevideo (Chippewa, Olsen) 9. Total 2d', 9 21/25, Rice Creek (Anoka, Philip) 9; 25/25 (same) 9. Total 29 July-I2/22, Belle Plaine (Scott) 9. Total 9 20-30/22, St. Peter (Le Sueur, Hoffmann) 39; 22/21, St. Anthony Park (Ramsey, Knight) d'; 25/13, St. Anthony Park (Ramsey) 9; 30/23, Lake Minnetonka (Hennepin, Knight) 9. Total 59 August-4/22, St. Peter (Ramsey, Holland) d, 9- Total d', October-1921, Rochester (Olmsted) 9. - Total 9

Tabanus astutus June-25/15 (Itasca county) 9; June-July/21, Itasca (Clearwater, Per- son) 69. Total 79 July-4/15 (Roseau) 179; 3-5/24, International Falls (Koochiching, Philip) 1429; 5/22, Holbrook (county( ?), Hoffmann) 29; io/18, Rush Lake (St. Louis) ; 1-15/30, Itasca Park (Clearwater, Dawson) 69. Total 1689 17/25, Clear River (Roseau, Philip) 49; 19/25, Longworth (same) 9. Total 59 Tabanus bicolor Indefinite-(Hennepin) 9. June-i6/ii (Wright) 9. Total 29 18/28, St. Paul (Ramsey) d'; 22/23, St. Peter (Le Sueur, Dawson) cr, 9; 28/22, Lake Owasso (Ramsey, Hertig) ; 30/22, New Brighton (Anoka) 9. Total 3d1, July-5/22, Minneapolis (Hennepin, Hertig) 4d, 9. Total 4d, 16/21, Princeton (Mille Lacs, Hoffmann) 9; 17/25, Clear River (Roseau, Philip) 19S, io?; 23/23, Moore's Lake (Anoka, Philip) 9; 24 and 30/22, St. Peter (Le Sueur, Hoffmann) 9. Total 19d', 139 August-2/20 (Hennepin, Knight) 9; 7/24 (Ramsey, Philip) 4d, 29; 3/24; Moore's Lake (Anoka, Philip) d. Total 5d, 39 21/25, Moore's Lake (Anoka, Philip) Total cs

Tabanus cinctus July-I-15/30, Itasca Park (Clearwater, Dawson) 19; 6/24, Bemidji (Beltrami, Philip) 9; 27/29 (Cook, Orr) Total cr, 29

Tabanus dawsoni July-I-15/3o, Itasca Park (Clearwater, Dawson). Total 9 54 MINNESOTA TECHNICAL BULLETIN 80

Tabanus epistates Indefinite-June, July/21, Itasca (Clearwater,- Person) 9. Total 9 June-1/22, Sand- Dunes (Anoka, Mickel) 9; 12/14, Itasca (Clear- water) 29; 14/10, St. Anthony Park (Ramsey) d• Total d, 19/24, Hackensack (Cass, Philip) 39; 21/24, Vining (Otter Tail, Philip) 4?; 23/16, University Farm (Ramsey) 9; 25/15, Itasca (Clear- water) 9; 26/28, Itasca Park (Clearwater, Orr) 2?; 30/no year (Hen- nepin) d. Total d, iiy Ju1y-05, Itasca Park (Clearwater, Dawson) 179; 2/17, MinneapOlis (Hennepin) 9; 3-5/24, International Falls (Koochiching, Philip) 99; 4/15 (Roseau) 9; 6/24, Bemidji (Beltrami, Philip) 159. Total 43? 18/25, Salol (Roseau, Philip) 69'; 17/25, Clear River (same) 6'9; 18/25, Longworth and Warroad (same) 5 and 39; 18/25, Holt (Marshall, Philip) 9; 17/16, St. Anthony Park (Ramsey) 9; 17/18, Crystal Lake (Hennepin) 9; 20/24, University Farm (Ramsey, Philip) di; 22/22, St. Peter (Le Sueur, Hoffmann).?; 26/24, New Brighton (Anoka, Philip) 9. Total d, 25? August-3/24, Moore's Lake (Anoka, Philip) 79; 5/24, Geneva (Free- born, Philip) 9; 14, 25, Battle Lake (Otter Tail, Riley) 9. Total 9? Tabanus fulvicallus July-22/22, St. Peter (Le Sueur, Hoffmann) '9; Lake Minnetonka (Hennepin) Y. Total 2? Tabanus gracilipalpis

June-16/14 (Roseau) 9; 22/22, Clear River (Roseau, Gilmer) ?; 27/20, International Falls (Koochiching) 9. Total 3? Tabanus iliotus June-1/22, Sand Dunes (Anoka, Nichol) 9; 3-17/28, Itasca Park (Clearwater) 29; 10 and 14/25, Moore's Lake (Anoka, Philip) 15d, 49; 12/14, Itasca (Clearwater) 29; 14/10, St. Anthony Park (Ramsey) g. Total I6d, 19/25, Moore's Lake (Anoka, Philip) 6?; 19/24, Hackensack (Cass, Riley and Philip) 3?; 21/24, Vining (Otter Tail) 49; 23/16, University Farm (Ramsey) 9; 25/15, Itasca (Clearwater) 9; 30/no year (Hen- nepin) d. Total d, 15? July-05, Itaasca Park (Clearwater, Dawson) 19?; 3-5/24, Inter- national Falls (Koochiching, Philip) 99; 2/17, Minneapolis (Hennepin) 9; 6/24, Bemidji (Beltrami, Philip) 159; 9/25, Rice Creek (Anoka, Philip) otaC'.l 459 16/25, Warroad (Roseau, Philip) 4?; 17/25, Clear River (same) 3?; 18/25, Longworth, same) 9; 17/18, St. Anthony Park (Ramsey) ?; 17/18, Crystal Lake (Hennepin) y; 22/22, St. Peter (Le Sueur, Hoffmann) 9; 23/23, Moore's Lake (Anoka, Philip) ?; 26/24, New Brighton (same) 79; 20/24, University Farm (Ramsey, Philip) g Total d, 19? August-3/24, Moore's Lake (Anoka, Philip) 79; 5/24, Geneva (Free- born, Philip) 9. Total 8? 21/25, Moore's Lake (Anoka, Philip) y. Total 9 Tabanus lasiophthalinus Indefinite-summer, 1919, Mora (Kanabec, Haber) 29; June-July/21, Itasca (Clearwater, Person) 9; (Hennepin) 49; Minn. y. Total 8? THE TABANIDAE OF MINNESOTA 55

May-27/03, St. Anthony Park (Ramsey) 9; 27/22 (Hennepin, Nichol) d'; 30/21, St. Anthony Park (Ramsey, Knight) 9. • Total d, 29 June-12/14 (Roseau) 79, 2/24, University Farm (Ramsey, Philip) 9; 14/24 (same) 29; 5/91 (Hennepin) 29; 6/16, University Farm (Ramsey) 9; 10/14 (same) 9; 3/21, St. Anthony Park (Ramsey, Hoffmann) 39; 15/12, same (Babcock and Nelson) 9; 14/22, St. Paul (Ramsey, Hertig) 9; 7/25 (Ramsey, Philip) 9; 7/24, University Farm (same) d'; 7/25, Shakopee (Scott, Philip) 9; 7/25, Byron (Olmsted, Mickel) 9; 8/26, St. Paul (Ram- sey, Kepperly) 9; 12/26, St. Peter (Le Sueur, Kepperly) 9; 14/10 (Hen- nepin, Pro§sar) ; 13/98 (Olmsted) 29. Total 3S,269 16, 18/14 (Roseau) 149; 16/24, Rice Creek (Anoka, Philip) 9; 19/24, Onamia (Mille Lacs, Philip) 9; 21/24, Vining (Otter Tail, Riley and Philip) 49; 21/16, McGregor (Aitkin) 79; 21/22, Owatonna (Steele, Hertig) 9; 21/25, Rice Creek (Anoka, Philip) 29; 22/23, St. Peter (Le Sueur, Dawson) 39; 20 and 26/no year (Ramsey) 29; 17/16, University Farm (Ramsey) 39; 27/15, University Farm (Ramsey) 39; 30/no year (Hennepin) d'; 25/15 (Itasca County) 229. Total 639 July-3-5/24, International Falls (Koochiching, Philip) 126S, 569; i/To (Hennepin) d'; 1/15, Lake Minnetonka (Hennepin) 29; 1-15/30, Itasca Park (Clearwater, Dawson) 79; 4/15 (Roseau) 49; 6/24, Bemidji (Bel- trami, Philip) 179; 6 and 106, McGregor (Aitkin) 99; 6/16, Moore's Lake (Anoka) 29; 10/13, St. Anthony Park (Ramsey) 9. Total 127d,"89 26/24, New Brighton (Anoka, Philip) 29. Total 29 August-5/17, Minneapols (Hennepin) 9. Total 9 Tabanus imeola Indefinite-St. Anthony Park (Ramsey) 79; June (same) 9; July, Minnesota, 29. Total 10? June-10/14, University Farm (Ramsey) 29; 13/98 (Olmsted) 29; 12/14 (Roseau) 29. Total 69 17/25, La Crescent (Houston, Philip) 9; 20/26, St. Anthony Park (Ramsey) d'; 21/23, University Farm (Ramsey, Hoffmann) 9; 21/25, Rice Creek (Anoka, Philip) 29; 22/10 (Big Stone) 9; 22/23, St. Peter (Le Sueur, Hoffmann) 48; 27/22, same (Dawson) 59; 23/14, University Farm (Ramsey) ; 23/21, Tyler (Lincoln, Knight) 9; 27/12 (Otter Tail) d'; 27/21, Itasca Park (Clearwater, Person) 9; 29/30, Lake City (Wabasha, Lund) 9; 29/12, Foxhome (Roseau) 39; 30/23, Northfield (Rice) 9; 24/21, St. Anthony Park (Ramsey, Hoffmann) Total 3d, 229 July-2/24, University Farm (Ramsey, Philip) 9; 1/16, Lowry (Pope) 9; 1-13/21, Itasca Park (Clearwater) 9; 15/25, Salol (Roseau, Philip) 89; 4/16, Shakopee (Scott) 9; 5/22 Philbrook (Todd, Hoffmann) 39; 4/15 Roseau) 29; 5/07, Marshall (Lyon) 29; 6 and 9/12 (Wilkin) 39; 6/24, Greenbush (Roseau, Philip) 329; 8/27, Lake City (Wabasha, Mickel) d; 9/18, Starbuck (Pope) 39. Total 57? 16/16, Owatonna (Steele) 9; 17/14, St. Anthony Park (Ramsey) 9; 17/18, Crystal Lake (Hennepin) 9; 17-22/23 (Le Sueur, Kepperly) 89; 31/22, same (Holland) 9; 17/25, Clear River (Roseau, Philip) 229; 18/25, Badger (same) 249; same (Fox) 69; same (Warroad) 29; same (Strath- cona) 289; 18/25, Middle River (Marshall, Philip) 189; 21/14, University Farm (Ramsey) 9; 21/15 (same) 9; 22/29, Tamarack Bog (Anoka, Chap- man) 9; 30/20, Lamberton (Redwood, Jenson) 39; 30/18, Lake Independ- ence (Hennepin) 9. Total 1199 56 MINNESOTA TECHNICAL BULLETIN 80

August-7/24, University Farm (Ramsey, Brown) ?; 3/24, Moore's Lake (Anoka, Philip) ?; 6/15 (Wilkin) ?; 2/22, St. Peter (Le Sueur, Holland) 2?; 9/24, Rice Creek (Anoka, Philip) 9'. Total 6?

Tabanus longiglossus July-ii/i6, McGregor (Aitkin). Total ?

Tabanus metabolus Indefinite-(Olmsted, Ainslie) 29. Total 2? May-20/24, Battle Creek (Ramsey, Philip) ?; 20/22 (Hennepin, Hoff- mann) 91; 26/14, Frazee (Becker) ?; 30/28, Itasca (Clearwater, Orr)Tota?. l 4?

June-12/14 (Roseau) 3?; 14/24, University Farm (Ramsey, Philp) ?; 15/22, Penturen (Roseau) 9. Total 5? 21/24, Vining (Otter Tail, Philip) 2?; 19/24, Hackensack (Cass, Riley and Philip) i?; 21/16, McGregor (Aitkin) ?; 25/15 (Itasca County) 9?; 26/24 (Wadena, Carter) ?; 28/26, Poplar Lake (Cook, Orr) ?. Total 25? July-3-5/24, International Falls (Koochiching, Philip) 2?; 4/15 (Roseau) 8?; 6/24, Bemidji (Beltrami, Philip) ?; 11/16, MCGregor (Ait- kin) 3?. Total 14? Tabanus microcephalus June-21/21, Itasca Park (Clearwater, Person) ?. Total ? July-17/25, Clear River (Roseau, Philip) 9'. Total August-15/17, Aurora (St. Louis) ?;( ?) 20/20, Two Harbors (Lake, Knight) ?. Total?( ?) ? Tabanus nivoszcs -June-21/21, Itasca (Clearwater, Person) ?. Total ? July-I-15/30, Itasca Park (Clearwater, Dawson) ?; 2/1o, St. Anthony Park (Ramsey) d 6/24, Bemidji (Beltrami, Philip) C'• Total g, 2? 25/24 (Ramsey, Philip) ?; 27/28, St. Peter (Le Sueur, Hoffmann) 3?; 30/16, Lake Minnetonka (Hennepin) ?. Total 5? August-3/15, Deer River (Itasca) ?; 7/24 (Ramsey, Philip) ?. Total 2?

.Tabanus nudus May-30/28, Itasca Park (Clearwater, Orr) 2?. Total 2? June-Itasca Park (Clearwater, Orr) ?; 12/14 (Roseau) 7?. Total 8? 18/20, Lake Itasca (Clearwater, Graham) 9; 19/24, Hackensack (Cass, Philip) 8?; 21/15, McGregor (Aitkin) 6?; 25/15 (Itasca County) 49; 29/28, Itasca Park (Clearwater, Orr) 2cr. Total 2d, 19? July-3-5/24, International Falls (Koochiching, Philip) 133, 22?; 8/28, Poplar Lake (Cook, Orr) ?; 10/13, St. Anthony Park (Ramsey) 3?; 15/25, Salol (Roseau, Philip) ?. Total I33 27? August-25/27, Poplar Lake (Cook, Orr) ?. Total ?

Tabanus osburni July-18/25, Red Lake Falls (Red Lake, Philip) 5?. Total 5?

Tabanus orion July-17/99, Friesland (Pine) ?. Total ? THE TABANIDAE OF MINNESOTA 57

Tabanus reinwardtii

July-I/Io (Hennepin) d ; 14/22, St. Peter (Le Sueur, Hoffmann) 29. Total d, 29 2023, St. Peter (Le. Sueur, Kepperly) 9; 20/30 (same) 99. Total io9

Tabanus sagax Indefinite-Minnesota (Osten Sacken, 1876).

Tabanus scptentrionalis Indefinite-1914, North Branch (Chisago) 9, St. Anthony Park (Ram- sey 9; (Olmsted) 9; (Hennepin) 9; Mora (Kanabec) summer, 1915, 9. June-17/28, Itasca Park (Clearwater, Orr) 9; 22/21, same (Person) 9; 22/22, Clear River .(Roseau, Gilmer) 59; 25/15 (Itasca County) ; 25/no year (Pine) 9; 29/12, Foxhome (Wilkin) 39; 29/20, Clear River (Roseau) 39. Total '59 July-3-5/24, International Falls (Koochiching, Philip) 39; 4/15 (Roseau) 59; 6/16, Moore's Lake (Anoka) 9; 5/22, Philbrook (Todd, Hoff- mann) 79; 6/24, Bemidji (Beltrami, Philip) 9; 9/16, Lowry (Pope) 9; 15/25, Salol (Roseau, Philip) 79; 15/25, Badger (same) 39; 106, Mc- Gregor (Aitkin) 39. Total 319 16-30/22, St. Peter (Le Sueur, Hoffmann) 589; 22/23 (same) Hy; 19/23, same (Kepperly) 9; 16/16, Moose Lake (Cook) 39; 17/15, Forest Lake (Washington) 9; 17/22, Gray Cloud Island (Dakota) 9; 17/25, Clear River (Roseau, Philip) 449; 18/25, Fox (same) 39; 18/25, Warroad (same) 69; 18/25, Holt (Marshall, Philip) 9; 18/25, Middle River (same) 29; 19/15, Barnesville (Clay) 9; 18/25, Strathcona (Roseau, Philip) 29; 18/25, Badger (same) 9; 18/25, Longworth (same) 9; 18/25, Salol (same) 29; 25/18, Albert Lea (Freeborn) 9; 27/20, Armena (county( ?), Hendrickson) 9; 30/18, Lake Independence (Ramsey) 39. Total 1439 August-3/24, Pine City (Pine, Mickel) 9; 3/2, St. Peter (Le Sueur, Holland) 9; 5/24, Geneva (Freeborn, Philip) 9; 6/24, University Farm (Ramsey, Philip) 9; io/25, Deer River (Itasca) 9. Total 59 Tabanus st'ygius June-45/I (Houston) Total 9 23/23, Litchfield (Meeker, Brown) Total July-2/10, St. Anthony Park (Ramsey) 2d; ?/1916, Rushford (Fill- more 9. Total 2d, August-3/24, Moore's Lake (Anoka, Philip) 9- Total Tabanus trepidus June-18/14 (Roseau) 9; 18/2o, Lake Itasca (Clearwater, Graham) 9; 21/21, Itasca Park (Clearwater, Person) 9; 26/28, Itasca Park (Orr) 29. Total 59 July-I-15/3o, Itasca Park (Clearwater, Dawson) 49; 6/22, Nisswa (Crow Wing, Hoffmann) 9; 8/14, Clear River (Roseau) 9; 11/16, Mc- Gregor (Aitkin) 9; io/28 (Cook, Orr) 9; 14/26, Poplar Lake (Cook, Orr) 39. Total II9 17/25, Clear River (Roseau, Philip) 9; 24/28 (Cook, Orr) 9. Total 29 August-11/23, Itasca Park (Clearwater, Lakella) 9. Total 26/28 (Cook, Orr) 9. Total 58 MINNESOTA TECHNICAL BULLETIN 80

Tabanus trimaculatus Indefinite—June, Minn., y. June-14/25, Rice Creek (Anoka, Philip) d. Total d' 17/25, La Crescent (Houston, Philip) y; 21/22, Owatonna (Steele, Hertig) Y; 27/21, Minneapolis (Hennepin, Keene) Y; 21/25, Rice Creek (Anoka, Philip) g. Total 6? July-17/23 (Le Sueur) y. Total y August-20/15, La Crescent (Houston) 2?. Total 2?

Chart I. Seasonal Distribution of Minnesota Tabanidae Based on Actual Specimens Taken

May Tune July August Sept CHRYSOPSriA AESTUANS CHRYSOPS CALLIDUS

CHRTSOPS CARPANARIUS

CHRYSops CKLER

CHRYSOPS EXCI TANS

CHRYSOPS FRIGIDUS

CHRYSOPS FULVASTER

CHRYSOPS INDUS MN'M CHRYSOPS LUPUS

CHRYSOPS MU'S

CHRYSOPS MOIECHUS

CHRYSOPS MONTANUS V/7 CHRYSOPS NIGER

CHRYSOPS OBSOLITUS

CHRYSOPS SACKENI

CHRYSOPS SIQUAX

CHRYSOPS STRIATUS

CHRYSOPS VITTATUS W/A HAEMATOPOTA AMERICANA

TABUS ACTAEON

/SAF'HIS V A W.A THE TABANIDAE OF MINNESOTA 59

Tabanus trispilus Indefinite—(Hennepin) 61,9. July—I-15/30, Itasca Park (Clearwater, Dawson) 9; 2/24, University Farm (Ramsey, Mickel) 9; 15/24, same (Philip) 9. Total 39 20-30/22, St. Peter (Le Sueur, Hoffmann) 59; 22/15, University Farm (Ramsey) 9. Total 69 August-28/15, Hopkins (Hennepin) 9. Total

Chart I-Continued

May lune Tuly August Sept. TABANUS ASTUTUS 01111111111011M TABANUS BICOLOR \fl TABANUS CINCTUS

TABANUS ATRATUS (Oct TABANUS EPISTATES

TABANUS YULVICALLUS

TABANUS GRACILIPALPIS 1 TABANUS ILLOTUS

TABANUS LINEOLA MEV TABANUS METABOLUS

TABANUS MICROCEPHALUS

TABANUS NIVOSUS

• TABANUSr NUTXJS TABANUS OSBURNI

TABANUS REINWARDTII

TABANUS SEPTENTRIONALIS

TABANUS STYGIUS

TABANUS TP 'MS LI r TABANUS TRIMACULATUS TABANUS TRIS ILUS

TABANUS ZL70 60 MINNESOTA TECHNICAL BULLETIN 80

Tabanus

June-12-18/14 (Roseau) 6?; 12/22, Penturen (Roseau) 2?. Total 8? 21/16, McGregor (Aitkin) ?; 17/20, International Falls (Koochiching) 2?; 21/ and 24/21, Itasca Park (Clearwater, Person) 2?. Total 5? July-3-5/24, International Falls (Koochiching, Philip) 2,S, 2?; 4/15 (Roseau) 6?; 10/13, St. Anthony Park (Ramsey)7 3?. Total 2d', 8?

For purposes of comparison, these data have been presented graphi- cally in Chart I. The discontinuous nature of the data for certain of the species, due to the paucity of specimens or because of considerable gaps in the dates of collection, has prevented a more desirable graphic treatment such as the use of continuous, tapering bars for the seasonal occurrence of the various species. The diagrams therefore- represent only the actual numbers of adult specimens as listed above. As further collections accumulate, the gaps will undoubtedly be filled in because of the single-brooded development of probably all Minnesota species. The months of June, July, and August are spaced to accommodate a bar representing 50 specimens (both sexes) for each half of the months. The occurrence of more than 50 is indicated by proportionate solid bars so that a full solid bar represents zoo or more flies taken. Occurrence in earlier or later months is notably reduced; the spaces are therefore cut down, but the bars are in proportion to the rest of the chart. The operation of chance is especially evident in the diagrams for C. sackeni and C. vittatus, by which one might be led to suspect double broods involved because of the discontinuous nature of the bars representing occurrence during July. In the former this is based on totals of 23 (D and 343? taken in the first half of the month as compared with only 15? for the last half, while there is a sudden increase again to 8 iS and 61 ? in August. This spectacular difference is less significant, however, when one consults the detailed information. On July 14, in 1923 and 1925, the writer made large catches during a half day's collecting in each year. Either of these collections, if made 2 days later, would have filled out the bar for the latter part of July also. Again, the solid bar for early July occurrence of T. astutus gives the impression of swarm proportions during a very restricted period. One observes, however, that all except one catch of 142? are in reality rather small. Had this collection been made in a normal season a week earlier instead of in early July of a very late spring in Koochiching County, the bar could have been completely altered to indicate maximum abundance in late June. True seasonal distribution records for horseflies can be adequately obtained only by standard methods of collecting at stated intervals throughout the season in the same locality and prefer-

This seems a doubtful record, altho there are specimens with these labels. The species is a typically northern form and careful collecting has not revealed it in the vicinity of St. Paul or Minneapolis since the one collection listed. THE TABANIpAE OF MINNESOTA 6i

BOREAL Canadian Secs. 4,5. TRANSITION Plains . Sees. 1,2,3. Alleghanian Secs. 6,7. Carolinian Sec. 8.

r',a.4uLr a1P4V *;;itts

Fig. 3. Life Zones of Minnesota, with Reference to the Tabanidae ably over several seasons before one could hope to arrive at correct quantitative estimates of horsefly abundance. In Figure 3 is a diagram with faunal areas designated with Mer- riam's familiar terms but adapted according to certain floral and faunal characteristics so as to make a convenient form of reference in connection with a geographical tabulation of the Minnesota species of Tabanidae. The Canadian Zone of the Boreal Region enters the state in the coniferous forest belt of the northeast. The Transition zone of the Austral region, with its subtypes occupy the western and southern portions of Minnesota. The following distribution is based on the locality data for the species given above. 62 MINNESOTA TECHNICAL BULLETIN 80

Boreal Region Canadian Zone (Coniferous Forest Belt) Section 4 on map. Chrysops—aestuans, carbonarius, excitans, frigidus, indus, lupus, mitis, moechus, and montanus (southern edge), niger, sackeni, striatus (southern edge). Haematopota—ainericana. Tabanus--affinii, astutus, bicolor, cinctus, dawsoni, epistates, gracil- iPalpus, illotus, lasiophthalmus, lineola, longiglossus, metabolus, microcephalus, nivosus, nudus, septentrionalis, trepidus, trispilus, zonalis; Section 5 on map. Chrysops—excitans, mitis, niger, striatus southern edge). Tabanus—affins, astutus, atratus, cinctus, inetabolus, microcephalus, nudus, orlon, septentrionalis, trepiclus. Austral Region Trnsition Zone Prairie (Pseudo-campestrain) Section i (Southwestern tablelands). Chrysops—aestuans, fulvaster. Tabanus—lineola. Section 2(West central). Chrysops—aestuans, carbonarius. Tabanus—atratus, epistates, lasiophthalmus, lineola, vietabolus, septentrionalis. Section 3 (Northwest). ChrysoPs—indus, striatus, vittatus. Tabanus--affinis, ceratus, osburni. Typical Alleghanian (Eastern type) Section 6. Chrysops—aestuans, excitans, indus, moechus, striatus, vittatus, wiedemanni. Tabanus—actaeon, a nis, atratus, bicolor, fulvicallus, illotus, lasiophthalmus, lineola, nivosus, reinvvardtii, septentrionalis, trimaculatus, trispilus. Section 7 (South central). Chrysops—aestuans, indus, striatus, vittatus. Tabanus—actaeon, affinis, atratus, bicolor, fulvicallus, illotus, lasiophthalmus, lineola, nivosus, reinwardtii, septentrionalis, trimaculatus, trispilus. Semi-Southern Type (Pseudo-Carolinian). Section 8 on map. Chrysops—aestuans, callidus, carbonarius, celer, frigidus, indus, moechus, montanus, sackeni, sequax, striatus, vittatus, wiedenzanni. Tabanus—actaeon, affinis, atratus, bicolor, epistates, illotus, lasiophthalmus, lineola, metabolus, nivosus, nudus (northern edge), septentrionalis, stygius, irimaculatus, trispilus.

It must be remembered that in the above table, as previously treated, only the data based on actual captures is represented. Section 1, for example, has yielded only three species of tabanids but many more will be found with adequate collecting in that region. THE TABANIDAE OF MINNESOTA 63

Some notable species are included in the Minnesota horsefly fauna. Chrysops celer, frigidus, and niger, and Tabanus astutus, cinctus, microcephalus, and orion are representative of a more eastern fauna probably finding the western limit of their distribution in Minnesota. On the other hand, C. fulvaster and T. osburni are two species that are very abundant in Montana but enter this state only in reduced numbers along- the western border, in the southwestern and northwestern sections respectively. T. gracilipalpus has previously been reported only from Alaska, while C. lupus has also been included in that fauna and seems sparsely scattered along the Rocky Mountains into Colorado. The writer has taken the latter infrequently in Montana and specimens have been received from Eric Hearle from Alberta and British Colum- bia. C. sequax has been known before only from Kansas and Arkansas.

Climate and Topography of Minnesota Minnesota extends from the northern boundary of Iowa some 400 miles northward to the farthest point north in the United States, viz., the "Northwest Angle," a point of land which is entirely separated from Minnesota proper by the Lake of the Woods. The greatest width east and west is 367 miles. Its topographical features have been intimately connected with heavy glacial activities. The surface features can scarcely be described as abrupt anywhere, the larger part of Minnesota having an altitude between 1,000 and 1,500 feet, gradually sloping up or down to approxi- mate extremes of between 600 to 2,200 feet. There are more than 7,000 lakes dotting approximately 7 per cent of the total area of the state and on the north and northeastern boun- daries are extensive bodies of water, the Lake of the Woods and Take Superior, for considerable distances. A peculiar type of swampy land with much open water is also found over expansive areas in the north, known locally as muskeg. These areas embrace deep deposits of peat and muck, and consist of large poorly "drained districts. There are also large sections of rock outcrops in the northeast which provide pockets of all sizes for the retention of water. Extensive tracts have been reclaimed by drainage and clearing operations, but, needless to say, considerable portions of this part of the state are sparsely settled and for them attempts at drainage are impractical. Rivers, creeks, and other types of running water also contribute to the variety of aquatic and semi-aquatic environments to be found all over the state. With this wealth of moist and wet habitats to draw upon, it is small wonder that the tabanid fauna of Minnesota is abundant in both species and numbers. 64 MINNESOTA TECHNICAL BULLETIN 80

Climate.—The climate of Minnesota is doubtless considerably affected by this large amount of surface moisture. On the whole the climate is classed as continental, meaning that the temperature extremes are generally greater and the humidity and rainfall usually less than for areas bordering on the oceans. The state lies in the path of a large proportion of the low-pressure areas that move across the United States in a southeasterly direction crossing this state on an average of about two a week. The changes in weather are therefore rapid. Temperature and humidity.—The average annual temperature for the state as computed to 1920 is 41.0° F. with extremes of 109 at Red Lake as a maximum, and —59° as minima at Leech Lake Dam and Pokegama Falls as local records. January and February are the coMest months, with mean temperatures for the state of 10.5 and 11.2°; while June, July, and August, the months of greatest fly abundance, present means of 64.7, 69.3, and 67.1° F., respectively. There is a mean yearly. range of io degrees between the isotherms in the south and the northeastern portions of the state, viz., 45 and 35° respectively. The average annual precipitation is 26.08 inches. June and July are the wettest months, with averages of 4.18 and 3.79 inches, respectively. Rainfall is about one-fourth to one-third greater along the eastern boundary than along the western. The average annual humidity is 83 per cent at 7 in the morning and 72 per cent at that hour in the afternoon with very moderate variation throughout the year. Sunshine is abundant, comparatively speaking. For further details of Minnesota climate, Bulletin "W" of the United States Weather Bureau is to be consulted. Environmental Resistance and Tabanid Population Environmental resistance has been employed by Chapman (1926) with particular reference to insects to designate the sum of the factors, both animate and physical, that operate to inhibit the unlimited increase of a particular species. A few references are available regarding the numbers of eggs laid by certain species of tabanids in individual masses, but nothing is known of the number of masses usually laid by any one female during a season, nor regarding the sex ratio of the ensuing generation. Captures of worn tabanids about,stock suggests the taking of more than one blood meal and consequently the probable development of more than one egg batch by certain individual females. Since conservative averages place the numbers of eggs in single masses of Chrysops and Tabanus at 200 and at 300 to 400, respectively; yet the various species appear to remain more or less constant over a period of years in a given locality, the pressure of inhibitive ,factors on this development capacity or "biotic potential" must be tremendous to maintain the balance characteristic of the species. THE TABANIDAE OF MINNESOTA 65

Our limited information does not indicate which of the various physical or biotic factors determine the appearance of such wide-spread species as T. lasiophthalmus and T. lincola in outbreak proportions in the north but in reduced numbers farther south. Certain of these factors, therefore, are briefly referred to below without attempt at exact evaluation of their importance.

Physical Factors Weather.—In consideration of the contents of the previous section, the most vulnerable points in the activities of horseflies appear to be at the time of sudden and extreme changes in temperatures during hibernation in the larval stage, and perhaps of severe storms during adult activities in the breeding season. In regard to the former, observations by the writer during the winter of 1924 on soil temperatures at various depths down to 6 feet at the margin of a pond near the agricultural college indicates a considerable buffering to sudden lower- ing of the air temperature by the frozen mixture in the upper layers of the soil. The calorific requirements of latent heat during freezing of the excess moisture in these wet situations play no small part in the tempering of extremes during the winter. Mail (1930), in a thoro study of winter soil temperatures to depths of 2 feet under field conditions, has stated "it is the water content of the soil which is probably one of the chief intrinsic factors which might affect temperature variations." One might expect, then, that semi-aquatic situations would be less subject to variations than terrestrial conditions in a field such as the one studied by Mail, except under stress of freezing temperatures in the absence of a snow cover. However, a comparison of temperature readings obtained under the former condition with data accumulated simultaneously by H. L. 'Sweetman (unpublished) in an open field (sandy subsoil) would indicate a general similarity in temperatures in spite of the fact that the writer's thermal elements were located successively in sand and gravel for a little over a foot, in a layer of black muck and organic matter to Y2 feet, and in a layer of greenish gray clay of fine texture to 3 feet, below all of which lay the water table in a mixture of compact black muck and sand. Comparison of readings on 3 days during February and March of 1924, between the pond margin (Philip) and the open field (Sweet- man) stations within /34 mile of each other is given in Table III. The apparatus employed was essentially similar to that described by Mail (193o). 66 MINNESOTA TECHNICAL BULLETIN 80

Table 3 Winter Soil Temperatures at Different Levels at a Pond Margin (A) and in an Open Field (B) in Degrees Centigrade

Air One and 1924 temper- Sur- Half One one-half Two Three Four Five Six ature face foot foot feet feet feet feet feet feet

Feb. 5(A).... -4 -4.5 -3.5 -2.5 -2.25 -1.25 -I.0 0 0 0 (B).... -5 -6.25 --6.o -5.0 -4.5 -3.5 -2.25 0 0 0 Feb. 22(A).... -9 -3.25 -3.25 -3.0 -2.4 -0.75 -0.25 -0.25 0 0 (B). . . -II -5.75 -4.75 -3.25 -3.0 -2.75 -145 0 0 Mar. 5(A).... -7 -6.0 -5.5 -5.25 -4.5 -4.0 -3.25 -2.5 -5.5 -0.5 (B). . . . -5 -6.75 -6.5 -5.5 -4.5 -3.5 -3.0 -2.0 0 0 Remarks on conditions: Feb. 5 (A) Snow drifted about a foot deep along bank. (B) Snow-4 in. Feb. 22(A) One-half inch compact icy layer. (B) Surface of ground exposed, icy. Mar. 5 (A) Surface of ground exposed-icy. (B) Same.

From this it appears likely that at least part of the time during hibernation the ground is frozen about the larvae. Considerable dig- ging during the late fall failed to reveal the location of larvae during hibernation, but it is doubtful if they would have penetrated below the water table (Station A) at 3 feet, yet on March 5 freezing had occurred at a depth of 6 feet. Larvae of 3 species of Chrysops and 2 of Tabanus were later collected near the surface of the unfrozen soil in this situation in April. It is also of interest to note that on October 31, 1930, the writer collected two nearly mature larvae of Chrysops aestuans still actively feeding, immediately below a half-inch layer of frozen muck along the water's edge of a permanent pond near Minne- apolis, indicating that the ice was not driving them in a rapid downward migration. The minimal thermal death points of tabanid larvae were not determined, but larvae of T. stygius showed no ill effects after revival from exposure in wet sand that had frozen solid in a jelly glass accidentally left overnight in front of a slightly open laboratory window during subzero weather outside. There was no way of check- ing the temperature on the window ledge at this time, but it was probably not much below freezing. In agreement with the conclusion of Mail with regard to terrestrial insect larvae, it is even more doubtful if many tabanid larvae are destroyed during hibernation. However, Stone (1930) says that "they cannot survive in frozen soil, at least if it is moist, as the writer, discovered when trying to imitate natural conditions." The condition of the larvae at the time of his observations is not kno-wn, but if they had been subjected to freezing without "hardening" (i.e. laboratory stock) it is probable on the basis of the work of Payne (1926) and Robinson (1927) that greater susceptibility would be exhibited than among larvae that had passed through a process of "fall hardening" under natural conditions. THE TABANIDAE OF MINNESOTA 67

In the winter, the tremendous forces involved in shearing ice along lake shores, and in the summer, drouth, and fire in the peat beds are conceivable factors which might cause local but unimportant mortality among larvae. Tabanid larvae are highly susceptible to drying, but most of their natural habitats apparently retain enough subsurface moisture, at least, to carry. the larvae through the dry period. Drainage, however, appears to be the most important artificial factor in reducing breeding by removing attractive places of oviposition for the females. Large sections of the muskeg country in the north and of certain extensive peat areas in the south have been drained, and reports by the local residents indicate that such operations have reduced the horsefly pest considerably. Here, again, statistical information is lacking. Webb and Wells (1924) have concluded their bulletin on the tabanids of the Antelope Valley, in California, with the remark that "It is firmly believed . . . that drainage will accomplish the ultimate control of the tabanid pest . .

Biotic Factors Parasites.—Interest in parasites of the Tabanidae is steadily increasing, as evidenced by numerous references in recent years deal- ing particularly with egg parasites. Only one attempt has been made to utilize tabanid parasites in the control of horseflies in the field and this was in connection with the following species, Phanurus emersoni. Parasites of the egg stage.—Phanunts entersoni was recovered from most Chrysops egg-masses collected at the "Dynamite Ponds" in a small woods about one and one-half miles north of the Agricultural College, St. Paul, and at Rice Creek, Anoka county. Two egg-masses of 241 and 296 eggs each produced 29 and 33 parasites, respectively. One female of this proctotrypid species was found in the act of ovipositing and was not disturbed in her explorations by removal of the leaf bearing the egg-mass to the laboratory. She was watched for nearly 20 minutes as she wandered over the mass tapping the eggs with her antennae and occasionally stopping to "sting" an egg. In spite of the fact that she had beep observed apparently in the act of ovipositing at least 12 times even after being brought to the laboratory, only 5 parasites emerged from this mass of 221 eggs. Parasitized eggs are usually readily identified after a time by their dark rotund appearance in contrast to the collapsed appearance of eggs that contain larvae about to hatch or that have hatched. A few larger parasites of this species were also reared from two egg-masses of Tabanus lasiophtalmus that were collected in the same vicinity. These, corresponding to the size of the tabanid eggs, were almost double the size of individuals reared from the Chrysops eggs above. 68 MINNESOTA TECHNICAL BULLETIN 80

Webb and Wells (1924), Cameron (1926), and Parman (1928) have reared this parasite from tabanid eggs and the latter author reports favorable results following dissemination of parasitized eggs of T. hyalinipen*nis in relatively uninfested areas in Texas. Trichogramina ininutzon.—This chalcid species was reared from many eggs of C. aestuans collected at the "Golf Club Ponds" in open country one mile north of, the Agricultural College. Parasitism was not very efficient, as only 4 to 24 per cent of the individual eggs were infested in i i masses brought into the laboratory and counted. Cameron was the first to report this species parasitizing tabanid eggs. Anaphoidea sp.—This distinctive little chalcid parasite with feath- ered wings was reared from two egg-masses of Chrysops aestuans also collected at the "Dynamite Ponds" July 24, 1926. It is apparently not so common as either of the preceding species as a local parasite of tabanid eggs. This is the first record of Mymarinae infesting the eggs of horseflies. Parasites of the larval stage—Ncmatodcs.—On several occasions mature larvae brought in from the field have been found attacked by a heavy infestation of nematodes after a period in confinement, most frequently at the time of attempted pupation. Marchand (1920) also has reported observations on nematodes infesting tabanid larvae. Phorostoma n. sp. Aldrich.—Several larvae of Tabanus trimaculatus, were collected along the margin of a woodland pond within the city limits of St. Paul on May 3, 1926. On May 17, one of these was noted to be collapsed at one end, and, on closer examination, another dipterous larva was observed just completing the evisceration of the tabanid. This larva left the skin of the host to pupate and on June 12 a tachinid fly emerged that was subsequently determined by Dr. Aldrich to be a new species. Another tachinid larva was found in the mature larva of T. lasiophthalinus collected in an ant hummock in a tamarack bog near New Brighton, Anoka county, May 15, 1926. This larva eviscerated its host soon after collection. It was removed from the tabanid skin for examination and died without pupating. This is the first record of an insect parasitizing horseflies in the larval stage. Parasite of the pupae—Diglochis (Trichoglenes). occidentalis Ashm.—Eleven pupae of Chrysops initis were taken by the writer along the shore of Lake Bemidji. Four of these were found to be parasitized with this chalcid, 7 to 12 parasites issuing from each. That polyem- bryony was not involved is fairly indicated by the emergence of both sexes in each instance. The emergence hole was near the head of each pupa. Larvae collected at the same time were not apparently parasitized, altho no dissections were made to confirm this point. THE TABANIDAE OF MINNESOTA 69

Cameron is the only other investigator reporting pupal parasites, one of which was a new species, Trichopria tabanivora Fonts; the other, D. occidentalis. Parasites of adult tabanids.—Mites have been noted on a number of species of both Chrysops and Tabanus. There is. no apparent inconvenience to the host. A nematode about 2 inches in length, probably Gordius, was taken from the abdomen of a fresh specimen of T. astutus at International Falls, July 4, 1924. The worm was discovered by the slight protrusion of one end of its body between the third and fourth abdominal segments ventrally on the host. Nicholls (1920) reported a chalcid parasite of tabanids in Tasmania, the larvae of which were found attached to the proboscis of the host. Heavy infestations caused the latter to become weak and sluggish.

Predators The writer has observed Bembix spinolae capturing female tabanids about stock near Clear River, Roseau County. Parker (1917) observed the majority of the provisions of two of three nests examined of that species to consist of both Chrysops ,and Tabanus. Stictia carolina and Bentbix primaestate have been observed to capture horseflies in Louisiana and California. The latter species occurs in the southern half of Minnesota but not abundantly. Robber-flies (Asilidae) have not yet been observed preying upon horseflies in Minnesota, but have been so reported in the literature on several occasions. As predators of both adult and immature stages, birds play a minor role. The records of the Federal Bureau of Biological Survey show a list of 61 species which occur in Minnesota as having Included Tab- anidae in their diet. The greatest inroads, according to their records, have been made in the larval stages by the shore birds, with -Wilson's snipe, the black-bellied plover, and the greater yellow-legs as the outstanding birds of the group in respect to numbers of records and numbers of specimens eaten. The stomach contents of one of the former, which is very common in Minnesota, revealed 25 tabanid larvae. The crested flycatcher is the one most frequently recorded as taking adult horseflies. but the shore birds are likely the most efficient of the bird predators of the Tabanidae.

Cannibalism Cannibalism is in active progress among the larvae of Tabanus within the first week after hatching. It is undoubtedly a very important factor in the ultimate reduction of their numbers. This must 70, MINNESOTA TECHNICAL BULLETIN 80

be especially true in the early spring when the larvae have just come out of hibernation and are concentrated along the margins of various bodies of water, altho certain species were found not to feed before pupation in the spring. It is the writer's belief that a greater reduction in the numbers of the immature stages of Minnesota Tabanus occurs through cannibalism among the larvae than is accounted for by all their parasites combined. Cannibalism has never been noted among mature larvae of Chrysops, altho certain species have been noted to attack bits of earthworm and fly maggots offered as food, and larvae of C. aestuans have been found late in the fall having fed upon chironomid larvae. Partial evisceration of second instar larvae was noted a very few times among young Chrysops fulz,aster, the eggs of which had been obtained from Rock County. But the failure of the larvae to develop and the reluctance on their part to feed indicated that this was not a normal procedure.

Diseases Very little is known concerning this phase of the subject. In 1924 the writer lost several young larvae of T. stygius showing a peculiar accumulation of various sized, flattened droplets of a dark brown oily looking substance just under the skin in various parts of the body. These larvae appeared to be otherwise normal and occasionally molted, but they gradually became lethargic and finally died. This has also been noted rarely in mature larvae' brought in from the field, but the condition has never been serious enough to prevent pupation and emer- .-ence of such individuals. A more prevalent malady occurred among dormant larvae during or just preceding hibernation. Some physiological disturbance, probably of an excretory nature, was first indicated by a peculiar oedema of the body. This was soon followed by a slow atrophy of the Malpighian tubules as observed through the larval cuticle, and by an apparent plugging of the anus with a dark, tar-like material. Attempts to remove this plug invariably resulted in injury to the larvae. In rare instances a. bacteria-like, flaccid disintegration occurred in both larvae and pupae. However, one could never be sure that the condition was not induced by mechanical injury in collecting or by failure of a few larvae to form perfect pupae.

Preventive and Protective Measures From the -standpoint of immediate injuriousness to stock, the importance of specific determination is not so apparent when the adults only are considered. On an animal, they are just so many horesflies, and treatments are devised in a general way regardless of species. THE TABANIDAE OF MINNESOTA 71

The importance of distributional and taxonomic treatment according to species is realized when we attempt to consider preventive measures, however, for the initial developmental studies that have been made have shown that few generalizations are applicable to the development of the group as a whole. Drainage, as pointed out in the previous section, will apparently accomplish the most toward relief from the horsefly scourge in the northern part of the state. Entire relief can not be hoped for by this means, however, as there will always be seepage and other sources of moisture available for considerable. breeding. We have also seen that certain species utilize moist soil, decaying logs, bog-moss, and other places of breeding removed from shore lines of open water, so that restriction of breeding is the most that can be expected by drainage methods that are compatible with improvement of the land for the purposes of farming. Most of the proprietary applications for repelling horseflies have proved unsatisfactory because of the short duration of effectiveness, together with liability to hair and skin injury. Local dopes, usually consisting of some mixture of grease, such as common axel grease, and kerosene, or some other coal-tar product, have come into use in various communities. These arc mostly impracticable because of the labor and expense involved, or due to their deleterious effect on the stock. Internally administered repellants have been tried in various places from time to time without success. Ochmann 191 ) recommended potassium tellurate for internal use. Not long ago large sales of a supposedly fly-repelling salt were reported from a number of states in the middle west. Experiments (Aicher et al. 1927 and Parman et al. 1928) have failed to lend any encouragement to the use of this type of repellant. The farmer who buys this high-priced salt is merely wasting his money as far as any observable relief from the flies is concerned. The most satisfactory external repellant in Minnesota is that made up after the formula recommended in Press Bulletin No. 65, Kansas State Agricultural College. For cattle, the following formula is given: Parts Pulverized resin 2 Soap shavings Water fr1/2 Kerosene Oil of tar Fish oil Water 3 The resin and soap are boiled in the half part of water until the resin is dissolved. The oil of tar, kerosene, and fish oil are then added with 72 MINNESOTA TECHNICAL BULLETIN 80 the rest of the water, and the mixture is stirred while it boils for 15 minutes. The oily emulsion, after cooling, is applied with a brush every day for 2 or 3 days; subsequent applications are made every 3 to 5 days as they are needed. This repellant has been tried by farmers in Minnesota who have found that the applications appear to last longer than any other dope tried, and no harmful effects result if care is used in application. • A mixture suitable for horses, because it can be sprayed on, is recommended in the same bulletin to consist of 2 quarts of crude fish oil, i pint of crude carbolic acid, i ounce of pennyroyal, 8 ounces of oil cif tar, and quarts of kerosene. Cory (1917) found that a 3 per cent emulsion of pine-tar cresote affords complete protection for one day and considerable relief' for 2 days from horn and stable flies. The repellant giving most satisfactory results against horseflies in Florida is reported by Tedder (1925) as consisting of powdered resin 2 pounds, fish oil 2 pints, oil of tar 2 pints, and kerosene 3 pints. Graybill (1914) summarized the formulas recommended previous to that year. In preliminary tests with bland oil repellants for house, stable, and horn flies, Freeborn, Regan, and Folger (1925) found .that when cows were exposed to heavy infestations of the flies, milk production dropped considerably more under spray "protection" than when unsprayed. Such experiments, while not concerned with taban.ds, point out the danger of adding "insult to injury" by creating unnatural and additional annoying conditions involved in the application of the repellant. A serious objection to the use of repellants is the difficulty of treat- ing stock quickly and thoroly, especially if considerable numbers of animals must be handled. Applications with a brush by hand become impractical, and even spraying is tedious, considering the usual im- patience of the animals and the frequent repetition of the performance as the repellant loses its potency. A force spray has been found of use in certain sections of the western United States and in South Africa for ticks and mange, the animals being driven single file along a narrow alley and exposed to the jets from both sides. Dipping vats might also be used to advantage on farms seeking relief of large herds. Such vats are utilized successfully in the West to combat wood ticks. Extreme caution would have to be exercised in the use of any particular liquid repellant, however, in the absence of information on injurious effects. The cost alone of several repellants by the vat-full would be prohibitive in many instances. Several factors may contribute to a decrease in production in a dairy herd. As the season advances, maturation of grasses occurs and the nutritive ratio changes; the hotter days of July also have some THE TABANIDAE OF MINNESOTA 73 deleterious effect. These and other natural causes will have to be considered before satisfactory recommendations can be made with regard to the use of repellants. Another 'method of protection has been advocated by Portchinsky, in Russia, called by him the "pool of death." Pools of water that are noted to be visited regularly by tabanids are surfaced with oil and the visitors trapped. Under conditions in northern Minnesota, however, where the water is abundant, frequently rather inaccessible, and even moving, this idea would prove of little value, except perhaps under conditions as noted at International Falls in 1924, when open- water was considerably reduced because of drouth. The use of nets or other protective coverings are the only feasible means of relief that can be used for horses that are being worked. Shelters for pasturing stock •appear to be almost essential for the adequate protection of badly harrassed animals, which can otherwise feed in the open only during the early morning and evening hours. These measures have been described in a previous section.

III. LITERATURE CITED Aicher, L. C., Lush, R. H., and Smith, R. C. 1927 A year's test of a so-called "fly salt." Jour. Econ. Ent. 20:593-602. Bequaert, J. and Davis, W. T. 1923 Tabanidae of Staten Island and Long Island, New York. Bull. Brook. Ent. Soc. 18:113-22. Bey, H. C. E. 1930 A monograph of Egyptian Diptera. Part III. Tabanidae. Mem. Soc. Roy. Ent. D'Egypte. 4: Fasc. I, pp. 1-114. Brimley, C. S. 1909 Notes on the life-histories of Tabanidae (Diptera). Ent. News 22:133. Brumpt, E. 1927 Precis de Parasitologie. 4th ed. Paris. 1452 PP. Cameron, A. E. 1918 Some blood-suck:lig flies of Saskatchewan. Agr. Gazette of Canada, Ottawa. 5556-61.

1926 Bionomics of the Tabanidae (Diptera) of the Canadian prairie. Bull. Ent. Res. 17:1-44. Connal, A. and Connal, S. L. M. 1922 The development of Loa loa (Guyot) in Chrysops silacca (Austen) and in Chrysops dimidiata (Van der Wulp). Trans. Roy. Soc. Trop. Med. and Hyg. 16:64-89. Cornwall, J. W. and Patten, WI S. 1914 Some observations on the salivary secretions of the commoner blood- sucking insects and ticks. Indian Jour. Med. Research V. 2:569-93. Cory, E. N. 1917 The protection of dairy cattle from flies. Jour. Econ. Ent. 10:111-13. 74 MINNESOTA TECHNICAL BULLETIN 80

Degeer, C. 1760 Bromsarnas ursprung, uptaeckt af Carl Degeer, Konigl, Vetenskaps academiens Handlinger for Ar 1760. 21:276-91. Cited by Marchand (1920). Ferguson, E. W. 1927 Presidential address. Proc. Linn. Soc. New South Wales. 31-28. Francis, E. and Mayne, B. 1921 Experimental transmission of tularaemia by flies of the species ChrysoPs discalis. Pub. Health Repts. 36:1738-46. Fraser, A. D. 1920 Notes on blood-sucking flies in north Russia during the summer of 1919. Bull. Ent. Res. 11195-98. Freeborn, S. B., Regan, W. N., and Folger, A. H. 1925 The relation of flies and fly sprays to milk production. Jour. Econ. Ent. i8:779-90. Froggatt, W. W. 1915 March flies. Dept. Agr., New S. Wales, Sci. Bull. No. 3. 1-18. Graybill, H. W. 1914 Repellants for protecting animals from the attacks of flies. U. S. Dept. Agr. Bur. Ent., Bull. 131, 26 pp. Hart, C. A. 1895 On the entomology of the Illinois River and adjacent waters. Bull. State Lab. Nat. Hist. 4:220-47. Hine, J. S. 1903 Tabanidae of Ohio. Papers Ohio State Acad. Sci. No. 5 :1-57.

1906 Habits and life histories of some flies of the family Tabanidae. U. S. Dept. Agr. Bur. Ent., Tech. Series 12, pt. 219-38.

1906a A preliminary report on the horseflies of Louisiana with a discussion of remedies and natural enemies. La. State Crop Pest Comm., Circ. No. 6, 43 PP.

1907 Second report upon the horseflies of Louisiana. La. Agr. Expt. Sta. Bull. 93:1-59. Howard, C. W. 1916 Miscellaneous notes on economic work, i6th Rept. State Ent. Minn. p. 66.

1917 Insect transmission of infectious anemia .of horses. Jour. Parasitol. 4:70-79. Isaac, •P. V. 1924-25 Papers on Indian Tabanidae. Nos. Ito VIII. Agricultural Research Inst., Pusa, India, Dept. Agr. Memoirs. Ent. Series, Calcutta. 8:53-62, 93-109; 9:21-28. Jegen, G. 1924 Die protozoane parasitian-fauna der Stechfliege Stomoxys calcitrans. Zool. Jahrb., Abt. Anat. 46:389-472. Jones, T. H. and Bradley, W. G. 1923 Observations on Tabanidae (horseflies) in Louisiana. Jour. Econ. Ent. 16:307-12. THE TABANIDAE OF MINNESOTA 75

1924 Further observations on Tabanidae (horseflies) in Louisiana. Jour. Econ. Ent. 17:45-50. King, H. H. 1911 Report of the entomological section of the Wellcome Tropical Research Laboratories. Fourth Rept., Khartoum. Knab, F. 1911 Ecdysis in the Diptera. Proc. Ent. Soc. Wash. 1332-42. Leiper, R. T. 1913 Report of the Helminthologist, London School of Tropical Medicine, for the Half-Year Ending April 30, 1913. Rept. to the Advisory Com- mittee of the Trop. Diseases Research Fund. (Abstract, Trop. Dis. Bull. 2:195). Lugger, Dr. 0. 1896 Insects injurious in 1896. Minn. Agr. Expt. Sta. Bull. 48 (Out of print).

1896 Gad-flies. Breeze-flies. (Tabanidae). 2nd Rept. State Ent. Minn. 166-170 (Contents same as above). Mail, G. A. 1930 Winter soil temperatures and their relation to subterranean insect survival. Jour. Agr. Res. 41:571-92. Malloch, J. R. 1917 A preliminary classification of Diptera, exclusive of Pupipara, based upon larval and pupal characters with keys to imagines in certain families. Bull. III. State Lab. Nat. Hist. 12161-407. Marchand, W. 1917 Notes on the early stages of Chrysops. Jour. New York Ent. Soc. 25:149-63.

1920 The early stages of Tabanidae (horseflies). Alonograph Rockefeller Inst. for Med. Research, No. 13:1-203. McAtee, W. L. 1911 Facts in the life history of Goniops chrysocoma. Proc. Ent. Soc. Wash. 13:21-29. McAtee, W. L. and Walton, W. R. 1918 District of Columbia Diptera: Tabanidae. Proc. Ent. Soc. Wash. 20:188-206. Mitzmain, M. B. 1913 The biology of Tabanus siriains Fabricius, the horsefly of the Philip- pines. The mechanical transmission of surra by Tabanus striatus Fabricius. Phil. Jour. Sci. Section B. 8:197-221, 223-29.

1914 Collected studies on the insect transmission of Trypanosoma cvansi; summary of experiments in the transmission of anthrax by biting flies. Treas. Dept., U. S. Pub. Health Serv., Hgy. Lab. Bull. 94:7-48. Morris, H. 1918 Blood-sucking insects as transmitters of anthrax or charbon. La. Agr. Expt. Sta. Bull. 163 :3-15. 76 s MINNESOTA TECHNICAL BULLETIN 80

Neave, S. A. 1915 The Tabanidae of southern Nyassaland, with notes on their life histories. Bull. Ent. Research 5:277-332. Nieschulz, C. and Huber, F. L. 1928 Some blackleg and related disease transmissions with Tabanidae. Dept. Landb., Mijo. in Handel Nederland. Indie Veeartsenigh Meded. No. 67, Pp. 24-27. Osburn, R. C. 1913 Tabanidae as inhabitants of the hydrophytic area, etc. Jour. N. Y. Ent. SOC. 21 :63-65. Paoli, G. 1907 Intorno all 'organo del Graber, nelle larvae di ditteri tabanidi. Redia, 4:247-58. Cited by Marchand (1920). Parman, D. C. 1928 Experimental d:ssemination of the tabanid egg parasite Phanurus emersoni Girault and biological notes on the species. U. S. Dept. of Agr. Circ. No. 18, 6 pp. Parman, D. C., Abbott, W. S., Culver, J. J., and Davidson, W. M. 1928 Ineffectiveness of internal medication of poultry for the control of external parasites, U. S. Dept. of Agr. Tech. Bull. 6o, 24 pp. Parker, J. B. 1917 A revision of the Bembecine wasps of America north of Mexico. Proc. U: S. Nat. Museum 52:1-155. Patton, W. S. and Cragg, F. W. 1913 Textbook of medical entomology. Christian Literature Society for India, London, Madras, and Calcutta. Patton, W. S. and Evans, A. M. 1929 Insects, ticks, mites, and venomous animals of medical and veterinary importance. H. R. Grubb, Ltd., Croydon, England. , Payne, N. M. 1926 Freezing and survival of insects at low temperatures. Quart. Rev. Biol. I :270-82. Philip, C. B. 1928 Methods of collecting and rearing the immature stages of Tabanidae (Diptera). Jour. Parasitology 14:243-53.

1930 Possibility of mechanical transmission by insects in experimental- yellow fever. Ann. Trop. Med. and Parasit. 24493-502. Riley, C. V. 1887 Poisonous insects. Ref. Handbook of the Medical Sciences 5:763. Robinson, Wm. 1927 Water binding capacity of colloids a definite factor in winter hardiness of insects. Jour. Econ. Ent. 20:80-88. Scott, J. W. 1920 Experimental transmission of swamp fever or infectious anemia by means of insects. Jour. Amer. Vet. Med. Assn. 56:448-54. Schwardt, H. H. and Hall, D. G. 1930 Preliminary studies on Arkansas horseflies. Univ. Ark. Agr. Expt. Sta. Bull. 256, 27 pp. Stammer, H. J. 1924 Die Larven der Tabaniden. Zeit. Morph. Oekol. Tiere, Berlin I:121-70. THE TABANIDAE OF MINNESOTA. 77

Stone, A. 1930 The bionomics of some Tabanidae (Diptera). Ann. Ent. Soc. Amer. 23:381-89. Tedder, G. E. 1925 Control of horseflies (Tabanidae). Fla. Sta. Rept. 1925. p. 95. Washburn, F. L. 1905 The Dipiera of Minnesota. loth Rept. State Ent. of Minn. Tabanidae, 76-79. Webb, J. L. and Wells, R. W. 1924 Horseflies: Biologies and relation to western agriculture. U. S. Dept. of Agr., Dept. Bull. 1218:1-36.

PART TWO IV. SYSTEMATIC TREATISE Taxonomy of Adults

There are 351 species of Tabanidae, representing 21 genera, described from America north of Panama. Of this number 3 genera and 47 species acn be ascribed definitely to the territory within the state of Minnesota. The species fall into genera as follows: Chrysops, 18 ; Haematopota, I; and Tabanus, 28. In addition to the above, the genera Si/vius and Bup/ex with one species each, are treated here on the strength of their occurence in adjacent states. Lugger (1896) originally listed 3 Tabanus and i Chrysops from the state. The specimen figured by him as Tabanus rcinwardtii -Wiede- mann, is evidently not that species, and probably represents Tabanus scptcntrionalis Loew, judging from both the figure and his remarks. The only other work giving a list of species froM Minnesota is that by Washburn (1905) in which he includes 7 Chrysops, II Tabanus, "Pangonia," and i Si/vius. Neither dates nor focal:ties are included for any of them. The specimens were determined by various spzcialists and, unfortunately, several were incorrectly identified as indicated by labelled specimens in the collection. This occurred with Chrysops univittatus 0., C. pi/aris Washburn (= C. hilaris Will.), C. sordidzts OS., Tabanus reinwardtii Wied., T. phacnops 0.S., and T centron Marten. T. giganteus Degeer, T. costalis Wied. and T. rhombicus 0.S., though included in the list, are not represented in the University collection from within the state, but as they occur in neighboring statos, they may have been taken in Minnesota by some of the earlier collectors. Neither specimens nor records were found for "Pangonia" and Si/vius. None of the members of the family are really small. • The body is without bristles and usually robust, flattened. They have a large head, sub-hemispherical with the eyes contiguous in the male, more flattened 78 MINNESOTA TECHNICAL BULLETIN 80

in front with the eyes separated in the female. The antennae are 7 to Pc) jointed with no style or arista ; the third segment is usually considerably enlarged and almost bare contrasting with the hairy basal segments. The palpi are two jointed. The wings are enclosed by the ambiant costal vein and the alulets are large. The legs are moderately stout, and the empodia are pulvilliform. There are usually seven visible segments in the abdomen, the eighth and following being modified to form the terminalia of the post abdomen. Metcalf, in his studies of the Syrphidae, and others conclude that the first abdominal segment in the Diptera has become fused into the thoracic mass so that the first apparent tergite is really No. 2. Young, Bromley, and others have not concurred in this numbering, however, in their morphological studies and for convenience in key characters the writer has numbered the abdominal segments in the order seen, i.e., No. 1, No. 2, and so on. One of the difficulties arising in the study of the Tabanidae is the limited number of males usually in a collection, and, in some cases, the uncertainty as to which species the ones present really belong. The 'males are often the ones bearing the better diagnostic characters of the two sexes, and it is fully realized that further study will tremendously augment the data hereafter presented. The characters used in the keys and the treatment of the species are mainly those already employed in the literature and are usually self- explanatory. It has been the aim to confine the discussion of specific characters to those of most significance in the identification of the species concerned, or in its separation from those with which it is likely to be confused in our fauna. The more obvious variations from the previous descriptions in the literature are also mentioned. It .will be noticed that the Comstock-Needham system of wing no- menclature has been employed. Its merits are too well krkown to need justification for its use in this treatise and for thus departing from the older terminlogy. Both Tillyard (1919) and Shannon and Bromley (1924) have proposed changes in the designation of certain veins in the above system, but the terminology has been retained. There appears to be some evidence in favor of these changes, covering as they do certain moot questions in the relation of media and cubitus veins, and in regard to the spur which occurs on vein R, near its source in the Tabanidae and certain other Brachycerous families. After some study the writer decided that he was not qualified, with the materials available and without going into pupal dissections, to concur in the changing of an established system. The Comstock-Needham system has therefore been retained intact in the ensuing systematic discussion in the interests of uniformity, and without any implication as to the merits of the studies of the above authors. It may be mentioned that Shannon and Bromley, in advocating the combination .of veins R3+4 THE TABANIDAE OF MINNESOTA 79

instead of R,„ have neglected to rename the cell involved, which would be R, instead of 123; the latter necessarily disappearing according to their explanation of vein combination. In those species of Tabanus with isolated brown clouds on the cross- veins, a cloud also occurs in the region of this spur and the bifurcation of R., and R5, which makes one suspicious that the sectoral cross-vein is involved here somewhere. The spur, when present, however, is longer in some species than one would feel probable for an unattached cross-vein, and it varies in length not• only between species and individuals of the same species, but even on the two wings of the same specimen.7 It can, therefore, only be used with reservation and as a supplemental taxonomic character. Length, where mentioned in the specific discussions, refers to that of the females unless otherwise mentioned, and is included- only in case of deviation from measurements as they have been given by previous workers.. Similarly, the pattern of the eyes in living or relaxed specimens is also occasionally referred to, as it was of considerable use during the study. Only the more important refercnces or synonomy have been listed under the citation of the original description. For locality and dates of the specimens examined under each species, the distributional tabulations should be referred to in a previous section. The keys included are adapted for use in connection with Min- nesota species. The unnumbered species in the keys have not been taken within the state, but are included because of the strong likelihood of their occurrence here.

KEY TO GENERA OF TABANIDAE FOUND OR PROBABLY OCCURRING IN MINNESOTA

1. Hind tibiae with strong spurs at the tip, subfamily Pangoniinae 2 Hind tibiae with small spines but without apical spurs, subfamily Tibaninae 4 2. Antennae composed of 10 segments, the third of which is only a little longer than those following Bitp/ex Antennae composed of only 7 segments, the third of which is much longer than any of those following 3 3. Second segment of the antennae about half as long as the first, wings with isolated spots and a rather large stigmal spot Si/vins Second segment of the antennae as long as or but little shorter than the first, wings with a dark, more or less connected picture Chrysops 4. Third segment of the antennae usually more or less compressed with a basal prominence dorsally; wings hyaline, spotted, or suffused but not mottled Tabanus Third segment of the antennae rounded, without a basal process; wings mottled Haemalopota

This spur is produced to a greater extent in T. Products from Montana than in any other species that has come to the writer's attention; the spur is bowed upward and forward almost to vein R2+3 in certain specimens. 8o MINNESOTA TECHNICAL BULLETIN 80

Genus CHRYSOPS 1803 Meig,en Illiger's Magazine The species of this cosmopolitan genus are the well known earflies or deerflies, comprising generally medium-sized flies. They are the smaller species of the horsefly family having, in most cases, a bright, variegated appearance, and the eyes in life have characteristic purple maculations on a brilliant and often irridescent greenish ground. The wings are also characteristically pictured with a prominent "cross band" across the middle; the apex of the wing beyond this cross-band may be either hyaline, or with an "apical spot." The latter may be confined to a narrow costal margination, or the infuscation may occupy more or most of the area between the cross-band and the apex of the wing. The hyaline area posterior to the apical spot, termed the "hyaline triangle," •varies accordingly. There is no basal process on the third antennal segment and spurs are present at the apices of the posterior tibiae. The arrangement of the wing picture is the most important specific character in the genus, and the outer half of this pattern often furnishes the best clue to the relation of sexes, in those species in which there is a total dissimilarity between the abdominal markings of the male and the female. Even in those species in which the sexes most closely resemble one another, the proximal half envolving cells R and 2M with the anal cells are usually more extensively infuscated in the male than in the female. The extent of the cross-band and apical spot, when present, seems quite constant. Daecke (1907) has figured the patterns of the wings of 33 species of Chrysops including most of the Minnesota forms. The abdominal markings are of considerable importance, but are variable within limits, according to the species and the sex. Marchand (1918) has analyzed the abdominal pattern of several species of Chrysops according to "their phylogenetic value." While he had no intention of making this a basis for classification, nevertheless his work gives a better understanding of some of the specific variations encountered. The eye pattern in living or relaxed specimens has been of considerable help in this study; the terminology for the eye pattern used in the specific discussions of Chrysops, is given by Daecke (1906). Additional observation in this regard have been recorded below. As in most taxonomic work, therefore, combinations or groups of characters rather than single features should be considered for proper determinations. The genus was recently monographed by Krober (1926), who groups the species under 3 subgenera; C. fulvaster is classed under Hetero- chrysops and the other Minnesota species are placed as Chrysops s. str. THE TABANIDAE OF MINNESOTA 81

As all the following species are treated in this monograph, it has been omitted in the specific references.

KEY TO THE SPECIES OF CHRYSOPS OCCURING OR LIKELY TO OCCUR IN MINNESOTA' 1. Apex of wing beyond the cross-band hyaline 2 Apex of wing infuscated at least along the costal margin (i.e., apical spot present) 2. Abdomen yellow on sides of at least the first 2 abdominal segments 3 Abdomen wholly dark 4 3. Yellow on sides extending ventrally to include the sternites ; wing picture dark I excitans Yellow on sides confined to tergites, seldom reaching the posterior margin of the second ; wing picture light brown, faded cuchtx 4- Face yellow in the middle II. lager Face wholly black, the pollinose stripes only, yellowish 5 5. Base of cell Cui of wing with a hyaline spot; smaller species 8-9 mm III. carbonarius Base of cell Cu, of wing infuscated ; generally larger species over 9 mm. 6 6. Female with conspicuous tufts of orange-yellow pile on sides of thorax; male with cross-band practically filling out cell M3 to the posterior margin; hyaline spots in apical portion of cells R and 2dM occuping entire width of both cells IV. celcr Female with lateral thoracic pile inconspicuous, pale; male with at most an in fuscated spur along vein M3, and therefore the cross-band separated from posterior margin; hyaline in cell 2dM separated from posterior margin by a spur usually reaching apex V. mills 7. First antennal segment distinctly enlarged; apical infuscation of wing joins cross-band along posterior margin, enclosing the rather opaque hyaline triangle VI. fit/vaster First antennal segment normal in size; hyaline triangle reaches posterior margin of wing 8 8. Face black with a median stripe of yellow pollen VII. frigidus Face at least yellowish in the middle outside pollinose stripe 9. Apical spot of wing very narrow, confined within vein R2,3 and crossing narrowly into cell R3 when that vein diverges toward the costal margin 10 Apical spot on wing widened posterior to vein R2+3, at most the hyaline triangle sometimes reaching or crossing that vein only narrowly next the cross-band 10. Second abdominal tergite with black triangles either side the convergent median spot; in the males, the black ustially reaches the anterior margin Of the segment leaving only a yellow spot laterally...VIII. aestuans Second abdominal tergite with at most only lateral extensions of the median spot along the posterior margin IX. callidus 1. Hyaline triangle of wing produced toward the costa crossing vein R2+39.... 12 Hyaline triangle of wing not produced beyond vein R.)+3

Unnumbered species have a geographic distribution which probably includes Minnesota, altho they are not yet known to have been taken in this state. Of species taken, the ma!es of C. ca-citans and C. scquax are unknown to the writer. An infrequent specimen of sequar may show only faintly subhyaline indications of the triangle across vein R2, but the species is unmistakable on the basis 'of the rather narrow, arcuate, hyaline triangle. 82 MINNESOTA TECHNICAL BULLETIN 80

12. Dorsum of abdomen black with a mid-dorsal yellow stripe attenuated posteriorly, rarely an abbreviated yellow dash on either side.. X. wiedeinanni Dorsum of abdomen otherwise marked 13 13. Second abdominal tergite with a transverse subquadrate black spot in the middle deeply emarginate posteriorly with the yellow border 14 Second abdominal segment with dark markings completely divided by yellow 15 14. Facial callosities and cheeks yellow fitrcatus Facial callosities outside sutures, and cheeks black XI. lupus 15. Dorsum of abdomen with 4 longitudinal black stripes its full length; cell R in wings of female infuscated- XII. sequax Dorsum of abdomen without lateral markings on the first two segments; cell R in wings of female hyaline lateralis (=hilaris) 16. Apical spot of wing invading cell R, 17 Apical spot of wings at most confined to cell R4 19 17. Hyaline triangle small, sharply confined to the apices of cells M, and 2dM2 XIII. nzoechus Hyaline triangle extending forward of vein M, altho cell R, may be somewhat clouded 18 18. First 2 abdominal segments with 2 black stripes univittatus First 2 abdominal segments with 4 black stripes (see striatus) 19. Dark markings of the second abdominal segment convergent and united anteriorly, inverted u-shaped, the median yellow triangle blunt or rounded at the apex 20 Dark markings of the second abdominal segment longitudinally divided, continuous with those of the rest of the dorsum to form 2 or more stripes; when occasionally convergent, the median triangle is acuminate at the apex 22 20. Apical spot of wing relatively narrow, reaching only into the apex of cell R4 XIV. sackeni Apical spot of wing broad, occupying at least the anterior half of cell R4• • 21 21. Black spots on third and fourth abdominal tergites 4 in number, the yellow intervals linear in the middle and linear or rounded laterally XV. inontanus Black spots of these tergites transverse, two in number, partially or completely divided by the median triangles XVI. indus 22. S'cutellum and thoracic stripes contrasting yellow XVII. vittatus Scutellum largely black or plumbeous, thoracic stripes greenish gray XVIII. striatus

Chrysops aestuans van der Wulp 1848 Chrysops inoerens Walker, List. 1:201. , 1867 Chrysops aestuans van der Wulp, Tijdsch, V. Ent. 10:135. 1875 Chrysops aestuans Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:378. 1903 Chrysops inoerens Hine, Papers Ohio State Acad. Sci. No. 5:40. 1905 Chrysops aestuans Washburn, ioth Rept. Ent. Minn. 79. 1923 Chrysops moerens Hine, Ohio Journal Sci. 23:205. 1926 Chrysops inoerens Cameron, Bull. Ent. Res. 17:23 (larvae).

The description of Tabanus inoerens by Fabricius (1794) undoubtedly places that species in the genus Chrysops, which makes Chrysops THE TABANIDAE OF MINNESOTA 83 inoerens Walk, a preoccupied name and reinstates C. aestuans van der Wulp as the correct name for the present species. Specimens examined.-120 females, 13 males, Minnesota; 4 females, Ohio; To females, South Dakota; i female, Nebraska; 5 females, Saskatchewan. Distinguishing characteristics.—Apical infuscation on wings confined to a very narrow costal margination; dark lateral triangles on posterior margin of second abdominal tergite. Variations and separation.—Length 7-I1 mm. This species is very near callidus and intergrades in the series of specimens in the University collection make them difficult to separate. The size of aestuans averages larger than callidus, but small and large specimens occur in both species. In studying some of the variations of females from Minnesota, Professor Hine has emphasized the narrower apical spot, which is lighter than the cross-band, and the greater separation of the cross-band from the posterior margin in aestuans, in addition to the lateral abdominal triangles on the second segment as compared with callidus. These triangles vary in size also. The eye pattern of the female has not been figured by Daecke (1906). The occipital border is contiguous with the eye margin, but the upper and lower spots frequently are not. The median spot is usually rather small but connected by a heavy arm to the arrowhead. The latter is elongate, frequently connected below to the border, and the shaft may or may not emerge with the other maculations above. In one female the shaft is entirely missing, altho the other -markings are heavy. Abundance.—C. aestuans is common over most of the southern part of Minnesota. Only a few females have been taken in the northern half of the state in spite of the prevalence of this species as far as the Canadian northwest. Chrysops callidus Osten Sacken 1875 Chrysops callidus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:379. 1886 Chrysops callidus Williston, Trans. Kan. Acad. Sci. 10:132. 1903 Chrysops callidus Hine, Papers Ohio St. Acad. Sci. 5:35. 1918 Chrysops callidus McAtee and Walton, Proc. Ent. Soc. Wash. 20:195. 1930 Chrysops callidus Stone, Ann. Ent. Soc. Amer. 23:274 (larvae). Specimens examined.-189 females, 6 males, Minnesota; i male, Ohio; i female, New York. Distinguishing characteristics.—The narrow apical spot of the wings and absence of lateral dark triangles on the second abdominal segment are distinctive. Variations and separation.—Length 7-10 mm. The size in callidus averages smaller than that found in aestuans. Variations occur in which the inverted black "V" on the second abdominal tergite is produced along the posterior margin but no definite black triangle is formed BULLETIN 80 84 MINNESOTA TECHNICAL

laterally similar to that found in aestuans. Townsend (1895) mentions spot, similar variations in this respect. The wing pattern has the apical and regular in outline and of about the same density as the cross-band, the latter approaches the posterior margin more closely than in aestuans. Abundance.—C. callidus has so far been taken only in the vicinity of Minneapolis and La Crescent, and is never found in the abundance is usually that aestuans is, altho their occurrence together in this vicinity noticed. Chrysops carbonarius. Walker 1848 Chrysops carbonarius Walker, List. 1:203. Hist. 2:375. 1875 Chrysops fugax Osten Sacken, Mem. Bost. Soc. Nat. 1904 Chrysops carbonarius Hine, Ohio,Nat. 5:220. Wash. 20197. 1918 Chrysops carbonarius McAtee and Walton, Proc. Ent. Soc. Specimens examined.-24 females, Minnesota; 6 females, Wiscon- sin; 27 females, 2 males, Montana; i female, Connecticut. presence of Distinguishing characteristics.—The lack of an apical spot and a hyaline lunule in the base of cell Cu2 identify carbonarius. is Variations and separation.—Length 6.5-9 mm. This species hyaline separated from initis solely by its smaller size and the variable easily spot in the base of cell Cu, (see discussion under mitis). It is spine distinguished in the larval stage, however, as there is no stagmatal and there are other differences. Abundance.—It. is much less common than its near relative initis con- but occurs along with it in the same localities and under the same parts ditions. Both seem to occur in greater abundance in the northern of the state. Chrysops ccicr Osten Sacken 1875 Chrysops crier Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:376. Acad. Sci. No. 5 :36. 1903 Chrysops Mel- Hine, Papers Ohio St. 1905 Chrysops celer Washburn, loth Rept. St. Ent. Minn. 79. 20:197. 1918 Chrysops ccicr McAtee and 'Walton, Proc. Ent. Soc. Wash. Specimens examined.-14 females, Minnesota; i female, New York; i female, Ohio; i female, Quebec. of Distinguishing characteristics.—The lack of an apical spot, the presence wing char- a conspicuous pleural tuft of orange-yellow pile on the female, and the acters given in the key for the male are distinctive. The writer collected i i females of this species along Rice Creek, Anoka County, north of Minneapolis, June 14 and 21, 1925. Previous to this celer was represented by a lone specimen from Olmsted County in 1894. The eye pattern agrees with Figure i of Daecke (1906) in most specimens, altho there is a tendency for the shaft to fade out at its junction with the arrowhead. THE TABANIDAE OF MINNESOTA 85

Chrysops cuchtx Whitney 1879 Chrysops cuclux Whitney, Can. Ent. 11:35. 1903 Chrysops cuclux Hine, Papers Ohio St. Acad. Sci. No. 5 :20. 1918 Chrysops cuclux McAtee and Walton, Proc. Ent. Soc. Wash. 20197. 1930 Chrysops cuclux Stone, Ann. Ent. Soc. Amer. 23280 (larvae). I have been unable to recognize this species in our collection. Sev- eral specimens were labelled Chrysops cuclux Whit. that proved to be C. excitaizs and C. mitis. Rine, in correspondence with C. W. Howard, identified some specimens of this species that have not been located, but the species has been included on the strength of these determinations. It is most likely to be confused with small specimens of excitans, but the slight extent of grayish red on the sides of the first 2 abdominal tergites only and average smaller size will identify cuclux. Rarely a specimen of C. mitis has a small reddish spot laterally situated and confined to the second tergite of the abdomen. The lateral spot in cuclux is larger and of a lighter color, however.

Chrysops excitans Walker 185o Chrysops cxcitans Walker, Dipt. Saund. 1:72. 1875 Chrysops excit'ans Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2373. 1904 Chrysops excitans Hine, Ohio Nat. 5:222. 1905 Chrysops sordidus Washburn, loth Rept. St. Ent. Minn. 79. 1926 Chrysops cxcitans Cameron (descr. of male and larvae), Bull Ent. Res. 17:19 and 22. Specimens examined.-126 females, Minnesota; i female, Mon- tana; i female New Hampshire; i female, British Columbia. Distinguishing characteristics.—C. cxcitans is distinguished by the lack of an apical spot on the wing and a bicolored abdomen in the female. Cameron (1926) states that the male is entirely dark with an "irregularly quadrate hyaline spot" in the wing. Variations.—Length 7.5-12.5 mm. The abdominal pattern of the female varies. There may be gradations between specimens with only indefinite an black spot in the shape of an inverted "V" on the anterior border of tergites 2-5 of the abdomen, and no deep black even on its extremities, and specimens with a black dorsal pattern with grayish yellow only on the sides of the first 2 segments and the triangle on the second segment indicated only by a grayish tinge (no indications of the gray posterior margins reported for C. sordidus 0. S. are present in the latter variations). The venter varies from a uniform yellowish with darker fifth and sixth segments to a black with yellow lateral triangles segments on 2-4. Two of nineteen small specimens, 7.5 mm. mm. to 8.5 with yellow lateral areas abruptly ceasing at the posterior margin of the second segment, were confirmed by Hine as cxcitans, agreeing with variations he fluids in Michigan specimens. 86 MINNESOTA TECHNICAL BULLETIN 80

In most of the latter the shaft of the arrowhead in the eye pattern join is obsolescent. In all others relaxed, the shaft reaches upward to the occipital margin. The upper and lower spots are separated from the margin in all. Three specimens labelled C. cuclux Whit. and 2 as C. sordidus 0. S. belong here. Abundance.—This species is most abundant in the central and northern part of the state, Anoka County being the farthest south it has been taken. One specimen, a female, was caught dipping at water near International Falls, July 3, 1924.

Chrysops frigidus Osten Sacken 2:384; 1875 Chrysops frigidus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 1903 Chrysops frigidus Hine, Papers Ohio St. Acad. Sci. No. 5:37. 1904 Chrysops frigidus Hine, Ohio Nat. 5:223. Specimens examined.-9 females, 2 males, Minnesota; i female, 2 males, Montana. Distinguishing characteristics.—C. frigidus is peculiar in having an apical spot on the wings and an entirely black ground color to the face. Variations.—The abdominal pattern of this species varies even more. than that of the preceding species. In some specimens the abdomen is almost wholly yellow, in others it is totally infuscated, the yellow showing only as a browning of the posterior margins of the segments, and with the sides of the first segment. The venter varies from a yellow slight infuscation to black with brown at the posterior borders of the sternites. The legs, also, may be almost entirely black or yellow with infuscated trochanters, knees, and tips of the\ tarsi. The specimens from the north are noticeably darker than those taken in Ramsey, Hennepin, and Washington Counties. The eye- pattern is very much reduced in the females; the spots are no small, separated from the margin and from one another. There is with shaft above the arrowhead. The occipital border is contiguous the margin. Abundance.—Nowhere abundant.

Chrysops fulvaster Osten Sacken of the Terr. 3:221. 1877 Chrysops fulvaster Osten Sacken, Bull. U. S. Geol. Surv. 1904 Chrysops fulvaster Hine, Ohio Nat. 5:223. 1926 Chrysops fulvaster Cameron, Bull. Ent. Res. 17:21. 1928 Heterochrysops fulvaster Krober, Deuts. ent. Z. 1928, 427. Specimens examined.-12 females, Minnesota; 14 males, 288 f e- males, Montana; I female, Wyoming; 8 females, 3 males, Nebraska; female, Utah; i female, Colorado; i female, New Mexico. in our Distinguishing characteristics.—This is the only species of Chrysops hyaline triangle of the fauna having incrassate first antennal segments and the THE TABANIDAE OF MINNESOTA 87

wings enclosed. The males are usually darker and smaller in general appearance than the females. The first antennal joint is unusually large in C. inoechus male but not the extent of that in fulvastcr when compared to the second joint. The hyaline triangle will settle any doubt. Variations.—The Rock County specimens are somewhat darker than the western forms, yellow triangles in the second segments taking the place of the mid-dorsal yellow stripes. The occipital border of the eye pattern in the female is contiguous with the margin and joins the upper spot, which is separated from the margin; the arrowhead and median spot are barely discontinuous; the shaft is indicated by a short prolongation above the arrowhead, and the lower spot is barely contiguous with the margin, the rounded corners indicating an attempt at separation. All the spots are rather large. Abundance.—Capture in the extreme southwest corner of the state extend the range of this species to the edge of our fauna. The meager data for collections in that vicinity do not indicate whether or not it is as abundant as it is in the prairies farther to the west.

Chrysops indus Osten Sacken 1875 Chrysops indus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:383. 1903 Chrysops indus Hine, Papers Ohio St. Acad. Sci. No. 5:38. 1930 Chrysops indus Stone, Ann. Ent. Soc. Amer. 23:282 (larvae). Specimens examined. -226 females, 22 males, Minnesota; 2 females, New York. Distinguishing characteristics.—The apical spot of the wings is large, broadly joined to the cross-band; the dark markings on the second abdominal tergite are inverted "U" shaped, and on the following tergites, transverse partially or completely divided by mid-dorsal yellow triangles. Variations.—Length 6.5-10 mm. A rather wide variation in length finds its extremes in specimens from International Falls. In 3 females, the hyaline triangle of the wing extends beyond the region of the .bifurcation of veins R, and R5, half way across cell 1(3. Males have the yellow posterior margins of abdominal tergites 3 and 4 expanding into small triangles, occasionally the anterior may almost and the posterior completely divide the black on those segments. The eye pattern is variable; but only a few specimens show the heavy maculations figured by Daecke (1906). Occasional females are observed with the upper and lower spots separated from the eye margin, and rarely there is so much reduction of all markings that the shaft has almost disappeared and there is no connection between the arrowhead and the small median spot. Separation.—The abdominal characters given in the key easily distinguish it from montanus and the wider apical spot in the wing from sackeni. 88 MINNESOTA TECHNICAL BULLETIN 80

Abundance.—This is a rather widespread species but is not usually taken in any great series anywhere, altho the writer captured 66 females on June 14, 1925, along Rice Creek, north of Minneapolis. Chrysops lupus Whitney 1904 Chrysops lupus Whitney, Can. Ent. 36205. 1904 Chrysops lupus Hine, Ohio Nat. 5:224. Specimens examined.-4 females, Minnesota; i female, Wyoming; I male, 12 females, Montana; 2 females, Alberta. Distinguishing characteristics.—This species is readily characterized by the the hyaline black facial callosities outside the sutures together with the extension of triangle of the wings across vein R2. The black spot on the second abdominal 2 segments. tergite is emarginate posteriorly, and there are 4 spots on the following Variations.—Length 9 mm. to 10.5 mm. The hyaline triangle of the wings extends across the second longitudinal vein as a subhyaline spot, not quite separating the apical spot from the cross-band. The anterior coxae of the largest specimen are only slightly ferruginous along the outer side; the anterior tibiae on the proximal fourth and the middle tarsi in all specimens are ferruginous. Otherwise they agree well with Whitney's description. Several Montana specimens have the median spots on the second and third abdominal tergites united anteriorly, and in the male the lateral pairs are reduced. Wings of the latter have cells R and 2nd M infuscated on ,the basal two-thirds. The maculations of the eye pattern are reduced in the Minnesota and specimens. The occipital border is contiguous with the margin extends well around below, the median spot may or may not connect in all with the arrowhead, and the shaft disappears about half way up upper but 6 specimens examined in which it stops just short of the maculations. The. upper and lower spots are separated from the eye margin. Separation.—Some of the darker females of montanus with a considerable infuscation in cell R might be confused here, but the difference in extent of the hyaline triangle on the wing, and the usual extension of the lateral abdominal marking onto the second tergite, in addition to the characters mentioned in the key will separate doubtful specimens of montanus. In addition the mid-dorsal black on the first segment of hipits narrows posteriorly from about the width of the scutellum connecting- with that on the second, whereas in montanus fol- this spot is emarginate posteriorly and separated from that on the lowing tergite. The abdominal markings of htpus are much heavier than those of inontanus. This is a rather surprising addition to the deerfly fauna, being reported heretofore from Colorado, Alberta, and Alaska. THE TABANIDAE OF MINNESOTA 89

Chrysops initis Osten Sacken 1875 Chrysops in/as Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:374. 1904 Chrysops mitis Hine, Ohio St. Nat. 5:224. 1926 Chrysops mitis Cameron, Bull. Ent. Res. 1722 (larvae).

Specimens examined.—im females, 12 males, Minnesota; female, Wyoming; 16 females, Montana; i female, Saskatchewan ; female, Alberta. Distinguishing characteristics.—The characters g:ven in the key will suffice to distinguish Chrysops mitis 0. S. Variations and separation.—Length 8.5-11.5 mm. This species, as a series, is robust and characteristic specimens are rather easily distinguished from the typically smaller, more slender specimens of C. carbonarius, but the variations of the two show such close intergradations that serious doubt had been cast on the reliability of the variable, basal spot in call Cui as a distinguishing character for the latter. Williston (1886) mentions the small size of a specimen of mitis as does also Hart (1895). Daecke (1907) observes the correspondence of the eye pattern and mentions that Whitney has "no faith in their separateness" ; Hine (1904) also declares a doubt. The intensity and extent of the wing picture varies in both; the infuscation in cell R of mitis may vary from four-fifths to barely half the length of the cell; the cross- band may reach the posterior margin, as figured by Daecke (1907), or it may be separated by almost a fourth the length' of cell M.,. The hyaline spot in the base of cell Cui in carbonarizts may be narrow or wide, the hyaline or subhyaline with intergrades. The pollinose stripes of the facial callosities and of the pleural pile vary from gray to yellowish; and a small reddish spot has been observed on. the sides of the second abdominal tergite in rare instances in mitis. • The middle tibiae in carbonarius often show a proximal lighter color that has not been noticed in mitis. One male, 7.5 mm., exhibits the appearance of carbonanus in its slighter build, but shows no character to separate it from the rest of the series of more robust males of mitis. The larva of mitis, however, differs radically from that of carbonarius, which has been described by Stone (1930). This proves their separateness. Abundance.—This species is widespread and common in the northern half of the state and one of the worst deerfly pests of people and stock in the north woods.

Chrysops mocchus Osten Sacken 1875 Chrysops moccluis Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:387. 1903 Chrysops mocchus Hine, Papers Ohio St. Acad. Sci. No. 5:39. 1918 ChrysoPs mocchus McAtee and Walton, Proc. Ent. Soc. Wash. 20:197. 1930 ChrysoPs mocchus Stone, Ann. Ent. Soc. Amer. 23:283 (larvae). 90 MINNESOTA TECHNICAL BULLETIN 80

Specimens examined.-3 females, i male, Minnesota, i female, West Virginia; i female, Maryland. Distinguishing characteristics.—Hyaline triangle of wings small, limited anteriorly by vein M,, the inner margin angling across the basal two-fifths of cell M, to the distal end of vein M3. Variations.—One specimen has the frontal callosity tinged with ferruginous on the lower border grading to a deep brown above. The lateral longitudinal lines are obsolescent on the second abdominal tergites of this specimen; the median lines of tergites 2 to 5 curve laterally on the posterior part of the segment and on segments 3 to 5 unite with the lateral lines. The abdominal markings are more nearly longitudinal on the other specimens. Male abdomen is entirely dark with just a trace of yellowish on the sides of the first to third abdominal segments. •Separation.—This species is most likely to be confused with univittatus, but the female of the latter has cell R hyaline while that of inoechus is infuscated. The body of the male in inoechus is dark, while that of univittatus is bicolored, very similar to the female. Abundance.—Mocchits has been taken only from the central and southeastern parts of the state. It probably finds the northwestern limit of its distribution in Minnesota.

Chrysops montanits Osten Sacken 1875 Chrysops montanus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:382. 1903 Chrysops montanus Hine, Papers Ohio St. Acad. Sci. No. 5 :40. 1918 Chrysops montanus McAtee and Walton, Proc. Ent. Soc. Wash. 20:197. 1930 Chrysops montanits Stone, Ann. Ent. Soc. Wash. 23:284 (larvae). Specimens examined.-59 females, 5 males, Minnesota. Distinguishing characteristics.—Apical spot of wings broad, occupying half of cell R4; dark markings on second abdominal tergite inverted "U" shaped, and may tend on the 2 following divided into 4 subequal spots the lateral of which to fade infrequently, especially in the male. Variations.--Length 8-10 mm. Variations occur in the extent of the hyaline triangle between the apical spot and the cross-band in montanus. Two specimens from Geneva show the extremes in this respect where a subhyaline spot reaches the costa across vein R2+3. Very infrequently the convergent dashes on the second abdominal segment are barely divided by a fine projection of the median yellow triangle. The eye pattern of the females figured by Daecke (1906) for this species was less frequently encountered than one in which the upper maculations were merged at the apex, the upper spots being contiguous to the frontal margin or not. The lower spot was frequently variable in this respect with the upper. Arrowhead infrequently detached from the median spot. THE TABANIDAE OF MINNESOTA

Separation.—C. ntontanus is near striatus especially in a few females in which cell R is infuscated for more than half its total area (this cell in one specimen measures 2.75 mm in length, only 0.83 mm., of which is hyaline). The apical spot fills out cell R, less extensively and vein Cu, is infuscated in montanus, however. The separation of heavily marked specimens from lupus is mentioned under that species. Abundance.—This deerfly has been taken quite widely in the state, but nowhere abundantly except once along Rice Creek, near Min- neapolis, when 21 females were taken about the person of the writer during two hours collecting on July 9, 1925.

Chrysops niger Macquart 1838 Chrysops lager Macquart, Dipt. Exot. 1:161. 1875 Chrysops lager Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:377. 1903 Chrysops lager Hine, Papers Ohio St. Acad. Sci. No. 5 :41. 1918 Chrysops niger McAtee and Walton, Proc. Ent. Soc. Wash. 20:197. 1930 Chrysops lager Stone, Ann. Ent. Soc. Amer. 23:285 (larvae). Specimens examined.--37 females, Minnesota; 3 females, Ohio; female, Indiana; i female, New Jersey; i female, Connecticut; female, New York. Except for the fact that three of the Minnesota specimens are 9 mm. in length, all agree closely with the descriptions. No males were available for study but the lack of the apical wing spot and the ferruginous face easily distinguish this species, which appears to be a common form in the northeastern part of the state. The eye pattern in all these specimens differs from those figured by Daecke (1906) for the females in that the occipital border is separated from the margin of the eye. Variations.—Length 7.5-10 mm. The abdominal pattern in the Minnesota specimens is quite variable. The legs are yellow, the front tibiae and tarsi distally, and the hind femora proximally, being infuscated.' In 3 specimens, the apical spot does not cross vein R2+3 for a short distance along this vein beyond the cross-band. Only 2 of the males show the longitudinal streak in the second M cell described by Hine. The eye pattern in a large series of females studied is somewhat variable. The occipital border is always contiguous with the eye margin and usually the upper and lower spots are also. The majority also have the arrowhead connected with the median spot and with the shaft, all the upper maculations merging at the apex. Variations occasionally occur in which the spots may be separated. either from the eye margin, or in the case of the median spot, from the arrowhead. The shaft may also, be reduced but has not been observed to become separated above as it does occasionally below. Rarely the lower bor- 92 MINNESOTA TECHNICAL BULLETIN 80 der may connect with the elongate arrowhead or even with the lower spot Separation.—Some specimens appear to be close to callidits but the wider apical spot and the usually yellow callosity with brown upper border in the female should easily distinguish sackeni. Abundance.—All Minnesota specimens have been taken in the neighborhood of Minneapolis and St. Paul, with the exception of 3 from Freeborn County and 3 from Roseau County. Its frequency here, however, indicates it to be common southward.

Chrysops sequax Williston 1886 Chrysops sequax Williston, Trans. Kan. Acad. Sci. 10133. 1904 Chrysops sequax Hine, Ohio Nat. 5:225. 1918 Chrysops sequax McAtee and Walton, Proc. Ent. Soc. Wash. 20:198.

Specimens excmined.-6 females, Minnesota; i female, Iowa; 2 females, Nebraska. Distinguishing characteristics.—Apical spot is large, almost separated from the cross-band by the crescentic hyaline triangle, which extends into cell R1. The 4 longitudinal lines of the abdomen extend its full length. Variations.—The cross-band of the wings extends across the distal half of cell Cu, into the apex of the first' anal cell and up along vein Cu2, as a lighter infuscation. The hyaline arcuation transcends vein R2+3 as a subhyaline spot. The legs in all but one are predominantly black. Otherwise all agree closely with Williston's description. The eye pattern of the female is separated from the margin, as shown b5r Daecke, but the arrowhead is connected neither above nor below with the occipital border, altho in one specimen it is continuous with the median spot. Occurrence.—All Minnesota specimens were caught in woods bordering Lake Geneva, Freeborn County, Aug. 6, 1924, by the writer. They will undoubtedly be found in other counties in the southern part of the state with more intensive search.

Chrysops striatus Osten Sacken 1859 Chrysops viLiatus Bellardi (nec Wiedemann), Sagg. Ditt. Mess. 1:74. 1875 Chrysops striatus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 22:391. 1903 Chrysops striatus Hine, Papers Ohio St. Acad. Sci. No. 5 :43. 1918 Chrysops striatus McAtee and Walton, Proc. Ent. Soc. Wash. 20:198. 1930 Chrysops striatus Stone, Ann. Ent. Soc. Amer. 23:287 (larvae). Specimens examined.-248 females, 4 males, Minnesota; 3 females, Wisconsin; i female, Marylanq ; I female, New Jersey. Distinguishing characteristics.—Apical spot rather large, jo:ned to the cross- band by at least the width of cell R, and usually R3. Abdomen with 4 longitudinal dark lines, subequal in most specimens. The sexes are very much alike except the greater infuscation in the proximal pattern of the wing of the male. THE TABANIDAE OF MINNESOTA 93

Variations.—Length 6-9.5 mm. This is an extremely variable species, especially as regards the abdominal pattern, which may consist of 4 longitudinal lines running the full length of the abdomen ; or the lateral lines may be more or less obsolescent, and the median ones so close together as to leave only a narrow yellow median line widening on the posterior margin of each tergite. In these specimens there is often an acuminate, narrow, yellow triangle formed by the convergence and union anteriorly, of the 2 median spots on the second tergite ; but these spots never diverge widely to form an inverted "U" on this segment as in montanus or indus. The thoracic stripes may be typically "greenish-gray," or may vary to a yellow little different from some vittatus. The frontal callosity varies from yellow to black, and there may be an infuscation along the sutures of the face. The apical spot may fill out entirely cell R, except a small hyaline spot in the region of the bifurcation of veins R, and (I- 5, in which case there is an infuscated prolongation running outwardly toward the margin in the cell J-Z, suggestive of univittatus. The maculations of the eye pattern of the female are typically separated from the margin as figured by Daecke (1906) but the upper portion of the occipital border may be contiguous in an occasional specimen. Two extremes in these variations occur in which the dark markings in one are very much reduced, the frontal, facial, and genal callosities are yellow and the thoracic stripes yellowish at least laterally, and in the other the whole insect is darkened, the cheeks and facial callosities as well as the frontal callosity black, and the abdominal markings united on the second segment. Intergrades provide no line of demarcation, even for subspecific treatment. As indicated by Hine (1903), variations also occur very suggestive of scquax, especially in specimens showing a lighter area just beyond the stigma in the wing picture, and an extension of the apical spot to vein R,. A specimen labelled hilaris, belonging here, is probably the one on which the C. pllaris in -Washburn's list (1905) is based. Abundance.—This is our most common deerfly in the southern half of the state, but it has not as vet been taken north of Mille Lacs County, except at Red Lake, in the west.

Chrysops unjvittatus Macquart chrysops univittatus Macquart, Dipt. Exot. Suppl. 5:36. 1875 Chrysops vittatus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:390. Chrysops univitta;us H:ne, Papers Oho State Acad. Sci. No. 5 :44. This species has not been taken from within the state but its wide and common occurrence in the East and South, coming up into Illinois, makes it a very likely member of our deerfly fauna along the Miss- issippi, at least in the southwestern corner of the state. 94 MINNESOTA TECHNICAL BULLETIN 80

Readily recognized on the basis of the extensive apical,spot, which most nearly approaches moechus, and of the two rather than four dorsal abdominal stripes.

Chrysops vittatus Wiedemann 1821 Chrysops vittatus Wiedemann, Dipt. Exot. I:106. 1875 Chrysops vittatus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:390. 1903 Chrysops vittatus Hine, Papers Ohio St. Acad. Sci. No. 5 :44. 1905 Chrysops vittatus Washburn, loth Rept. St. Ent. Minn. 79. 1918 Chrysops vittatus McAtee and Walton, Proc. Ent. Soc. Wash. 20:198. 1930 Chrysops vittatus Stone, Ann. Ent. Soc. Amer. 23288 (larvae). Specimens examined.—i Do females, Minnesota; 8 females, Wis- consin; 2 females, Massachusetts; 2 females, New York; 1 female, New Jersey; i female, Maryland; i female, New Hampshire ; i female, Louisiana; i male, Illinois. Distinguishing characteristics.—The yellow scutellum, together with the yellow and dark contrasting thoracic stripes, serve to identify this species. Sexes are rather easily assocated by these characters. Variations and separation.—Length 7.5-10 mm. The frontal callosity frequently has an infuscated upper margin suggestive of sackeni. There is often a smoky projection toward the margin in cell R5, a condition noted in many specimens of striatus also. It may be readily separated from the latter by the yellow scutellum, together with a greater infuscation in the second M cells. The yellow thoracic stripes are usually distinctive also. The variations in the eye pattern of the female have been well figured by Daecke (1906). Abundance.—This species has not been taken as far north as striatus but seems to be common along with it over the southern part of the state. Neither becomes abundant before July.

Chrysops wiedemanni Krober

1875 Chrysops obsoletus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 4393. 1903 Chrysops obsoldus Hine, Papers Ohio St. Acad. Sci. No. 5 :42. 1905 Chrysops obsoletus Washburn, loth Rept. St. Ent. Minn. 79. 1918 Chrysops obsoletus McAtee and Walton, Proc. Ent. Soc. Wash. 20:197. 1926 Chrysops zviedemanni Krober, Settiner Ent. Zeit, 87:211.

Specimens examined.-8 females, I male, Minnesota; 2 females, Louisiana. Distinguishing characteristics.—The characters given in the key adequately distinguish this outstanding species. Abundance.—It has not been taken farther north than the vicinity of Minneapolis, and seems not to be abundant in any locality., Five females were the most taken at one time by the writer at Rice Creek, near Minneapolis. THE TABANIDAE OF MINNESOTA 95

ChrysoPs. sackeni Hine 1903 Chrysops sackeni Hine, Papers Ohio St. Acad. Sci. No. 5 :42. .Specimens examined.-363 females, 28 males, Minnesota, female, Ohio; 2 females, New York; i female, Wikonsin. Distinguishing characteristics.—The apical spot is narrow but crosses vein R2+3 for its entire length beyond the cross-band. The frontal callosity in the female is usually yellow with a brown upper margin. The sexes are easily asso-- ciated by the width of the apical spot and the general conformation of the abdominal pattern. The Genus BUPLEX 1920 Austen Bull. Ent. Res. Buplex rasa (Loew.) 1869 Pangonia rasa Loew, Dept. Am. Sept. Indig., Berlin, Ent. Zeit. 13:5. 1875 Pangonia rasa Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:366. 1903 Pangonia rasa Hine, Papers Ohio St. Acad. Sci. No. 5 :45. 1918 Pangonia rasa McAtee and Walton, Proc. Ent. Soc. Wash. 20:191. 1920 Buplex rasa Bequaert, Psyche 31:33 (Osten Sacken wrongly desig. author). Specimens examined.—T male, New York. This species was orginally described from northern Wisconsin by Loew. Osten Sacken lists Illinois through Le Baron. We may, therefore, expect to find it in the southwestern corner of this state, at least along the Mississippi Valley. Washburn (1905) listed "Pangonia tranquilla 0.S.," but it is doubtful if it occurs this far west. Hine (1903, P. 9) calls attention to the special attraction flowers have for both sexes of rasa even when cattle are grazing near by.

The Genus SILVIUS 1820 Meigen Syst. Beschr. Europ. Zwei. Ins. Silvius quadrivittatus (Say) 1823 Chrysops quadrivittatus Say, Jour. Acad. Nat. Sci. Philad. 333. 1886 Silvius quadrivittatus Williston, Trans. Kan. Acad. Sci. 10:131. 1904 Silvius quadrivittatus Hine, Ohio Nat. 5229. 1905 Silvius quadrivittatus Washburn, loth Rept. State Ent. Minn. 79.

Specimens examined.—I8 females, Montana; 2 females, Nebras- ka; 2 females, Kansas; i female, South Dakota; i female, Texas; female, Arizona. A specimen is in the collection from Srnithville, South Dakota, which probably formed the basis on the strength of which Washburn (im) listed it with Minnesota species. It undoubtedly occurs within the limits of our fauna and may have been taken by some of the earlier collections. It is reported by Wehr (1922) as common over the entire state of Nebraska. One specimen examined . from Kansas has a most curious aberrant cross-vein in cell R., of the left wing only, 96 MINNESOTA TECHNICAL BULLETIN 80 connecting vein M, with R just in front of the .bifurcation of R, and IR.5. A dark cloud surrounds this unusual cross-vein.

The Genus HAEMATOPOTA 1803 Meigen Illicrer's Magazine Haematopota americana Osten Sacken 1875 Haematopota americana Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:395. 1886 Haematopota americana Williston, Trans. Kan. Acad. Sci. 10:135. 1904 Haematopota americana Hine, Ohio Nat. 5:231. Specimens examined.-4 females, Minnesota; 3 females, Montana; female, Saskatchewan. Distinguishing characteristics.—Hacinatopota americana is the only species of the genus occurring in our fauna, and is very readily recogn:zed by the pe- culiarly broad head, the black antennae with the first segment incrassate, and the mottled wings as if water-marked with wavy lines. ,A rather striking character on all those specimens examined, but not mentioned by Osten Sacken, is the pale color of the halteres in pronounced contrast against the dark body. There is only a faint indicat:on in americana of the infuscat:on, which occupies all but the apex of the knob in the specimen at hand of its European relative, H. pluvialis Meigan. Abundance.—This species is of infrequent occurrence in the northern parts of the state. Late in the afternoon of July 4, 1924, a specimen was observed resting at the water's edge of a roadside puddle at International Falls. • When disturbed, it darted to another portion of the bank, remaining so close to the mud and water that it was impossible to take it before it finally darted away: The writer observed this species attacking stock in Montana.

The Genus TABANUS 1761 Linne Fauna Suecica This, admittedly, is a very difficult genus for any one but. the specialist to deal with taxonomically, despite some very excellent work by such men as Osten Sacken, Williston, and Hine, in this country, not to mention foreign contributions. The genus is world-wide in its distribution ; the medium or large size coupled with the biting propensities of the females, has caused them To attract considerable attention wherever they occur abundantly. Some of the smaller members of Tabaniv in Minnesota have no greater length than certain of the deerflies, but they are always more robust in appearance and are not easily mistaken even by the laymen who has once made their acquaintance. The members of this genus are the ones of most consequence economically in Minnesota, as has been previously emphasized. The genus is characterized by the lack of apical spines on the posterior tibiae, and by a more or less apparent dorsal prominence at THE TABANIDAE OF MINNESOTA 97

the base of the compressed, third antenna' segment. In addition, the larger size usually serves to distinguish the species. The wings are generally hyaline, sometimes with isolated brownish patches or clouds in the regions of cross-veins, n-m, m-cu, m (see Fig. 4), and the bifurcation of the veins R4 and R5; or there may be a suffusion of brownish or blackish, either over the whole wing or margining the veins in the basal part. There is no dark wing picture comparable to that of Chrysops in any of our species, however, nor is there any approach to the peculiar mottling found on the wings of Haematopota americana. The most trustworthy characters for the identification of the species in the genus are found in the structures and appendages about the head. The shape and width of the third antennal segment, the second segment of the palpi, the front and its callosity, the pollinose or denuded subcallus, and the vestiture and color pattern (in relaxed or living specimens) of the eyes, all furnish means for the discrimination between the females. The relative size and distribution of the large and small facets, and, to a less extent than in the females, the shape of the antennae and palpi, serve the purpose in the males. The comparative size of the front tarsal claws proves to be a good diagnostic character in the males of some species. Size , within certain limits is useful, and coloration, though more mutable is nevertheless an important means of identification, especially in associating the males with their respective females. It must be remembered, however, that specimens of the same species may exhibit considerable variation in regard to length or *size of body and for that reason, as has been mentioned previously, length has been included in the specific discussions where it was found to be above or below that recorded in previous references. The subgenus Atylotzts proposed by Osten Sacken (1887) is represented by only one species in our fauna, T. bicolor \Vied. Sixteen species occurring in the state belong to the prevalently western and middle western subgenus Titer/op/ea-es, and no to the Tabanus proper, with glabrous eyes of predominantly eastern distribution. T. reinwardtii Wied and T. hirtioculatzts Macq. seem to warrant subgeneric ranking on account of their peculiar combination of pilose eyes un- accompanied by an ocelligerous tubercle, in the female. The presence of a piominent frontal callosity excludes them from A ty/ohts. Because the pile on the eyes is so short as to be easily overlooked, reinwardtii has been given a double reference in the key.

Explanations Regarding Key As has already been explained, unnumbered species are not known to have been taken in the state but are of likely occurrence. Because 913 MINNESOTA TECHNICAL BULLETIN 80 of the homogeneous character of this large genus, keys to its species will always present difficulties. The males, when present in a collection at all, are seldom represented by any series and are often difficult to associate with their respective females. Yet they frequently offer the best of taxonomic characters. They are usually darker and occasionally show some confusion of coloring.- when compared to the females, i.e., T. lineola Fabr. Despite the fact that few males were available, it is hoped that most of them may be identified with a little care in the use of the key and supplemental specific discussions. The pilosity, or bareness, of the eyes are sometimes very unsatisfactory characters even when supplemented with the presence or absence- of an ocelligerous tubercle in the female, as suggested by Osten Sacken (1887). Satisfactory keys have been made, for example, by Hine (19o7) and McAtee and Walton (1918) without employing these characters, but they are used here because it is thought that the advantage of keeping groups with affinities together outweighs that of a slightly simpler key necessitating a more artificial treatment. The degree of elevation and pilosity of the vertical triangle of the males is somewhat variable and valuable only as a supplemental character. However, in the males of the subgenus Therioplectes studied, the vertical triangle is usually a shiny dark brown without pile on top, and raised above the level of a line projected across the upper limit of the eyes when viewed from straight in front or in back of the head. In this subgenus it appears to be least raised in the males of T. illotus O.S. T. nivosus 0.S. males have the most prominent frontal triangle of those species observed with glabrous eyes. The third segment of the antennae in the males is usually more narrow and reduced but the excision and general form and color are like those of the females.

KEY TO THE SPECIES OF TABANUS OCCURRING OR LIKELY TO OCCUR IN MINNESOTA 1. Eyes pilose (in y short but distinct), no frontal callosity nor ocelligerous tubercle in y (subgenus Atylotus); body almost entirely dusty yellowish or grayish with yellow sides, wings weak, yellowish, unusually soft, feeble species in life, 12 mm. or under I bicolor Eyes pilose, ocelligerous tubercle usually present; or if eyes naked, without tubercle; callosity well-developed; body not chiefly yellowish; wings strong; robust species, seldom as small as 12 111r11 2 2. Eyes bare; no ocelligerous tubercle on vertex of female; verticle triangle usually pilose or pollinose in male, reduced at least to the level of the eyes, which show distinctly a region of enlarged facets making the head much larger than that of the female (Tabanus proper) 3 Eyes pilose; ocelligerous tubercle usually present in female; vertical triangle denuded shiny brown in male, raised above level of the eyes, which are quite uniformly faceted, leaving head subequal in size to that of female (subgenus Therioplectes) THE TABANIDAE. OF MINNESOTA 99

3. Wings with distinct brown clouds in region of cross-veins and bifurcation of veins R4 and 125 4 Wings without isolated clouds 7 4. Prevailing color of abdomen reddish brown sulcifrons Prevailing color of abdomen black or grayish 5 5. Abdomen uniformly black; wings brownish, clouds dark II. stygius Abdomen variegated; wings outside clouds hyaline 6 6: Abdomen black with a mid-dorsal row of contrasting whitish triangles on segments 3, 4, and 5 III. trimaculatus Abdomen grayish with 3 rows of spots dorsally (see reinwardtii) 7. Body and wings black IV. atratus Body at least bicolored or wings hyaline 8 8. Abdomen with a mid-dorsal stripe its full length 9 Abdominal markings not continuous along the median line, sometimes reduced or hardly apparent in some rubbed specimens 12 9. Costal cell yellowish io Costal cell hyaline V. lineola 10. Abdominal segments with rounded yellowish spots on either side VI. sagax Abdominal coloration on sides continuous ii ii. Abdomen uniformly light reddish brown laterally VII. dawsoni n. sp. Abdomen with lateral longitudinal lines costalis 12. Size large, over 17 mm. in length 14 Size smaller, II to 14 mm. in length 13 13. Body chiefly brown VIII. fulvicallus n. sp. Body dark with three rows of whitish contrasting markings on the abdomen IX. nivosus 14. Middle and front ,tibiae almost uniformly reddish brown; larger species, over 23 mm. X Orion Middle and usually the front tibiae distinctly whitish proximally, almost black distally; smaller species, 17 to 21 MITI XI. actaeon 15. (2) Abdomen with first 3 segments bright yellowish or orange, an inverted black triangle mid-dorsally, the remainder black XII. cinctus Abdomen not so marked 16 16. Abdomen black with a mid-dorsal row of conspicuous white triangles on the 2d, 3d, and usually the 4th segments XIII. trispi/us Abdomen not so marked 17 17. Abdomen black, a conspicuous yellowish or pale cross-band on the posterior margin of each segment XIV. zonalis Abdomen not so marked 18 18. Wings with distinct brown clouds in regions of cross veins and bifurcation of R4 and R5; faint only in smaller species under 14 mm. in length 19 Wings with veins sometimes margined with brown but without isolated clouds in above regions 22 19. Clouds on wings faint but usually distinct; species less than 14 mm 20 Clouds on wings dark, prominent; species usually over 14 mm. in length 21 20. Wings with 2d C cell of wings sub-hyaline; subcallus of female dull pollinose XVII. Motifs Wings with 2d C cell of wings clouded, brownish; subcallus of female denuded, shining XVIII. inetabolus 21. Antennae mostly reddish; abdomen broadly reddish on the sides, usually overcast with lighter oblique spots on each segment.... XV. /asiophthahnus 100 MINNESOTA TECHNICAL BULLETIN 80

Antennae mostly black; abdomen with 3 longitudinal rows of spots or triangles dorsally; no ocelligerous tubercle in female....XVI. reinwardtii 23 22. Abdomen with 3 longitudinal rows of distinct spots or triangles Abdomen broadly red or brownish on the sides, the dorsal interval consisting of a varying broad blackish band 28 23. Upper angle of 3d antenna! joint drawn out in a long process, falcate hirtioculaius Upper angle of 3d antennal joint not so produced 24 24. Whole body shining black; if there are reduced gray spots on the abdomen there is no red ground color beneath them; subcallus of female denuded XIX. osburni Whole body not black 25 25. Lateral abdominal spots rounded, usually golden pollinose over reddish ground color; variable species XX. scptcntriona/is Lateral- spots angular, grayish, sometimes with pinkish ground color 26 26. Second joint of palpi of female stout at base; length of body over 13 mm. 27 Second joint of palpi of female slender; length about 12 Intri.. XXI. astutus 27. Wings with bifurcation of veins R4 and R, without any vestige of a cloud; third joint of antennae slender, without basal prominence; subcallus of female pollinose XXII. microcephalus Wings with bifurcation of veins R4 and R, with faint cloud; 3d joint of antennae slightly excised forming a distinct basal prominence; subcallus of female denuded, shining rhombicus 28. Palpi of female deep ochraceous or dirty orange, gradually tapering and relatively elongate, more than 3% times as long as the widest point baso-laterally ; those of male darker, smoky, about twice as long as broad 31 Palpi of female pallid and swollen at base of 2d joint, strongly tapering and relatively short, less than 3 times as long as the lateral width; those of male creamy or pale yellowish, about 1'A times as long as broad 29 29. Subcallus of female denuded, shining; outer front tarsal claw of male over twice as long as inner XXIII. nuchts Subcallus of female dull, pollinose; front tarsal claws of male subequal... 30 30. Third antenna! joint broad, wholly reddish XXIV. cpistates Third antennal joint narrow, reddish only basally..... (see septcntriona/is) 31. Third antennal joint acutely excised dorsally; front of female narrow XXV. graci/ipa/pis Third antennal joint excised or not but the basal angle never more than rectangular; front of female moderately broad 32 32. Size large, 16.5-19 trim.; excision of 3d antennal joint distinct, subrectangular XXVI. affinis Size smaller, Jess than 16.5 mm.; 3d antennal joint slightly or not at all excised dorsally 33 33. Red on sides of abdomen extensive, black mid-dorsal interval narrow; third antennal segment broad, slightly excised with angular prominence; callosity of female subquadrate ; species 14-16 mm XXVII.. trepidus Red on sides of abdomen reduced, mid-dorsal black band broad; third antennal segment not at all excised, rounded dorsally; callosity of. female transverse; species 10-12 mm 34 THE TABANIDAE OF MINNESOTA loi

34. Proboscis and stylets long, subequal to height of head; palpi (female) a little over half that length, yellowish XXVIII. longiglossus, n. sp. Proboscis and stylets much shorter than head; palpi almost reaching tip of former, pale inimusculus

Tabanus actacon Osten Sacken 1876 Tabanus actaeon Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2443. • 1918 Tabanus actaeon McAtee and Walton, Proc. Ent. Soc. Wash. 20:20

Specimens examined.-4 females, 2 males, Minnesota. Distinguishing characteristics.—Large dark brownish species with unclouded, subhyaline wings, the front and middle tibiae are infuscated on the distal half at least. Osten Sacken does not mention the rather apparent rufus, appressed hairs on the dorsum of the thorax in the female. The males, measuring 175 mm., are essentially similar to the females. The front tibiae have less whitish proximally (almost absent in one specimen). The fringe of hairs on the hind tibiae is still predominantly light but is interspersed with more black hairs than that of the females and the rufus hairs are less apparent among the longer grayish vestiture of the top of the thorax. Variations.—Length 20-22 mm. Third segment of the antennae of T. actaeon is brownish red only at the extreme base, the black portion is dusted with a golden pollen to the tip. The pattern on the abdomen is variable according to the preservation of the insect. Typically, the incisures are whitish, the short whitish hairs at the base of the triangles being separated from those laterad by short black hairs on each side of the triangles. The wings mentioned by Osten Sacken with "a uniform pale brownish tinge" seem more hyaline as in T. ainericanus., much lighter than the "pale brown" noted for T. giganteus. Separation.—Rubbed specimens showing almost no trace of the triangles on the abdomen might be confused with giganteus, but the smaller size, more hyaline wings, distal infuscation on the legs and antennae will serve to distinguish actaeon. The difference of coarctation of the first posterior cell does not hold in all specimens of actacon compared to orion, but the coloration of the middle and front tibiae will serve to separate them. In the specimens studied the fringe of bristles along the outer margin of the posterior tibiae is black in orion and mostly light in actaeon and the cheeks of the males of the latter are pale grayish with darl yellow palpi while yellowish with dark red palpi in orion. Occurrence.—All but two specimens were taken near the fish hatchery at St. Peter. One male was taken by R. W. Dawson from a screen after dark attracted by the lights in the hatchery. The other male was labelled as T. superjumentarius Whit. and is the specimen, doubtless, responsible for the inclusion of that species in the Min- nesota list of Washburn, 1905. 102 MINNESOTA TECHNICAL BULLETIN 80

Tabanus affinis Kirby 1837 Tabanus affinis Kirby, Fauna Bor. Am. 4:313. 1876 Tabanus affinis Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:466. 1904 Tabanus affinis Hine, Ohio Nat. 5:234. 1921 Tabanis affinis McDunnough, Can. Ent. 53:140. Specimens examined.-64 females, 8 males, Minnesota; i female, Michigan; 2 females, Montana; 2 males, Massachusetts; 2 females, Alberta; 3 females, Manitoba. Tabanus affinis is the largest of a characteristic group of typically northern forms called after it the affinis group and treated especially by McDunnough (1921). The species concerned have the greater part of the first 4 abdominal segments reddish or brownish on the sides, separated by a varYingly broad, blackish dorsal band. Distinguishing characteristics.—This species is characterized by its large size, strong subrectangular excavation, and acute prominence 'of the third antenna! segment; in the female by its long, thin, rather blunt and deep-orange palpi. The tarsal claws and pulvilli of the male are subequal in length. The third joint in that sex is reddish only at the base, much more slender than in the female; the dorsal prominence is acute, the excision also subrectangular. Both joints of the palpi in those specimens before me are smoky, the second underlaid with deep ochraceous and but little more swdllen than the first joint. Red on the sides of abdomen is quite extensive, connected dorsally across incisures of the second and third segments. The mid-dorsal tufts of yellowish hairs are noticeable in well preserved specimens, especially on the first segment. The median golden pollinose triangles, noticeable in other males of the group, are not apparent here. Variations.—Length 16-19.5 mm. None of the females studied have the excised angle of the third antennal segment acute as mentioned by Hine (1923), tending rather to be more obtuse, when not rectangular, in the specimens examined. The dorsal prominence is acute, however. Separation.--The large males lack the elongate outside claw on the front tarsi, which is characteristic of the smaller males of nudus and, to a less extent, of epistates. The bands on the eyes in life are subequal, while those of nudus males examined have the blue intervals much reduced in comparison with the green bands. As revised by McDunnough, this species should be readily distinguished. Abundance.—Six females were taken near Minneapolis, the rest came from the northern part of the state, where they are less abundant than T. lasiophthalenus and T. nudus of the same group. At Inter- national Falls, I female was captured while dipping at a roadside puddle, together with a number of males. Tabanus astutus Osten Sacken 1876 Tabanus astueus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2471. 1918 Tabonus astutus McAtee and Walton, Proc. Ent. Soc. Wash. 20:202. Specimens examined.—174 females, Minnesota. THE TABANIDAE OF MINNESOTA 103

Distinguishing characteristics.—This horsefly is dark, having 3 rows of gray triangles on the dorsum of the abdomen. The palpi are rather long and of a dirty yellow color in the females. The third antennal joint is scarcely excavated. The male is not known to the writer. Variations and separation.—Length 11-14 mm. Occasional specimens have a reddish ground color showing through the lateral triangles on the second and third abdominal tergites. This, together with the more or less obliterated mid-dorsal row of triangles in rubbed specimens, leads to a superficial resemblance to illotus or metabolus. The denuded, shining subcallus in the latter species will distinguish it, and for differences between it and illotits, refer to the discussion of that species. Abundance.—T. astutus is probably an early species and was the most abundant at International Falls during the first warm weather they had had for the season. It was very persistent in its attack on stock, and some were continuously around the head of the collector, during visits to the edge of the forest.

Tabanus atratus Fabricius 1775 Tabanus atratus Fabricius, Syst. Ent. 789. 1876 Tabanus atratus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:454. 1896 Tabanus atratus Lugger, 2nd Rept. Ent. Minn. 168. 1903 Tabanus atratus Hine, Papers Ohio State Acad. Sci. No. 5 :48.- 1905 Tabanus atratus Washburn, loth Rept. Ent. Minn. 79. 1918 Tabanus atratus McAtee and Walton, Proc. Ent. Soc. Wash. 20:202. 1926 Tabanus atratus Bromley, Ann. Ent. Soc. Amer. 19:64-89. Specimens' examined. -13 females, 2 males, Minnesota; i female, South Dakota; 2 females, Wisconsin; i male and 2 females, Ohio; male, Texas; 2 males and i female, Florida. Distinguishing characteristics.—The entirely black or dark brownish body and wings in addition to its large size make afratus easily recognized. Abundance.—This well known species is never taken or even seen in any abundance in this state. It is of infrequent occurrence all summer, September being the only month between June and October that is not represented in the collection. The localities of capture have all been restricted to counties in the south central and southeastern parts of Minnesota as far north as Ramsey County, except for one record from Chippewa County and an indefinite record from North Branch, probably in Chisago County.

Tabanus bicolor Wiedemann 1821 Tabanus bicolor Wiedemann, Dipt. Exot. 1:96. 1876 Tabanus bicolor Osten Sacken, Mem. Bost. Soc. Nat. Hist, 2:460. 1876 Tabanus fulvcscens Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:461. 1900 Tabanus bicolor Hine, Can. Ent. 32247 (type of subgenus Atylotus). 1903 Tabanus bicolor Hine, Papers Ohio State Acad. Sci. No. 5 :48. 1918 Tabanus bicolor McAtee and Walton, Proc. Ent. Soc. Wash. 20:202. 104 MINNESOTA TECHNICAL BULLETIN 80

Specimens examined.-21 females, 31 males, Minnesota; i male, Illinois. Distinguishing characteristics.—This small, feeble species, which is entirely a flower visitor so far as we know, has a characteristic yellowish suffusion which gives both sexes a unique appearance in our fauna. Variations.—T. bicolor appears to be one of the most variable species of Tabanus in our fauna and is very hard to define. Characters ordinarily quite constant, here seem to present almost as many variations as there are specimens. Especially is this true in the shape and length of the third segment of the antennae, where the basal portion may be wide, prominent dorsally, the annuli short; or it may be of moderate width, with the annuli distinctly longer. The color of the eyes varies from light yellow to deep chocolate brown. Intergradations occur between typically yellowish specimens and an occasional "opaque black" suggestive of ohioensis. These darker variants may have only small yellow spots limited to the sides of the first abdominal segment, but they show no correlation with the variation in the shape of the antennal segments and the gradations leave no line of demarcation for any but the one species as far as can be found. Abundance.—It has been taken only in the central part of the state and in the far north near Warroad. About twice as many males of bicolor have been taken as females and both are usually collected by sweeping or from thistle blossoms.

Tabanus cinctus Fabricius 1794 Tabanus cinctus Fabricius, Ent. Syst. 4:366. 1876 Tabanus cinctus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:464. Specimens examined.-2 females, i male, Minnesota; i female, Massachusetts. Distinguishing characteristics.—The deep yellow sides to the contrasting black abdomen make this species unmistakable. As mentioned by Williston (1886), the color of the basal part of the abdomen is more nearly a deep yellow than the yellowish-red described by Osten Sacken. Occurrence.—The capture of the first specimen furnished a complete surprise. It was taken from a cow near Bemidji in 1924. The brilliant flash of yellow as it darted in to alight on the cow among other duller species in the vicinity, presaged the unusual. The male was taken in Cook County, in the northeastern corner of the state in 1929. Tabanus costalis Wiedemann 1828 Tabanus costalis Wiedemann, Auss. Zweifl. Ins. 1:173. 1876 Tabanus costalis Osten Sacken, Mem. Bost. Soc. Nat. Hist. 3450. 1903 Tabanus costalis Hine, Papers Ohio State Acad. Sci. No. 5 :50. 1905 Tabanus costalis Washburn, loth Rept. Ent. Minn. 79. 1918 Tabanus costalis McAtee and Walton, Proc. Ent. Soc. Wash. 20:202. THE TABANIDAE OF MINNESOTA 1135

Washburn (1905) included Tabanus costalis in his list but there are no specimens in the collection from Minnesota. Its wide distribution, including Nebraska and Illinois, make it of probable occurrence within the southern limits of our fauna. It is close to lincola, but it has the costal cell yellowish and only one cross-band on the eye in life.

Tabanus dawsoni n. sp. Type female.—Itasca Park, July 1-15, 1930. R. W. Dawson. Distinguishing characteristics.—Length 15 mm. Eyes naked; color pattern (relaxed) green with bluish overcast and 3 purple stripes, the median widest, attenuated and upcurved outwardly; upper and lower stripes linear, fading beyond the middle of the eye. Front moderately broad, slightly wider above, golden pollinose, with short black hairs on the vertex. No ocelligerous tubercle. Callus subquadrate, dark brown, occupying full width of front, merging broadly into the dark upper extension which broadens to nearly the width of the front above and stops just short of the vertex. Subcallus also golden pollinose, latter extending onto cheeks. Face light gray with whitish pile; sparce black hairs next the subcallus. Palpi pale yellowish, moderately short, pointed, incrassate basally; first joint covered with long whitish hairs, second with appressed black and white hairs intermixed. Antennae with first 3 segments bright orange, abruptly contrasting with the last 4 segments (annuli), which are black. Thorax grayish pollinose, dorsum with golden tinge and two faint abbreviated yellowish strips, anteriorly; sparce yellowish and black hairs, latter predominating on antealar tubercles. Pleurae and coxae with long whitish hairs. Legs light brown, darker on all tarsi, and proximally on front femora and distally on front tibiae.; covered with yellowish hairs; black hairs intermixed except on middle and hind femora. Wings with costal cell and veins yellow; no spur on vein R4. Halteres light brown. Abdomen reddish, darkening on the last 3 segments; a broad gray pollinose stripe mid-dorsally its full length, bordered by dark brown dashes on each segment. Appressed yellowish hairs in gray stripe, blackish on either side. Venter light red, slightly darker at the tip, covered with appressed yellow hairs. A sub- orbicular dark spot mesally, across the incisure of the first and second segments. In the collection of the University of Minnesota. Separation.—The uniform, mid-dorsal gray stripe on the red abdomen is distinctive and, together with the facial features, will easily distinguish it from lineola or costalis.

Tabanus epistates Osten Sacken 1876 Tabanus socius Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:467. 1876 Tabanus cpistates Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:555. 1903 Tabanus ePistatus Hine, Papers Ohio State Acad. Sci. No. 5 :5o. 1904 Tabanus epistatus Hine, Ohio Nat. 5:236. 1921 Tabanus epistates McDunnough, Can. Ent. 53:142. Specimens examined.-47 females, I male, Minnesota; i male, Manitoba. 1°6 MINNESOTA TECHNICAL BULLETIN 80

Distinguishing characteristics.—The almost entirely red antennae are characteristic of this species as compared with the other members of the affinis group in our fauna. The narrow, coarctate front, pollinose subcallus, moderately excised and broad third antennal segment, and pallid swollen palpi which taper strongly to a point distinguish the females. A male, reared from the same group of larvae with females, undoubtedly belongs here. The third antennal segment in this sex is not nearly as chunky as in the female and is excised much as in nuchts. Second joint of the palpi is pale yellowish, quite swollen as compared to the first joint. Outer claw and pulvillus about one-fourth longer than the inner front tarsal claws. The yellowish red of the abdomen is more extensive than in the female, the black on the second segment containing a golden pollinose triangle, that on the third tergite forming a small median spot; the red is joined across the incisures of both these segments. Variations.—Length 17-20.5 mm. One specimen is much smaller than the rest, being only 14 mm. in length. Separation.—The females are readily separated on the characters given above. The male measures 14.5 mm; the small size should readily distinguish it from the males of affinis, but it is not so satis- factorily separated from the males of nudits, for which see that species. Abundance.—The species has been taken in a great many localities but not often in very large series. It is notably more southern in its range than affinis, having been taken as far south as Le Sueur County. It also appears to occur normally later in the season than either affinis, nuclus, or /asiophthaintits, its near relatives. It was noticeably absent among a large series of the three latter species taken during the first warm weather of the 1924 season at International Falls.

Tabanus fulvicallus n. sp. Specimens examined.---1 female, Lake Minnetonka, Minn., July 30, 1916. (type) ; I female, St. Peter, Minn., Fish Hatchery, July 22, 1922, Wm. E. Hoffmann (paratype). Distinguishing characteristics.—Type female, length 12.5 mm. Eyes naked, antennae with first two segments dark red covered with black hairs; third segment red on the basal fourth, remainder black, excision very moderate, the prominence slight, width at base and length as 2 is to 3; terminal segments black. Subcallus yellowish pollinose; front slightly wider above, dark yellowish gray pollinose with black hairs, a narrow strip on each side of the callosity. The latter narrow yellowish brown sides rounded and tapering gradually into a light brownish, moderately broad line above which reaches half way to the vertex. No ocelli present. Face and cheeks pallid, no black hairs on these or on the first palpal joint. Second joint yellowish, moderately long, gradually tapering to a blunt point, coarse black hairs on the apical two thirds and short white hairs intermixed reaching to the base of the joint. Proboscis shorter than the length of the head. Thorax brownish clothed with short appressed blackish and gray hairs; antealar tubercle and the mesanepisternum with longer gray and black hairs intermixed ; the remainder of the pleurae with silky whitish hairs, especially dense THE TABANIDAE OF MINNESOTA 107

posteriorly. Anterior femora deep brown, median and hind pair yellowish, latter covered almost entirely with short white hairs. Black hairs on the inner face of the first pair. Tibiae yellowish, a little darker distally tarsi brownish. Wings including costal cell hyaline, stigma and veins clear brown vein R4 with a very short stump on one wing. Abdomen brown with faint indications of a central row of pale triangles and reduced light areas laterally on segments one, two, and three. Dorsum covered with short black hairs, except brief pallid fringes on the posterior margins medially and on the extreme lateral angles. Venter yellowish brown, darker toward the tip, the first 5 segments covered with short appressed whitish hairs, more black toward the tip. Paratype, 11.5 mm. Essentially similar but less well preserved. No indication of a stump on vein R4 of either wing. In the collection of the University of Minnesota. Separation.—Not to be confused with sagax, which has a yellowish costal cell, parallel sided front with dark almost quadrate callosity, and more definite abdominal markings. In Pay/this the front and callosity are more narrow. The body of the present species, while shorter, has a less slender, more compact, appearance and darker brown coloring than flavidus or longus. In addition, the latter species is distinguished by a pale yellowish costal cell, and dark square callosity occupying practically the entire width of the front. It was hoped that more specimens might appear during the investigation to enable more detailed study. This species is of a type very different from the usual species of horsefly found in Minnesota, having affinities with a type of fauna more southern in its distribution.

Tabanus gracilipalpis Hine 1923 Tabanus gracilipalpis Hine, Can. Ent. 55:143. Specimens examined.-3 females, Minnesota; i female, Alaska. Distinguishing characteristics.—The slender, gradually tapering palpi, the sharply excised antennae with acute basal angle, the pollinose subcallus, and the narrow front will distinguish the female of gracilipalpis from closely allied species of the aflinis group. The male is unknown. Variations.—One specimen from Roseau County is only 14.5 mm. in length, the front at the callus and the latter are narrower; and the extension above the callus is discontinuous and a mere streak as compared to the typical specimens in which the extension is almost half the width of the callus. The third antennal segment is also more acutely excised, the prominence with a considerable "overhang" as compared to the species of the "affinis" group in general. Identification of this specimen by Professor Hine.

Tabanus Motifs Osten Sacken 1876 Tabanus Motifs Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:469. 1904 Tabanus Motifs Hine, Ohio Nat. 5:238. 1922 Tabanus illotus McDonnough, Can. Ent. 54:238. MINNESOTA TECHNICAL BULLETIN 80

Specimens examined.-75 females, 17 males, Minnesota; 2 males, Montana; 6 females, Saskatchewan. Distinguishing characteristics.—The antennae are robust and compact in appearance for the small size of the flies and are black except for the reddish base of the third joint, which includes the subrectangular prominence. They are somewhat narrower in the male. Wings with the isolated clouds faint, the costal cell hyaline in the female, faintly yellowish in the male. Abdomen generally dull pollinose, with orange oblique dashes on a deeper red ground, most noticeable on segments 2 and 3. Female has gray pollinose subcallus. The outer front tarsal claws and pulvilli of the male are half again as long as the inner and the second palpal joint pale yellowish, noticeably swollen as compared to the first joint. Variations.—Length 11-14 mm. The extent of infuscation and excision of the third antennal segment varies slightly. The first and second segments also may be a little darker in some specimens. An adventitious character, in the form of a short stump, may be present at the base of vein R, on one or both wings. Otherwise all specimens agree well with Osten Sacken's description. Separation.—Rubbed females of astutus occasionally show a red ground color beneath the lateral spots on the second and third abdominal tergites which might be confused with illotits. The incrassate palpi, strongly tapering to a point, together with the faint brown clouds on the cross-veins and bifurcation of Ri and R, of the wing, will easily .distinguish illotits, however. The pollinose subcallus and dull abdominal pattern easily distinguish females from metabolus. The male of this species was identified by Professor Hine. It has the elongate claws on the outer side of the front tarsi nearly as long relatively as those found on males of nudits, which separate it from doubtful variations in the males of /asiophthahnus. Judging from McDunnough's description of the male of metabolus, there will be more difficulty in distinguishing it from that of illotus, as the latter has a more shiny appearance to the abdomen than observed on any of the females. Abundance.—T. illotus is a common and persistent pest of stock in the northern half of the state. It appears a little later in the spring and lasts longer in the summer than its near relative mctabolus.

Tabanus lasiophthalmus Macquart 1838 Tabanus lasiophthalmus Macquart, Dipt. Exot. 1:143. 1876 Tabanus asiophthalmus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:465. 1903 Tabanus lasiophthalmus Hine, Papers Ohio State Acad. Sci. No. 5:51. 1905 Tabanus lasiophthalmus Washburn, loth Rept. Ent. Minn. 79. , 1921 Tabanus lasiophthalmus McDunnough, Can. Ent. 53:142. Specimens examined.-499 females; 147 males, Minnesota; female, Wisconsin; i female, Florida ; 2 males, Maine; 2 females, Ohio; 4 females, Massachusetts. THE TABANIDAE OF MINNESOTA 109

Distinguishing characteristics.—The strong clouds on the wings on the cross-veins and bifurcation of veins R4 and R5, together with the prominent oblique yellowish dashes on the broad red sides of the abdomen render identification of both sexes usually easy. The denuded subcallus of the female is separated from the convex callosity above it by a rather deep transverse sulcus. The front tarsal claws of the male are subequal and the deep yellowish palpi are not strongly swollen. Variations.—Length 12.5-16 mm. This species is quite variable, a fact emphasized by study of the considerable series at hand. The infuscation of the antennae may be confined to the terminal segments or may extend onto the third, especially dorsally; the shape is constant, more slender in the male. The intensity of the clouds on the cross-veins also varies in some specimens; in 2 it is entirely lacking, a fact also observed by McDunnough (1921). The oblique yellowish area onthe abdomen may be either reduced to a mere trace in occasional specimens with a dorsal expansion of the reddish lateral areas, or they may be more prominent as the dorsal black stripe widens, reducing the lateral reddish areas. Separation.—The shape of the callosity and subcallus of the females will identify those variations approaching nudits, as noted under that species. For its separation from illotits,, see that reference. Abundance.—Its abundance and state-wide distribution make /asiophthahnits one of our worst horsefly pests of stock. Furthermore, it is one of the earliest species out in the spring and the last ones with us in the fall. The males were very abundant around a road-side puddle during early July at International Falls, 126 being taken ; on the other hand, only 7 of a total of 56 females were collected while dipping at this same puddle, the rest being captured around stock, or around the person of the collector. As those collections were made early in a late season, the indications are that the males appear in the greater abundance first. Tabanus lincola Fabricius 1794 Tabanus lincola Fabricius, Ent. .Syst. 4:369. 1876 Tabanus lincola Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:448. 1896 Tabanus lincola Lugger, 2nd Rept. Ent. Minn. 168. 1903 Tabanus lincola Hine, Papers Ohio State Acad. Sci. No. 5 :51. 1905 Tabanus lincola Washburn, loth Rept. Ent. Minn. 79. 1906 Tabanus lincola Hine, Ohio Nat.7:25. Specimens examined.-248 females, 6 males, Minnesota; i female, Massachusetts; 6 females, Kansas; 2 females, Texas; 18 females, Louisiana; 2 females, Florida; I female, British Columbia; i male, 2 females, Montana. Distinguishing characteristics.—The prominent mid-dorsal stripe, lighter in . the females, running the full length of the abdomen and the entirely hyaline wings lio MINNESOTA TECHNICAL BULLETIN 80

are quite characteristic. The reddish apex of the scutellum, and the peculiar outer and lower angulation of the eyes will usually help to identify doubtful cases from other species in our fauna. The eye colors in relaxed or living females are characteristic, with a central purple cross-band and an abbreviated one above it on a green ground, the whole enclosed by purple on the upper, outer, and lower margins. Variations.—Length 11.5-16 mm. The basal infuscation on the hind femora of lineola, mentioned by Hine (1906), rarely occurs in Minnesota specimens of either sex; the hind femora are usually heavily grayish pollinose, somewhat darker along the dorsal surface. The front tibiae seldom show as great a contrast proximally as do the southern specimens examined. In poorly preserved specimens, the mid-dorsal longitudinal stripe on the abdomen may be totally obliterated, leaving 2 lateral longitudinal brown patches, fading out usually on the third or fourth tergites. Abundance.—T. lincola is a very common "greenhead," well known over the entire state. Occasional specimens are still on the wing in August but the greatest abundance occurs in June and July.

Tabanits longiglossus n. sp. Type female: "McGregor, 7ji T/i 6"

Distinguishing characteristics.—Length 12 mm. Eyes minutely pilose ; color pattern (relaxed) 4 green stripes on purple ground, widest above. Front moderately broad very slightly divergent above; vertex pilose and pollinose, in front of which area is a moderate ocelligerous tubercle; front bare for its entire width about tubercle. Callosity and subcallus dark shining brown; three denuded brownish spurs above, separated from callus by pollinose area with short golden hairs. The middle of these spurs consists of a prominent ridge, all are attenuated above. Face, cheeks, and first palpal joint dark in consequence of being "greased," covered with creamy hairs. Second joints of palpi light brown, remarkably slender with short black and yellowish appressed hairs; a little more than half the length of proboscis. Latter subequal to head in length. Antennae chunky, short, reddish- brown, darkening apically on the annuli. Dorsal, basal prominence rounded, no excision. Thorax dark with yellowish and black pile intermixed. Antealar tubercles reddish with black and a few whitish hairs. Legs dark brown, yellowish on tibiae and distal halves of femora, mostly covered with black hairs. Outer row of bristles on hind tibiae black. Wings with costal and 1st M cells dilute yellowish, no spur on R4. Halteres dark brown, apex of knobs pale. Abdomen black with sides of segments i to 3 light reddish brown, the mid- dorsal black interval broad, covered with black appressed hairs, except pale on hind margins of segments. Venter in the middle and on lateral margins blackish, suffusions of reddish in between. Separation.—Very like mini/scut/is but the third segment of the antennae in the present species is broader, the subcallus denuded, the palpi much shorter in relation to the proboscis, and the bare areas above the frontal callosity more extensive. The lack of an angular prom- THE TABAIVIDAE OF MINNESOTA iii inence on the third antennal segment, the denuded subcallus and more transverse callus, longer stylets and proboscis, and more extensive black on the abdomen distinguish it from the larger trepidus and graciiipa/pis. The second joints of the palpi are also more slender in this species. This specimen was held several years in the hope that more would appear. It is so distinct, however, that it now seems advisable to describe it. It was examined by Professor Hine and labelled T. trepidus (?). Tabanus metabolus McDunnough 1905 Tabanus centron Washburn, loth Rept. Ent. Minn. 79. 1922 Tabanus metabolus McDunnough, Can. Ent. 54:239. Specimens examined.-55 females, Minnesota. Distinguishing characteristics.—The female of T. metabolus McD. is recognized by the yellow hair on the face and cheeks, the denuded subcallus and a_ general shiny body appearance with lateral reddish dashes laterally on the abdomen. There is a decided brownish tinge along the costal margin of the wings. One male is described by 'McDunnough (1922). In life, the eyes of the female are marked with 3 narrow green bands on a purple ground, and the upper, inner - corner is also greenish. This species was listed by Washburn (1905) under T. centron on the basis of determinations by the specialists before the species was known to be distinct. Variations and separation.—Length 10.5-14 mm. T. inetabolus is very similar to illotus but the denuded subcallus and the size and shape of the frontal callosity will separate the females. In well preserved specimens the shiny, almost "enameled" appearance of the black in the abdomen gives a suspicion of its presence amopg the duller specimens of illotus. The color of the subcallus and callosity varies from shiny black in most specimens to light brown in a few. The latter structures merge in a manner remindful of uudus, there being no deep transverse sulcus as seen in /asiophthaimu.s. Abundance.—As observed by McDunnough, inetabolus is one of the earliest species on the wing, but it seems not to be especially abundant in any particular locality in Minnesota.

Tabanus inicrocephalus Osten Sacken 1876 Tabanus microcephalus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2470. Specimens examined.-3 females, Minnesota. Distinguishing characteristics.—This dark species has unclouded Wings, slender antennae without a basal prominence, and 3 rows of light triangles on the abdomen underlaid with red laterally on the second or third segment in the specimens before me. Variations.--Length 14 to 17 mm. T. microcephalus was identified by Professor Hine. Two of the specimens were in rather poor con- 112 MINNESOTA TECHNICAL BULLETIN 80 dition. It has been heretofore reported from New Hampshire, Massa- chusetts, and New York.

Tabanus minusculus Hine 1907 Tabanus minusculus Hine, Ohio Nat. 8:226. 1921 Tabanus ininusculus Surcouf, Genera Insectorim, Fascicle 175, p. 76. This species was listed by Hine from Maine, New York, Massachu- setts, and Canada; Surcouf (1921) adds Utah. If the latter locality is correct, which is doubtful, further collecting in this state should reveal it here. Tabanus nivosus Osten Sacken 1876 Tabanus nivosus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2445. 1903 Tabanus nivosus Hine, Papers Ohio State Acad. Sci. No. 5 :52. 1926 Tabanus nivosus Cameron, Bull. Ent. Res. 1732. Specimens examined.-31 females, 15 males, Minnesota. The eyes of this species are bare, antennae black, wings hyaline, unclouded, and the abdomen has 3 rows of gray spots, the 2-lateral rows most prominent, and largest on the second .tergite. The eye pattern in living specimens consists, in the females, of a reduced purple dash in the center of the eye on a purplish-green ground, and in the male, of a single blue band on the small facets along. the line of demarcation from the larger facets. The area of large facets on dried males is usually buff or yellow with a central dark patch. Variations.—Length 12-16 mm. The size varies considerably, and most specimens have a pinkish ground color beneath the lateral spots of the abdomen. Separation.—The lateral, rhomboidal, pinkish-gray spots on the abdomenal tergites of this species are characteristic, and not to be confused with any other species, except reinwardtii, which has pilose eyes and clouds on the wings. Abundance.—Judging from the abundance of the larvae found, the adults must be more common in our fauna than supposed. Hine (1904) speaks of nivosus as readily attacking man, especially around the bathing beaches. It seems to have more retiring habits in Min- nesota: • Tabanus nudus McDunnough 1921 Tabanus mains McDunnough, Can. Ent. 53:143. Specimens examined.-57 females, 13 males, Minnesota; 6 females, Montana; 6 females, Saskatchewan. Antennae of this recently described member of the affinis gro.up have the first joint grayish, second ind third reddish with the excision infuscated apically merging into the black on the terminal segments. In the female, the subcallus is denuded, sloping into the reduced callosity above, and the pallid palpi are swollen, strongly tapering. Outer front tarsal claw and pulvillus of male twice as long as inner; the pale yellowish palpi are extremely swollen, almost round. Red on sides THE TABANIDAE OF MINNESOTA 1 13

of abdomen more extensive than in female, much as described for epistates. The eye color in fresh nudus females consists of 3 narrow purple stripes on a greenish ground, with lower margin often darker. The ocular color pattern in the male is essentially similar to that of the female. Variations and separation.—Length 14-17 mm. The extent of the reddish areas on the sides of the abdomen as well as that of the oblique yellow dashes within them, varies somewhat in this species. The broader front and denuded subcallus easily distinguish the females from epistates. In the latter, furthermore, the, fringe of bristles on the posterior tibiae is lighter. The bands continue narrow across the eyes of the males whereas in the males of Qffinis, with which they might be confused, at least the central band widens outwardly.. The greater size of the latter (18 mm.) and the subequal front tarsal claws will best distinguish them from the males of nuchts, which are 15 mm. in length and have the outer front tarsal claws almost double the length of the inner. The males of nudits and epistatcs are more difficult of separation, as indicated under that species. Abundance.—With the exception of one individual, all specimens have been taken in the northern part of the state. It is usually found in series with epistates, but none of the latter were taken with it in the early part of July, 1924, at Internatonal Falls, whether because of a difference in their seasonal occurrence or because of the unsually late spring was not ascertained. - At International Falls i i males and i female were taken at water and the other females were taken around stock.

Tabanus orion Osten Sacken 1876 Tabanus orion Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2442. 1905 Tabanus orion Washburn, loth Rept. Ent. Minn. 79. Specimens examined.—I female, Minnesota; i male, Pennsylvania; 2 females, Connecticut; i female Massachusetts. The Minnesota specimen is a little smaller, 22.5 mm., but it agrees well with Osten Sacken's description. It has a more reddish cast to the body, antennae, and legs, and a more robust form than actacon, its nearest relative. A single specimen taken in 1899 places this species in our fauna. It is probably of rare occurrence, its large size otherwise would have attracted more attention from collectors in this state. Its previous range, as given by Osten Sacken, was in the New England states and Canada. The eastern specimens studied are 25-26 mm. long in the females and 24.5 mm. in the male. The length of the male described by Osten Sacken was only 20 to 21 mm., but was probably unusually small. 114 MINNESOTA TECHNICAL BULLETIN 80

Tabanus osburni Hine Tabanus osburni Hine, Ohio Nat. 5:241. Specimens examined.-5 females, Minnesota; 6 females, Wyo- ming; 254 females, Montana; 3 females, Idaho; 2 females, Washing- ton; 5 females, Alberta; 2 females, British Columbia. Distinguishing characteristics.—This is a shining black-bodied species with

faint infuscation on the cross-veins and bifurcation of R4 and R5; 3 rows of indistinct, gray triangles on the abdomen. Antennae mostly blackish narrow, base - of third segment Ted. Subcallus and callus of female shining black, separated by a deep transverse sulcus. Male, as described by Hine, should be readily associated. Abundance.—All five specimens were taken at Red Lake Falls by the writer in July, 1925. This is an interesting addition to the horsefly fauna oi the state, the species apparently reaching the eastern limits of its distribution here. It is one of the bad pests of stock in Montana. Tabanus reinwardtii Wiedemann 1828 Tabanus reinwardtii Wiedemann, Auss. Zweifl. Ins. 1:130. 1876 Tabanus reinwardtii Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:461. 1903 Tabanus reinwardtii Hine, Papers Ohio State Acad. Sci. No. 5 :54. 1926 Tabanus reinwardtii Cameron, Bull. Ent. Res. 17:35.

Specimens examined.-26 females, 15 males, Minnesota; 2 females, Montana; 3 females, Ohio. T. reinwardtii has indistinctly pilose eyes, black antennae, hyaline wings with prominent isolated clouds, and abdomen with 3 rows of prominent gray spots largest on the second tergite. The gray front of the female is rather wide and characteristically marked, with a brown cross-band in the middle divided by the linear extension above the callosity. There is a shining brown spot on the vertex which might readily be mistaken superficially for the ocellar tubercle. The abdominal triangles are rather easily rendered indistinct in rubbed specimens. The reddish beneath the lateral oblique spots is more evident in the males than in the females but is variable in both. Abundance.—This species has been taken in the adult stage only near the fish hatchery at St. Peter and in the vicinity of University Farm. It is another of those species the larvae of which are rather common, but the adults themselves are of infrequent capture, and must therefore have obscure feeding habits.

Tabanus rhombicus Osten Sacken 1876 Tabanus rhombieus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2472. This species was listed by Washburn in 1905 and may have been taken by some of the earlier collectors, but no specimens of it from within the state are represented in the University collection. Four specimens from South Dakota, however, indicate that it is likely to be taken here in the future collecting. Andrews (1918) has also reported a specimen taken at Whitefish Point, Northern Michigan. THE TABANIDAE OF MINNESOTA 115

Tabanus sagax Osten Sacken 1876 Tabanus sagax Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:452. 1906 Tabanus sagax Hine, Ohio, Nat. 7:26. 1914 Tabanus sagax Hine, Ohio Nat. 14226. 1918 Tabanus sagax MeAtee and Walton, Proc. Ent. Soc. Wash. 20204. Minnesota was included among the localities in the original description of T. sagax, but it has not been recognized among the specimens in the collection. It should be easily separated from any of the species in our fauna by the mid-dorsal longitudinal stripe on the brownish abdomen with rounded lateral spots, the dilute yellowish costal cell and lack of a prominent angle at the base of the third antennal segment. Tabanus septentrionalis Loew 1858 Tabanus septentrionalis Loew, Vern. Zool.-Bot. Ges. 8:592. 1876 Tabanus septentrionalis Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:454. 1923 Tabanus septentrionalis Hine, Can. Ent. 55:145. 1925 Tabanus labradorensis Enderlein, Mitt. Zool. Mus. Berlin ii :363. 1926 Tabanus septenfrionalis Cameron, Bull. Ent. Res. 17:37. 1927 Tabanus canadensis Curran, Can. Ent. 59:37. Specimens examined.—I94 females, Minnesota; 45 females, Mon- tana; 3 females, Wyoming; 3 females, Saskatchewan; 2 females, Al- berta. Loew's original description characterizes the antennae as black with only the extreme base of the third segment sometimes reddish; the latter but little excised. Palpi dirty white with black hairs on the second segment and at the end of the first. Face and cheeks yellowish gray, beset with black and pale yellow hairs. Length 13 mm. Type from Labrador. Variations.—io.5 to 16.5 mm. A long series of specimens from Minnesota and certain other localities in the West examined by the writer differ from the typical description in that the antennae are usually more reddish on the third segment, in extreme instances covering practically the whole of that segment. A few black hairs occur very infrequently on the firk palpal segment and practically never on the cheeks. The coloration of the abdomen varies both in well preserved and in rubbed specimens, but only occasionally are the basal abdominal tergites without reddish lateral spots rounded on their median and hind margins. This rounding is accentuated by the distribution of the appressed light and dark hairs which compose the three rows of spots. A grayish golden, pollinose suffusion together with the rather slender, characteristic form facilitate recognition of specimens in series of other species bearing them a superficial resemblance. The variability of septentrionalis has led many writers to suggest a possible composite group, as it has been considered. Osten Sacken 116 MINNESOTA TECHNICAL BULLETIN 80 grouped 20 specimens in four series from localities as widely separated as Alaska and Labrador and confessed himself. dissatisfied to attempt a specific separation from the typical form. Both Enderlein and Curran have described species with slight morphological or color differences. The former described labradorensis on the color of the hairs of the venter, the presence of a stump on vein R4, and a slight difference in the width of the antennae. Curran separated canadensis on small size, (12 to 13.5 mm.), differences of palpi, and first tarsal segments, almost complete absence of black hairs on hind femora, and color. However, Loew's original measurement was 13 mm., and all of the above characters appear to be mutable to a certain extent in the specimens before me, certain specimens over 15 mm. fitting the description of canadensis as well as sthaller individuals. Three specimens from Saskatchewan (14.5 to 15.5 mm.) on the other hand, show from 3 to 12 black hairs on the first palpal joint and varying numbers on the posterior femur, thus coming nearer the original description than any of the Minnesota specimens. The others from Banff, Alberta (12 and 12.5 mm.), with almost no red on the abdomen, have a very few black hairs on the first Palpal joint and on the posterior femora. Intergrades occur that appear to justify Osten Sacken's hesitancy for specific designation even with his limited material. Labradorensis and canadensis appear to warrant separation of no more than varietal rank at the most, unless the whole of the western group is accepted as different from the original Labrador type. Abundance.—A very abundant species at certain times in the northwestern part of the state. It is only infrequently taken in the southern half. Tabanus stygius Say 1823 Tabanus stygius Say, Jour. Acad. Nat. Sci. Phil. 3:33. 1876 Tabanus stygius Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:454. 1903 Tabanus stygius Hine, Papers Ohio State Acad. Sci. No. 5 :54. Specimens examined.-29 females, 22 males, Minnesota; 6 females, Ohio. Size large, wings smoky brown with darker clouds on the cross-veins and thoracic dorsum of bifurcation of veins R4 and R„ body and legs dark, with the the female whitish—all serve to characterize T. stygius. The eye colors in the female consist of 2 abbreviated puplish bands above and a lower cross-band reaching the posterior margin of the eye, on a dark greenish ground. Separation.—T. nigrescens Pal. has not been taken in this state but is mentioned by Hart (1895) from Illinois; the dark dorsum of the thorax will separate females of the latter from those of stygins. T. subniger Coq., described from northern Illinois, 'might occur in the extreme southeastern part of Minnesota and may be distinguished by its larger size and the "white hairs along the sides and apex" of the THE TABANIDAE OF MINNESOTA 117

abdomen. T. punctifer, which has a western distribution very similar to that of Chrysops fulvaster and therefore might doubtfully come into our fauna in the extreme southwest, is distinguished by its bicolored front tibiae, which are white proximally. Abundance.-Like atratus, stygius is a strong flier and is taken less frequently even than that species. It is represented in the collection from the southeastern portion of the state, altho it is commonly found as larvae in Ramsey and Hennepin Counties.

Tabanus sulcifrons Macquart 1855 Tabanus sulcifrons Macquart, Dipt. Exot. Suppl. 5:33. This species has been recorded from the Mississippi Valley as far north as Illinois and Nebraska. Some intensive collecting will probably reveal it at least along the Mississippi River in the extreme southeastern corner of the state.

Tabanus trepidus McDunnough 1921 Tabanus trepidus McDunnough, Can. Ent. 53:142. Specimens examined.-23 females, Minnesota; i female, Ottawa. The females of this species are characterized by their deep orange and extremely long, slender palpi which should distinguish them from those of the affinis group without the denuded subcallus, with which they might be confused; in addition, the greater excision of the antennae in affinis and graci/ipa/pis, and the narrower front in the latter, also serve to separate those species. The eye pattern of the female consists of 3 blue bands, the upper and lower ones bending to meet the middle one at their outer end; the lower margin is also blue, and the green intervals are narrow. Length 14.5-16 mm. The male is unknown. Occurrence.-The specimens have all been taken in the northern half of the state, where the species occurs uncommonly with other more abundant species of the affinis group.

Tabanus trimaculatus Palisot de Beauvois 1807 Tabanus trimaculatus Palisot de Beauvois, Ins. Rec. A fr. et Amer. 55. 1876 Tabanus frimaculatus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:439. 1903 Tabanus trimaculatus Hine, Papers Ohio State Acad. Sci. No. 5 :55. Specimens examined.-46 females, 26 males, Minnesota; i female, Kansas; 2 females, Georgia. This species is easily recognized by the whitish pollinose thorax with brownish ground color, and the black abdomen with 3 subequal white triangles on the third, fourth, and fifth tergites. An occasional specimen exhibits small whitish spots laterally on the second tergite also. This, like stygitts, has been taken infrequently in the adult stage and only in the southeastern portion of the state. The larvae out- number by far any other species taken but the adults seem to have retiring habits in Minnesota. 118 MINNESOTA TECHNICAL BULLETIN 80

Tabanus trispilus Wiedemann 1828 Tabanus trispilus Wiedemann, Auss. Zweift. Ins. 1:150. 1876 Tabanus trispilus Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:464. 1918 Tabanus trispilus McAtee and Walton, Proc. Ent. Soc. Wash. 20:205. Specimens examined.-12 females, 2 males, Minnesota; i female, Virginia. This is a dusky species with uniformly smoky wings and a series of contrasting mid-dorsal light triangles on the abdomen, largest on the second and third segments. The triangles in the male are more reduced; the outer front tarsal claw and pulvillus are half again as long as the inner; the vestiture of the thoracic pleurae is mostly dark in this sex, sparcely mixed with pale hairs, that on the postalar callus being entirely pale yellowish in contrast; the antennae of the male have the red on the third segment confined to basal third. The pleurae of the females are clothed with dark and light hairs about equally merging into pale gray; entirely light gray posteriorly. The pilosity of the eyes in the female is indistinct but there is a definite ocelligerous tubercle. Variations.—Length 12-16 mm. Considerable variation occurs in the wing color from a dilute brownish to a smoky gray, an observation made by Johnson (1919). Occurrence.—Except for those taken near the fish hatchery at St. Peter, the vicinity of University Farm is the only locality in which trispilus has been taken within the state. It seems to appear late in the season, judging by the few records we have. McAtee and Walton (1918) mention taking it on flowers of chinquaquin and Ceanothus. Tabanus zonalis Kirby 1837 Tabanus zonalis Kirby, Fauna Bor. Amer. 4:314. 1876 Tabanus zonalis Osten Sacken, Mem. Bost. Soc. Nat. Hist. 2:463. 1904 Tabanus zonalis Hine, Ohio Nat. 5:224. Specimens examined.-20 females, 2 males, Minnesota; i female, Massachusetts; i female, Nova Scotia. The wings are uniformly tinged with yellowish and the abdominal segments are black with prominent yellowish incisures giving T. zonalis an exotic appearance. The incisures of the 2 males studied are much lighter in color, being almost white. Variations.—Length 15-18.5 mm. The yellow posterior margins of the abdominal segments vary considerably in width and intensity of color, fading in older specimens to a grayish yellow. The intensity of the dense black hairs over the palpi makes the latter appear black in most specimens. Abundance.—This species bears a superficial resemblance to some of the Hymenoptera, and it is exceedingly wary. While not as numerous as many other species in the north, where it seems to be most prevalent, it is very troublesome to stock. THE TABANIDAE OF MINNESOTA I19

A number of males were observed visiting a small roadside puddle at International Falls. Because of their extreme wariness and manner of taking water, without circling over it as the males of certain other species did, only two were captured.

CLASSIFICATION OF KNOWN IMMATURE STAGES OF MINNESOTA SPECIES Key to Genera The developmental stages of Si/viits and Bup/ez and the egg stage of Haematopota americana are yet to be discovered and are therefore not included in the following keys. Patton and Cragg (1913) and Cameron (1930) report observations on oviposition in Haematopota, the former authors reporting eggs in the field as laid "in one or more layers on blades of grass," And Cameron on eggs laid by females in confinement. Special terminology used in the following keys will be understood by reference to the illustrations, particularly of the immature stages of T. lasiophthalmus. Preservation of the larval exuviae and pupal shells has been found to be invaluable in the study of the immature stages, the former being preserved in alcohol with the proper serial reference, and the pupa glued to a slip of stiff paper attached to the pinned adult. Otherwise a few preserved specimens taken with a series at a particular collection may be confused where more than one species is reared from the stne lot. The rearing technic used by the writer (1928) is best suited to recovery of larval skins. 1. Eggs in one layer, overlapping and sloping upward Chrysops Eggs in a mass, "haystacklike," an elevated subcopical mass of several layers' Tabanus Larval Stages As previously mentioned, the last instar, or mature larva, of any species is most frequently taken in the field, especially from April to June. The following keys are drawn up with these occasions in mind. The less frequent younger in.stars of the larvae of certain Tabanus sometimes resemble Chrysops very closely. However, a considerable difference that can be of aid in separation, is found in the size of the head, those of Tabanus being some four or five times as large in larvae that are otherwise of similar size.

9 Isaacs (1926), in India, found two species of Tabanus which lay their eggs in single layers like Chrysops. There appears to be a difference in number of eggs laid, such masses being more elongate. On the other hand, C. celer has been observed by Hine in North America as being the only known species of Chrysops ovipositing in more than one layer. It may also be noted that certain egg masses of Stratiomyidae are easily confused with those of Tabanus, being laid on emergent vegetation along margins of ponds, but they are usually lighter in color, and the eggs are not as closely packed together. 120 MINNESOTA TECHNICAL BULLETIN 80

1. Larvae small, when mature, usually less than 20 mm.; second and third antennal joints subequal, or the distal the longer; tracheal trunks (seen in living larvae) unswollen, sinuous; usually a protrusile stigmatal spine; body almost entirely striated Chrysops Larvae mostly large or very large when mature, usually over 20 mm.; antennae with terminal joint much the shorter and smaller; tracheal trunks usually swollen; almost never with protrusile spine at tip of siphon; ventral and dorsal areas often smooth especially on thorax... 2 2. Larvae with anal segment rounded, the siphon short, hardly exsertile ; dark ornamentation confined to anal and three thoracic segments...Haematopota Larvae with anal segment usually tapering, a more or less elongate siphon when extended; dark markings, when present, usually on other abdominal segments as well, or confined to a prothoracic collar only.. Tabanus

Pupal Stages Pupal characters are plastic and difficulties arise in finding any that are constant and not subject to some variation. The relative positions and shapes of the thoracic spiracles have been used. In Chrysops these spiracles are generally more inclined toward the vertical than in the others, but variations have been observed even on the same specimen. A male of T. lasiophthalinus before the writer has the left spiracle on the thorax semi-circular and even the right one slightly more curved than usual. The frontal carinae and adjacent rugosity sometimes offer good characters but frequently vary within the species as do the length and density of abdominal spinose fringes. The positions of the bristle-bearing tubercles on the thorax and first abdominal segment are usually constant and so are the numbers of the bristles. Differences in presence or absence of bristles as figured in the literature, at certain positions corresponding to those figured on T. lasiophthalrnus, Fig. 10, are probably due to breakage rather than to being originally absent. Considerable variation occurs in the relative positions of the three lateral bristles on the first abdominal segment, in some specimens the two lower even combining on the coalesced tubercles. But their use in a specific key proved impractical at present. The aberrant appearance of a few spines on the dorsum of the first segment corresponding to the fringes on the second and following segments has been noted several times. In nearly all Chrysops pupae examined the tips of the antennae were slightly notched. The characters of comparative antennal length and relation of the tip to the "adjacent margin of the head" introduced by Hart, have proved generically constant in all specimens studied by the writer. Later Malloch used "lateral margin of head" to designate the suture which splits at the time of emergence and passes beneath the tips of the antennae in Chrysops, but is usually not reached by the antennae in Tabanus. In unemerged specimens this suture is difficult to dis- THE TABANIDAE OF MINNESOTA 121 tinguish and care must be used not to confuse it with the posterior margin of the head. It does not constitute a real margin of the head, however, and for this reason a different terminology has been used in the following key. The pupal aster, so widely figured in the literature as of diagnostic value for the species of Tabanus, was found of little value for comparison in the species of Chrysops, and in any event is of limited use in keys. The number of spines in the combs and ventral fringes of the anal segments can not be relied upon solely;.particularly in Chrysops do the numbers of spines in the anal fringe of the males vary, where long series are available for study. 1. Dorso-lateral and lateral combs absent on caudal segment; bristles on frontal tubercles double; antennae about twice as long as basal width, surpassing adjacent line of dehiscence (best seen after emergence) Chrysops Dorso-.lateral or lateral combs present; frontal bristles single; antennae long or short 2 2. Antennae elongate, the tip surpassing the adjacent line of dehiscence Haematopota Antennae short, only about as long as basal width; the tip not attaining adjacent line of dehiscence Tabanus

Chrysops All larvae of this genus seen by the writer have more or less definite dark annuli; these may be less noticeable in certain specimens that were apparently bleached by preservation soon after molting. The distribution of the striae on the thoracic segments is of less use here than in separation of the species of Tabanus. The chief differential characters are to be found in the anal segment where the distribution of the pigmented or pubescent areas varies with the species. Un- fortunately, altho these "dark pictures" on the anal segment are constant within certain types for a given species, they are frequently variable in exact contour, and are sometimes .not even bilaterally symmetrical in pattern on the same specimen. This was especially noticed in C. montanus larvae. The following table is offered provisionally with the probability that a long series of larvae will produce specimens that will be difficult to determine. It is also realized that variations in the degree to which the larva is extended vill cause differences in the width of the posterior pigmented band On the anal segment. However, the key has been drawn up with the usual position of semi-retracted siphon in mind. In any event, the determination of the immature stages will usually supplement rearings of the adults except in the instances where preserved material only is available, or in the event of observations in the field. 122 MINNESOTA TECHNICAL BULLETIN 80

The close relationship noticed between the adults of C. callidus and C. aestuans is also seen in the larvae and pupae, no characters for their separation satisfactory to the writer having been found, altho Stone (1930) has separated the larvae in his key. The following key has been adapted with permission from that author.

KEY TO THE LARVAE OF CHRYSOPS

1. Siphon without a terminal exsertile spine 2 Siphon with a terminal exsertile spine 5 2. Anal segment slender; prolegs of the pre-anal segment elongate; pre-anal segment dorsally with some pubescence 3 Anal segment not very slender; prolegs short and rounded; pre-anal segment non-pubescent dorsally except for a very narrow pubescence along the dorso-lateral line 4 - 3. Dorsum of pre-anal segment distinctly non-pubescent distally cuctux Dorsum of pre-anal segment rather uniformly faintly pubescent moechus 4. Anal segment with one or two pairs of prominent dorso-lateral spots; body usually brownish green in color., carbonarius Anal segment with only one, small, dorso-lateral spot; body usually whitish or creamy in color vittatus 5. Dark band on posterior margin of the anal segment wide, occupying at least a third, fr'equently half or more of the dorsum in the middle.... io Dark band narrow in the middle above, less than third 6 6. Dorso-lateral and lateral maculations on anal segment narrow, linear longitudinally 7 These spots not linear, in the form of blotches 8 7. Posterior band joined to anal pubescence ventrally sackeni Posterior band separated from anal pubescence striatits 8. Posterior band narrow around entire anal segment, separated from anal pubescence; a narrow band prominent around posterior margin of the 7th segment also excitans Posterior band joins anal pubescence; no posterior band on pre-anal segment 9 9. Dorso-lateral spots merged to form a large blotch connecting with anterior margin of anal segment mitis Dorso-lateral spots often in two pairs; tracheal trunks in the 6th and 7th segments contrasting black and opaque white celer io. Posterior band on anal segment very broad, one-half to two-thirds length of segment, abruptly projected ventro-laterally to the anterior incisure, enveloping the anus fulvaster Posterior band dorsally occupying between one-third and one-half of anal segment Anal segment with a pair of anterior dorso-lateral projections from the posterior band 12 No anterior dorso-lateral projections or spots; a pair of large clear dorso- lateral areas in the posterior band montanus 12. Anterior projections from the posterior band long and slender aestuans Anterior projections short and rounded 13 THE TABANIDAE OF MINNESOTA 123

13. Anal segment with no isolated pubescent spots anterior to the posterior band callidus Anal segment with one or two pairs of dorso-lateral spots 14 14. Anal segment with two projections from the posterior band between the dorsum and the anus niger Anal segment with only one dorso-lateral projection 15 15. Dorso-lateral projections from the posterior band not abruptly narrowed apically ; dorso-lateral spots large, lying close between the dorsum and the anus wiedemanni Dorso-lateral projections abruptly narrowed apically indus

Key to Pupae of Chrysops The terminal teeth (asters) of Chrysops pupae are not notably variable in the various Minnesota species. Only the anal segment of C. montanus has been figured, therefore (Fig. II). 1. Front with pair of carinae on either side the middle between the antennae strongly developed, more or less divided narrowly by a sulcus into two pairs, the median and the more reduced lateral pairs (Fig. 20); or the carinal ridge may be continuous, the median and lateral portions indicated only by a dip in the ridge Front with median pair of frontal carinae strong or reduced, but the lateral pair obsolescent, widely separated from the median 2 2. Median pair of frontal carinae very much reduced, rounded, the lateral pair not in evidence wiedemanni Median pair not extremely reduced, the carinal ridge sharp; lateral pair usually present at least as rounded knobs 3 3. Median pair strongly projecting and evenly arched, narrow at base, lateral carinae absent or more swellings striatus Median pair brbad basally, if prominent, not evenly arched, highest in- wardly 4 4. Abdominal fringes of spines relatively long, slender ercitans Abdominal fringes of spines reduced, extremely short on the dorsum of the second and third segments 5 5. Abdominal fringes composed of coarse, short spines, broad at base, spaced about the width of the spines montanus Abdominal fringes composed of extremely small stout spines, very closely set together, usually about half the width of the spines between, most of those on dorsum of second segment reduced to mere points sackeni 6. Median portion of frontal carinae over twice the width of the lateral portion, the ridge usually continuous (also occasionally in indus) ; disc of thoracic spiracle relatively smooth especially on anterior portion; tubercle above base of wings usually with a single bristle mitis Median and lateral pairs of carinae usually subequal, the ridge seldom continuous;; disc of spiracle heavily serrated on inferior margin extending caudad of rima ; double bristle above base of wings 7 7. Disc .of spiracle subrectangular, projected beyond the hooked anterior end of the rima making the width at either end subequal ; dorsal abdominal fringes composed mostly of relatively slender, rather long spines....indus 124 MINNESOTA TECHNICAL BULLETIN 80

Disc of spiracle subtriangular, apex of disc terminating at the anterior end of the rima, the latter and the serrate margin diverging widely toward the caudad end; dorsal abdominal fringes composed mostly of short, rather stout spines, shortest in middle of second segment callidus, aestuans

TABANUS Key to Larvae 1. Larvae with slender tracheal tubes much as in Chrysops (as seen in living larvae) certain terrestrial species Larvae with swollen tracheal trunks 2 2. A sharp, protrusile stigmatal spine, sometimes more or less retracted in preserved specimens; lips of spiracle not chitinized but fleshly and somewhat pointed 3 No stigmatal spine; lips of spiracle with prominent chitinous margins, rounded or barely convex 4 3. Larvae, when mature, very large, about 40 mm., usually yellowish; a pair of prominent tubercles bearing three stiff hairs each, on the tip of the siphon either side of the spiracle stygius Larvae, when mature, medium sized, 20 to 25 mm., whitish, less ornate..Thzeola 4. Meso- and metathoracic dark bands with 4 lateral projections reaching at least half way to the posterior margin 5 If bands present, light and without long lateral stripes 7 5. Very large larvae when mature, 40 mm. or more; heavily ornate; the lateral thoracic stripes widened posteriorly, club-shaped atratus Smaller larvae when mature, usually under 35 mm.; lateral thoracic stripes slender 6 6. Thoracic stripes subequal ; no dorso-lateral, isolated spot cephalad above the rather small declining lateral row of spots on the anal segment; this segment usually tapering, the siphon elongate, dark when extended trimaculatus Thoracic stripes longest on second segment, those on the third little more than half its length; an isolated spot dorso-laterally on the anterior margin, the row of declining spots below it heavier; anal segment usually rounded, siphon when extended, rather short reinwardtii 7. Larvae with a series of dorso-lateral, short dark dashes which may or may not be connected by faint shading; translucent brown or green in life Larvae chiefly whitish, maculations, if present, not prominent except for accumulation of dirt on pseudopods 8. Anal siphon very short; body completely covered with striae; thoracic segments with faint narrow rings anteriorly trispi/us Anal siphon moderately elongate; body smooth and shining on the dorsum and venter, striated laterally; no dark annuli nivosus 9. Dashes confined to abdominal region; no pubscent bands on anterior margin of meso- and metathoracic segments /asiophthaimus• Dashes extending onto thorax also; pubescent bands connecting these across or running around thoracic segments anteriorly io so. Small larvae, when mature, 25 mm.; thoracic bands pale, not evident on the abdomen Riotus THE TABANIDAE OF MINNESOTA 125

Larger larvae when mature, 30 mm.; anterior thoracic and posterior rings on 7th abdominal segment dark; sides of anal segment frequently with dark spot septentrionalis

Key to Pupae of Tabanus 1. Second and following abdominal segments with complete circlets or fringes of spines 2 Second abdominal segment ventrally with spines confined to a few in the middle, and reduced laterally to a less extent on the two following segments reinwardtii 2. Dorso-lateral and lateral combs present 3 Dorso-lateral combs wanting, lateral comb usually reduced lineola 3. Large species, usually over 25 mm.; teeth of pupal aster low, their points marking the angles of a broad hexagon Smaller species, usually much less than 25 mm.; terminal teeth usually elongate, without hexagonal arrangement 5 4. Long spines of dorsal abdominal fringes annulated and tipped with blaCk atrat'us Long spines tipped with black but not ringed mesally stygius 5. Spines of dorso-lateral and lateral combs on last segment and those on the venter of the second segment laterally extremely reduced, small points only trispi/us Spines in these locations not reduced 6 6. Dorso-lateral comb with 6 or more strong spines 7 Dorso-lateral comb usually composed of less than 5 spines 8 7. Pupa normally dark reddish brown; dorsal abdominal fringes of spines, slender, bristle-like; frontal carinae contiguous mesally in the male, separated but strong, and rugose in the female nivosus Pupa normally light or yellowish brown; dorsal abdominal rows of spines shorter, rather stout; frontal carinae widely separated in male and female, those of latter low, slightly rugose trimaculatus 8. Rows of long and short spines on dorsum of abdomen especially caudally about even in numbers 9 Long spines almost absent mesally on the dorsum, the short ones in the middle of the second segment reduced to mere stout points epistates 9. Thoracic spiracle hooked at its anterior end, the upper inner margin strongly turned upon itself at that point; spines of the caudal fringe • below the aster in the male numerous, 9 or more on each side not including the lateral comb illotits Thoracic spiracle gently curved, the cephalic end not hooked, the inner margin merely encompassing the width of the rima ; caudal fringe of male with fewer, stronger spines, 7 or less on each side....lasiophthalmus

SUMMARY The Tabanidae comprise a family of flies of considerable economic consequence in Minnesota. Three genera and 47 species are definitely known to have been taken within the state. Only a few species of the robust horseflies of the genus Tabanus and of the smaller pictured- winged deerflies of Chrysops occur in abundance enough to be con- 126 MINNESOTA TECHNICAL BULLETIN 80 sidered pests. The muskeg portions of the state in the north offer unusually good opportunities for their breeding, and incredible numbers of the flies abound during June and early July. Observations on the bionomical activities of the adult flies—their habits, seasonal and geographic distribution; and on the immature stages of certain species in Minnesota are recorded. T. lasiophthalmus, a troublesome species of some abundance particularly in the muskeg sections of the north, was reared from field-collected eggs and found to have nine larval instars from the time of hatching in June to pupation in the following spring, under laboratory conditions. It appears probable that most species have one generation a year under these climatic conditions. Hibernation is accomplished in the larval stage. Other species reared from larvae or pupae taken in the field were T. epistates, T. illotus, T. lineola, T. nivosus, T. reinwardtii, T. stygius, T. trimaculatus, C. aestuans,'C. callidus, C. carbonarius, C. excitans, C. indus, C. mitis, C, montanus, C. zviedemanni, C. sakeni, and C. striatus. The development of a new pair of "black bodies" in Graber's organ during each larval stadium was observed in both Chrysops and Tabanus. The number of bodies varies particularly in mature individuals and, therefore, can not be used taxonomically. New information is also presented regarding the number of spiracular openings in the larvae. The physical factors of the environmental resistance are discussed and it is considered likely that the rigors of winter do not kill many larvae during hibernation. Of the biotic factors, the cannibalistic nature of Tabanus larvae appears to be of potential importance in reducing the numbers of tabanids before pupation. Three hymenopterous parasites were reared from eggs, Phanurus emersoni from both Tabanus and Chrysops eggs, and Trichogramma minutum and Anap- hoidea sp. from those of Chrysops. A new species of tachinid fly was reared from Tabanus larvae; and the hymenopteron, Diglochis occidentalis, was reared from pupae of Chrysops mitis. Nematodes were found attacking larvae and pupae of several species, and in one instance an adult of T. metabolus, all taken in the field. Dichotomous keys are presented and brief comments noted regarding variations from previous descriptions, as an aid to identification of adults of Minnesota species. Three new species are described, T. dawsoni, T. fulvicallus, and T. longiglossus. Keys to the known immature stages also are included. THE TABANIDAE OF MINNESOTA 127

V. TAXONOMIC REFERENCES Andrews, A. W. 1918 Diptera collected on Whitefish Point, Chippewa County, Michigan. Occas. Papers Univ. Mich. No. 53, 8 pp. Bequaert, J. 1924 Notes upon Surcouf's treatment of the Tabanidae in the Genera Insectorum and upon Enderlein's proposed new classification of this family. Psyche 31:24-40. Bromley, S. W. 1926. The external anatomy of the black horsefly Tabanus atratus, Fabr. Ann. Ent. Soc. Amer. 19440-60. Cameron, A. E. 1930 Oviposition of Haeinatopoia pluvialis Linne. Nature 126:601-02. Daecke, E. 1906 On the eye-coloration of the genus Chrysops. Ent. News 17:39-43. 1907 Annotated list of the species of Chrysops occurring in New Jersey and descriptions of two new species. Ent. News 18:139-46. Hart, G. A. 1895 On the entomology of the Illinois River and adjacent waters. Bull. Ill. State Lab. Nat. Hist. 4:220-47. Hine, J. S. 1907 Second report upon the horseflies of Louisiana. La. Agr. Expt. Sta. Bull. 93:1-59. Isaacs, P. V. 1926 Papers on Indian Tabanidae. VIII. The Bionomics and life-histories of some of the common Tabanidae of Pusa. Agr. Res. Inst., Pusa, India, Dept. Agr. Memoirs, Ent. series, Calcutta. 9:21-8. Johnson, C. W. 1919 Tabanus atratus Fabricius, var. n. fit/vopllosus. Psyche 26:164. Krober, 0. 1926 Die Chrysops—Arten Nordamerikas einschl. Mexicos. Stettiner ento- mologische Zeitung 87(2):209-353. Lugger, 0. 1896 Insects injurious in 1896. Minn. Agr. Expt. Sta. Bull. 48. Marchand, W. 1918 The evolution of the abdominal pattern in Tabanidae (Diptera). Trans. Am. Ent. Soc. 44:171-9. Patton, W. S. and Cragg, F. W. 1913 Textbook of medical entomology. Christian Literature Society for India, London, Madras and Calcutta. Shannon, R. C. and Bromley, S. W. 1924 Radial venation in the Brachycera (Diptera). Insec. Ins. Mens. 12:137-44. Stone, A. 1930 The bionomics of some Tabanidae (Diptera). Ann. Ent. Soc. Amer. 23:381-89. Tillyard, R. J. 1919 The Panorpoid complex. Part 3. The wing venation. Proc. Linn. Soc. N. S. W. Sydney 44:533-718. 128 MINNESOTA TECHNICAL BULLETIN 80.

Townsend, C. H. T. 1895 Contributions to the dipterology of North America. II. Tabanidae, Conopidae, Tachinidae, etc. Trans. Amer. Ent. Soc. 22:55-60. Washburn, F. L. 1905 The Diptera of Minnesota. loth Rept. State Ent. of Minn. Tabanidae. Pp- 76-79. Wehr, E. E. 1922 A synopsis of the Tabanidae of Nebraska. Nebr. University Studies 22 a08-18. Williston, S. W. 1886 Notes and descriptions of North American Tabanidae. Trans. Kan. Acad. Sci. 10:129-42. FIG. 4 3 4 5 8' IN5TAR 5ept. J. J(.1y Tact •

Tat.

• • • •

FIG. 5

PLATE I Fig. 4. Wing of Tabanus (Terminology after Comstock and Needham) Fig. 5. Graber's Organ in Larvae of Tabanus lasiophthalinus. Diagrammatic Rep- resentation of Changes and Variations in Numbers of Bodies During Successive Instars. Greatly Enlarged

129 7

9 PLATE II Fig. 6. Mature Larva of Tabanus lasiophthalmus. Dorsal View. X 6.5 Fig. 7. Anal Segment of Same. Lateral View. X 18 Fig. 8. Anal Segment of Male Pupa and Dorso-Lateral Comb. X 35 and 8o, Respectively Fig. 9. Same of Female Pupa. X 35 Fig. Io. Pupa of Tabanus lasiophthalmus. X 7.5

130 13

15 16

PLATE III Fig. ii. Anal Segment of Male Pupa of Chrysops montanus Fig. 12. Same of T. lineola Fig. 13. Same of T. trimaculatus, with Dorso-Lateral Comb Fig. 14. Same of T. epistates Fig. 15. Same of T. trispilus Fig. 16. Same of T. reinwardtii (All to same scale—X 35)

131 17 18

19 20

PLATE IV Fig. 17. Anal Segment and Dorso-Lateral Comb of Male Pupa of T. illotus X 35 X 90 Fig. 18. Same of T. nivosus. X 35 X 90 Fig. 19. Same of. T. stygius. X 35 X 90 Showing Elongat( Fig. 20. Head Shield of Pupa of C. callidus After Emergence, Antenna! Sheaths Beyond Adjacent Margin, Frontal Tubercles with Paired Bristles, and Frontal Carinae Deeply Sulcate Later- ally Forming 2 Subequal Pairs. Dorsal vim X 30 t Fig. 21. Head Shield of Pupa of T. lasiophthalmus After Emergence Showin Short Antennal Sheaths, Frontal Carinae Contiguous Mesally, Hardly Sulcate Laterally. Dorsal view X 25

132 1