LIBRAR Y ■JRD FEBE- Î961 THE U. s. DtPÁ¡<,,>^iMl OF AGidCÜLl-yí MOSQUITOES OF ALASKA
Agriculture Handbook No. 182
Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE U < The purpose of this handbook is to present information on the biology, distribu- tion, identification, and control of the species of mosquitoes known to occur in Alaska. Much of this information has been published in short papers in various journals and is not readily available to those who need a comprehensive treatise on this subject ; some of the material has not been published before. The information l)r()UKlit together here will serve as a guide for individuals and communities that have an interest and responsibility in mosquito problems in Alaska. In addition, the military services will have considerable use for this publication at their various installations in Alaska.
CuUseta alaskaensis, one of the large "snow mosquitoes" that overwinter as adults and emerge from hiber- nation while much of the winter snow is on the ground. In some localities this species is suJBBciently abundant to cause serious annoy- ance. THE MOSQUITOES OF ALASKA
By C. M. GJULLIN, R. I. SAILER, ALAN STONE, and B. V. TRAVIS
Agriculture Handbook No. 182
Agricultural Research Service
UNITED STATES DEPARTMENT OF AGRICULTURE
Washington, D.C. Issued January 1961
For «ale by the Superintendent of Document«. U.S. Government Printing Office Washington 25, D.C. - Price 45 cent» Contents Page Page History of mosquito abundance Biology—Continued and control 1 Oviposition 25 Mosquito literature 3 Hibernation 25 Economic losses 4 Surveys of the mosquito problem. 25 Mosquito-control organizations 5 Mosquito surveys 25 Life history 5 Engineering surveys 29 Eggs_". 6 Methods of mosquito control 29 Larvae 6 Control of larvae 30 Pupae 6 Environmental control-., 30 Adults 6 Control with insecticides. 31 Distribution 7 Protection against adults 32 Abundance 11 Personal protection 33 Predicting abundance 12 Insecticides 34 Effects of weather on mos- Control of resistant mosqui- quito activity 14 toes 39 Biology 16 Technique for mosquito collection Larval habitats 16 and survey 39 Habitat preferences and Identification of species 42 relative economic im- portance of species 21 Keys and notes for identification. 42 Water temperature of Genus Aedes Meigen 45 larval habitats 22 Genus Culiseta Felt 71 Adult food habits 23 Genus Anopheles Meigen 77 Longevity 23 Genus Culex Linnaeus 79 Flight range 23 Literature cited 81 Mating 24 Appendix 87 n THE MOSQUITOES OF ALASKA
By C. M. GJULLIN, R. I. SAILER. ALAN STONE, and B. V. TRAVIS.^ entomologists, Entomology Research Division, Agricultural Research Service
History of Mosquito Abundance and Control
The mosquito problem in Alaska fever. . . . The traveler who exposes his seems to have changed very little bare eyes or face here loses his natural since it was first recorded by early appearance; his eyelids swell up and close, and his face becomes one mass of travelers and explorers. The first lumps and fiery pimples. Mosquitoes reconnaissance of Alaska after its torture the Indian dogs to death, espe- purchase from Russia in 1867 was cially if one of these animals, by mange made by Raymond (94.) ^ of the or otherwise, loses an inconsiderable portion of its thick hairy covering, and U.S. Army Engineer Corps in 1869. even drive the bear and the deer into During his voyage up the Yukon the water. River by steamboat, mosquitoes During a military reconnaissance were present in large numbers. He of the Copper River Valley in 1898 wrote : under the direction of Abenjrombie The swarms of mosquitoes and gnats (i), captain of the Second U.S. which abound on the river during the Infantry, a party led by Rafferty months of June and July proved a very serious annoyance. When the boat was (91) investigated the route from not in motion, we were obliged to wear Valdez to Copper Center on the face nets and gloves; and on one occa- Klutina River. His party camped sion an attempt to make sextant obser- for several days at Copper Center. vations failed completely from this cause. The mosquitoes are much larger He described the mosquito situation than those met with in lower latitudes. at that time (June 9-13) as follows : Petrof (89), while investigating The long-expected pests, the mosqui- toes, were out in full force during the the population and resources of stay at this camp, and the men were com- Alaska m 1880, found mosquitoes to pelled to wear veils day and night, with be a severe annoyance in the lower gloves to protect the hands. The feroc- Kuskokwim Valley. He wrote : ity of these mosquitoes I regard as some- thing remarkable. The species found There is another feature in this coun- here is not the large, singing sort seen try which, though insignificant on pa- in the States, but a small, silent, busi- per, is to the traveler the most terrible ness-like insect, sharp of bill, who touches and poignant infliction he can be called the tender spot in a surprisingly short upon to bear in a new land. I refer to time after alighting. After making their the clouds of bloodthirsty mosquitoes, ac- ~ appearance they never left the expedi- companied by a vindictive ally in the tion for a day. shape of a small poisonous black fly, under the stress of whose persecution the The conditions described by these strongest man with the firmest will must early travelers do not prevail in all either feel depressed or succumb to low parts of Alaska with equal inten- sity, nor are they always as severe ' Now with the Department of Ento- mology, Cornell University, Ithaca, N.T. in the same locality from year to ' Italic numbers in parentheses refer to year. However, Stefansson (JOl) Literature Cited, p. 81. after many years of travel and ex- AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
ploration in the North considered during 1947-48. Work in this area mosquitoes one of the principal ob- was carried on mainly during the stacles to the development of this summer and was handicapped by region. huge swanns of mosquitoes, which The first information on the spe- emerged after the spring thaw and cies of mosquitoes that are such a persisted until the first frost. Four severe pest in many places in Alaska species wei-e present. Neither fuel may have been obtained by Trevor oil alone nor fuel oil and DDT Kincaid (Coquillett i?(9) of theHar- gave satisfactory control in air- riman Alaska Expedition in 1899. plane applications against larvae, He collected large numbers of in- but DDT-fuel oil applications sects, including two species of mos- against adults markedly reduced quitoes. Mosquito collections have the mosquito population for a few also been made by J. S. Hine of the days. National Geographic's Mount Kat- The need for protective measures mai expedition in 1917, as well as against the hordes of biting insects by H. G. Dyar in 1917 and J. M. in the arctic and subarctic became Aldrich in 1921. more urgent with the increased mil- The habits, biology, and methods itary interest in these regions after of control of mosquitoes in Alaska 1941. As a result of a discussion were first investigated in the sum- of these problems by workers in the mer of 1931 in a cooperative project U.S. Department of Agriculture between the U.S. Bureau of Ento- and the office of the Surgeon Gen- mology and the U.S. Smelting and eral, U.S. Department of the Army, Mining Co. The investigations a project was outlined by the for- were carried on by Tidloch {106) mer to obtain basic information for at Fairbanks, Alaska. Fifteen insect control. This project was species were collected in the area approved by the Surgeon General during the summer. Recommenda- in 1946, and the Department of tions for control of mosquitoes af- Agriculture was designated as the fecting the men employed in gold- resjoonsible agency. Specialists dredging operations there included were assigned from the various burning of the dead vegetation to agencies concerned. Quarters and facilitate evaporation of partially subsistence for the men and all sup- covered pools, minor drainage, and plies and equipment were furnished spraying of breeding areas adja- by the military except microscopes cent to the mining operations with and a limited amount of similar diesel oil. equipment, which were provided by Additional information on the the Department of Agriculture. distribution, abundance, and species An advance party of five arrived of mosquitoes in Alaska was ob- in Alaska on May 4, 1947. In all, tained by Stage in 1943 {99). 21 persons were employed on the Chamberlin also added considerable project during 1947, and the num- infomiation to our knowledge of ber was increased to 40 during 1948. Culicidae during 1943-Í5 {99). U.S. Air Force pilots were assigned During 1956 in northeastern Alaska as needed, and 19 enlisted men were Ehrlich {9a) collected several spe- attached to the project for varying cies of mosquitoes not previously periods during the summer. In reported from beyond the tree line. 1949, 10 men carried on the work; Studies of the biology and control pilots and several enlisted men were of arctic mosquitoes were made for again assigned as needed. In 1950 the U.S. Navy installations at the party was limited to six men, in TTmiat. Alaska, by Jachowski and addition to the plane pilots and Schultz {75) and by Knight {80) four enlisted men. THE MOSQUITOES OF ALASKA
The U.S. Public Health Service, fauna, reared specimens were col- which assigned several men to the lected for taxonomic purposes, and project in 194:8-49, has since main- experiments were conducted on the tained a permanent staff of three control of mosquitoes with ground entomologists on mosquito and and aerial equipment. The effec- black fly problems in Alaska. tiveness of standard repellents The personnel carrying on these against Alaskan mosquitoes was investigations from 1947 through also determined. 1950 were principally entomolo- The effect on mosquito larvae of gists, but climatologists, botanists, DDT residues, which were left an aquatic biologist, and an equip- when larvae and adults were ment engineer were also included. sprayed in previous years, was in- The major effort was directed vestigated in 1950. Further inves- against mosquitoes, which are the tigations of the effects of the most widely dispersed and trouble- residues Avere made by entomolo- some pests in Alaska, but much time gists and other scientists from the was also devoted to black flies. offices of the Quartermaster General Most of these studies were carried and the Surgeon General, U.S. De- on in May, June, and July, but dur- partment of the Army, in 1951. ing 1948 the work on some phases This group also investigated the ef- was begun in March and continued fectiveness and acceptability of through September. clothing treated with insect repel- The work on mosquitoes was di- lents and the effectiveness of in- rected toward determining what secticidal fog-producing equipment. species were present, which were the The relationship of weather to most important as pests, where they mosquito abundance was also bred, and what could be done to- studied in Alaska by R. I. Sailer ward their control. To obtain this of the XT.S. Bureau of Entomology information, detailed biological and Plant Quarantine from 1951 to studies were made of the mosquito 1953.
Mosquito Literature
The amount of literature on mos- Matheson's handbook {86), re- quitoes has become exceedingly vised in 1944, gives much informa- large. Each year about a thousand tion on the taxonomy and biology references to various phases of the of the mosquitoes of North Amer- biology of mosquitoes and the dis- ica, and it includes a discussion of eases they carry appear in widely their relation to human welfare and scattered publications. Probably problems of control. no other group of insects has re- In 1948 Natvig {87) published ceived so much study throughout an authoritative book on the biol- the world. Some of the publica- ogy, distribution, and taxonomy of tions of especial interest to workers the Danish and Fennoscandian mos- concerned with the mosquitoes of quitoes. A number of the species Alaska are given at the end of this of northern Europe also occur in handbook. One of the early comprehensive In 1949 Bates {10) compiled books on the mosquitoes of the voluminous facts on the biol- Americas was published by Dyar ogy and disease relationships of {27) in 1928. It deals with the dis- mosquitoes. tribution, biology, and taxonomy of The taxonomy, biology, distribu- mosquitoes on these two continents. tion, and medical importance of AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
North American mosc[uitoes are methods and techniques, abatement covered in an authoritative book by of disease vectors, and a host of Carpenter and LaCasse {18), which related data. appeared in 1955. The following periodicals will be In 1959 Stone, Knight, and of interest to students of Culicidae : Starcke {]0'2a) pubhshed a synop- Mosquito News, published quarterly tic catalog on the mosquitoes of the by the American Mosquito Control world. This is a useful source of Association at Albany, N.Y., and information on the synonymy and the Proceedings, published each the world distribution of the spe- year by the New Jersey Mosquito cies found in Alaska. Extermination Association, the Cal- A textbook by Herms and Gray ifornia Mosquito Control Associa- {63) is designed primarily for en- tion, the Florida Anti-Mosquito tomologists, engineers, and staff Association, and the Utah Mosquito employees who are directing the Abatement Association. Articles activities of mosquito-abatement on mosquitoes also appear in bulle- districts. It gives information on tins and reports of the U.S. Public laws and agencies for mosquito Health Service and in various ento- abatement, education of the public, mological, medical, and other scien- general principles of abatement tific journals throughout the world.
Economic Losses Mosquito species found in Alaska vere annoyance they cause are im- are not known to cause disease, portant economic deterrents to the However, the huge numbers (fig. 1) development and progress of the present in many places and the se- State. The efficiency of all human
PN-808 FIGURE 1.—Mosquitoes resting ou a man's back—typical of the mosquito problem that in some years may affect much of Alaska during June and July. THE MOSQUITOES OF ALASKA effort in any area where large num- verse effect on wild game, occur bers are present is greatly reduced when large numbers of these pests by the necessity for "fighting them are present. Alaska, also loses off" or for using bed nets, head much of its recreational value be- nets, and other protective clothing. cause of mosquitoes, and conse- Losses in weight and milk produc- quently the tourist trade is ad- tion of livestock, as well as the ad- versely affected. Mosquito-Control Organizations Mosquito-control operations in pervisors levies a special tax to raise Alaska in recent years have been the funds required for this budget. carried on almost exclusively by the Mosquito-abatement districts in military for the protection of their many States with different types of personnel. However, agricultural laws or without laws are organized areas and many small centers of under county or city supervision or population are not included in these under the direction of county health control operations. As the State departments (see Herms and Gray develops and the population in- 63). creases, control agencies to han- In 1951 there were mosquito- dle such local problems will be control associations in New Jersey, necessary. Florida, California, Virginia, Local mosquito-control agencies Utah, and Illinois (Stage 98). are commonly called mosquito- Since then one has been formed in abatement districts. Laws have Oregon and one in the Northeast- been enacted to facilitate the organ- em States. Each of these asso- ization of such districts. These ciations holds annual meetings, laws vary considerably in the differ- and most of them publish their pro- ent States, but the most common is ceedings, which contain valuable one whereby a district may be or- contributions on mosquito biology ganized upon the petition of 5 or and control. 10 percent of the legal voters of the There is also the American Mos- area affected. After a public hear- quito Control Association, which is ing, the board of trustees of the international in scope and has over county in which the area is situated 1,200 members. It is a nonprofit decides whether in the public inter- professional association composed est a district should be formed, and of entomologists, sanitary engi- if it so determines, it fixes the neers, control officials, medical per- boundaries of the district. The dis- sonnel, and laymen, who are charged trict is governed by a board of trus- with or are interested in mosquito tees, whose members serve without control and related work. Annual pay. The board manages the af- meetings are held in various parts fairs of the district, employs per- of the United States, usually con- sonnel, and determines the annual jointly with those of the State budget. The county board of su- associations. Life History Mosquitoes have diverse breeding life in water and water only. It habits, particularly in regard to the may be in a small tin can or in a type of place they lay their eggs, vast tidal marsh. but all have one characteristic in Some species may be found in common—they live part of their several kinds of water and others AGR. HANDBOOK 18 2, U.S. DEPT. OF AGRICULTURE only in restricted areas in certain LARVAE types of breeding places. For ex- ample, Aedes ßavescens is found All mosquitoes spend their larval only in unshaded flood plains, and pupal stages in water, and whereas many of the Alaskan Aedes most of them move freely about as species are found in a considerable aquatic insects. Without water range of open and semiwooded these stages cannot survive for more breeding places. Some genera such than a few hours. The larvae of as Aedes lay their eggs on ground most species must come to the wa- that may later be flooded, whereas ter surface for air, which they ob- others such as Culex and Culiseta tain through an air tube or other lay them directly on the water appendage located at the end of the surface. "tail." The larvae shed their skins Temperatures of air and water, four times. The larval stage alkalinity or acidity of the water, usually lasts from 4 days to 2 weeks, and associated shelter and vegeta- but some Aedes mosquitoes may re- tion affect the abundance and pres- main as larvae for a month or more ence of most species. The species when the water temperature is just also differ in biting habits, longev- above freezing. ity, and flight range. The food of mosquito larvae con- The mosquito has a complete sists of microscopic plants and ani- metamorphosis. There are four mals and organic debris. Some well-defined stages—the egg; the species prey on the larvae of other larva, sometimes called wiggler ; the species, and some are cannibalistic. pupa, or tumbler; and the adult, or Barber (9) has reared larvae on imago. pure cultures of various organisms, and Hinman (6^) has suggested EGGS that materials in solution or col- The eggs may be laid singly as loidal suspension in the breeding with the anophelines, in rafts as water form a part of the larval food. with Cidex and Cidiseta, or in scat- We have reared several species of tered groups of various numbers as Aedes and Cnlex in the laboratory with Aedes. In very warm weath- on ground dog food and blood al- er the eggs of some species may bumin and also on yeast and pow- hatch within 2 or 3 days after they dered milk. are laid. However, in northern latitudes the eggs laid by Aedes in PUPAE the late summer do not hatch until flooded the following spring. If With the fourth larval molt the not flooded the first season, they pupal stage appears. The pupae may remain viable for several years move about by somersaulting. (Gjullin et al. 58). There is still Their life is short and active. An some question as to whether north- excellent account of the emergence em Aedes eggs require a certain of an adult mosquito from the pupal amount of drying and exposure to stage is given by Marshall {SJi). cold before they hatch or, as we be- lieve, a low oxygen concentration ADULTS (Gjullin et al. 61). A blood meal is considered necessary for the pro- Only the female mosquito has duction of viable eggs, but excep- mouth parts adapted for bloodsuck- tions have occurred both in the ing. While the insect is biting, it g&nws, Aedes (Hocking ö5) and Cw- injects a secretion that causes itch- hx (Wray 115). ing. THE MOSQUITOES OF ALASKA
Cvlex territans feeds only on The food of male mosquitoes con- cold-blooded animals such as snakes sists of nectars and other plant and frogs. There are no records of juices, but not blood. In the lab- Cidiseta niorsitan.s biting man. All oratory we have kept alive both the other true mosquitoes in Alaska feed on wami-blooded animals. sexes of some species for long peri- Many of these species also feed on ods on raisins, fruit juices, and plant nectars. sugar solutions.
Distribution
Despite the undisputed severity The Cook Inlet area is an extension of of the mosquito problem in Alaska, the Sitkan zone but is in many respects intermediate between that zone and the the problem is not of equal severity interior. Extremes of temperature are in all localities or in the same lo- more pronounced and annual rainfall cality from one year to another. rarely exceeds 20 inches. Black and Like all animals and plants, the white spruce are the principal forest trees, but such typical interior plants as distribution of the various mosquito larch and cattails are absent. species over an accessible area is de- The mosquito fauna of the Sitkan zone termined by the suitability of the is not greatly different from that of the environment. Where marked dif- coast of British Columbia. The pest problem in this zone tends to be local in ferences of climate and topography character. High populations may be prevail, it is to be expected that present on coastal flats and in forested some species will thrive in one part valleys, but the problem does not differ and be reduced in number or en- greatly from that encountered along the coasts of Washington and British Co- tirely absent in another. Knowl- lumbia. edge of these factors and how they (2) Aleutian.—This zone encompasses function is necessary if the mos- that part of southwestern Alaska beyond quito ¡problem is to be handled in- the tree line. It is a continuation of the Pacific mountain region and includes the telligently. islands of the Aleutian chain. Summer In discussing the relative abun- and winter temperatures are moderate dance and distribution of mosqui- and annual rainfall is relatively high, but toes in different parts of Alaska, the almost continuous cold fog and high winds during the summer prevent the it is convenient to divide the State ■growth of trees and give to the zone an into four zones, which coincide with aspect similar to that of the arctic coast. biotic provinces or Alaskan exten- However, grasses rather than typical sions of such provinces described by tundra vegetation form the prevailing ground cover ifig. 4). The biota is Dice (36) in 1943. These zones are reduced and mosquitoes appear to be ab- shown in figure 2 and are defined sent or present in very small numbers as follows: over most of this zone. (3) Htidsonian.—This zone comprises (1) Sitkan.—This zone includes that most of interior Alaska. It is bounded part of the Pacific mountain region from on the north by the Brooks Range and Cook Inlet to the southern tip of the on the south by the Coast Ranges. On Panhandle. It is a narrow strip of the west it is separated from the Bering mountainous coast (fig. 3) with numer- Sea coast by a narrow strip of tundra. ous' adjacent island.s. The mountains The zone is a continuation of the north- rise from .5,000 to 9.000 feet. Great gla- em coniferous forest that extends the ciers fall from the mountains and often full width of Canada and is drained by debouch directly into the sea. The cli- the Kuskokwim and the Yukon Rivers. mate is mild and over most of the Pan- The best agricultural land in Alaska is handle not greatly different from that of found in the Tanana Valley, which is the Puget Sound area. Rainfall is high part of the Yukon watershed. with an annual average in the extreme The climate is dry with extremes of southeast of as much as 160 inches. Sitka spruce and western hemlock pre- temperature—a long cold winter and a dominate in the forests. short hot summer. Temperatures in the 8 AGB. HANDBOOK 182, U.S. DEPT. OF AORTOULTUB^
Of EAM ALASKA t I Tundro.bor« rocK* ii I I IntfHor boreol /ortst ^^1 Cooital far«st
FiGXTKE 2.—Biotic provinces of Alaska, adapted from Dice (26), superimposed on vegetation zones, adapted from a map compiled by Sigafoos (in Hopkins et al. 70, p. 1S6).
PN-no FiGUEE 3.—Aerial view of Valdez, shovcing characteristic topography of the south- central Alaskan coast. THE MOSQUITOES OF ALASKA
PN-811 FiGUBE 4.—West coast of Kiska, showing grasses typical of the Aleutian zone. (Photograph by Ales Hrdlicka, 1936.) high 80's are not uncommon in July, and line in the Alaska Range, as well as in during midwinter the minimum readings the smaller mountain ranges of central may remain between —40° and —60° F. Alaska, are zonal subareas of the Hud- for several days. The average precipita- souian zone. So far as mosquitoes are tion is about 12 inches. concerned, it seems best to treat these In undisturbed areas much of the land tundra inclusions as extensions of the is covered with black spruce bogs, com- Eskimoan zone, although there may be monly referred to as muskeg. The for- noticeable differences in relative abun- ests are seldom high or dense, and they dance of the species present, as well as a enclose large areas of sedge (Carex) and tendency toward greater diversity of grass (usually Calamagrostis) meadows, kinds. which are marshy during part of the sum- (4 ) Eskimoan.—This zone includes the mer (fig. 5). Drainage is characteristi- area to the north and west of the Hud- cally slow, at least in part because of the sonian zone and lies beyond the tree line. permafrost throughout most of the zone. Drainage is to the Arctic Ocean and the Poor drainage and low evaporation dur- Bering Sea. Extremes of temperature ing the long winter account for the gen- are not so great as in the interior. The eral prevalence of bogs and swamps. summers are generally shorter, and cold, The mosquito problem reaches its most foggy weather is more prevalent. Rain- serious proportions in this interior zone, fall is low ; the average for much of this for though mosquitoes may be as numer- area is below 10 inches and that at ous on the arctic slope, fewer people are Point Barrow only a little more than 4. concerned. In some years troublesome The nearest approach to trees is populations may be hard to find, but dur- shrubby willows and alders, which in ing other years a pest population may some favored localities reach a height of cover thousands of square miles. ^ to 8 feet. The ground cover consists of a Following Dice's (26) definition of a thick continuous mat of heath, prostrate biotic province, areas above the timber- willows, sedges, mosses, lichens, and 10 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
Ki-asspR, find it is sonerally referrpd to Mosquitoes are perhaps more numerous as tundra ( ligs. 0 and 7). The surface is tlian in the forestod interior, tliough few- rougli, spongy, and usually waterlogged. er species are represented. Year-to-year Frozen soil is seldom more than 8 or 10 fluctuation appears to be less, probably Inches beneath the surface even in late because even poorer drainage and lower summer. evaporation tend to minimize yearly dif-
..mü
PN-812 FIGURE 5.—Tanana Valley near Nenana, showing marsh pools in the center back- ground.
PN-813 riGURE 6.—Tundra near Teller, shovring lighter areas covered with cottongrass bloom. THE MOSQUITOES OF ALASKA 11
FiGUKE 7.—Tundra 5 miles south of Kotzebue. The alder bushes in the foreground attaia a uiaxiiiiuui height of 3 feet.
ferences in rainfall. The tundra-inhab- were obviously concentrated along iting species exhibit greater tolerance the few highways and at localities to wind and low temperature than the mosquitoes of the interior. Frequently easily reached by air or river boat. it is necessary to wear a head net over These localities are so widely scat- a parka in order to work or move about tered that only the most general in- the country in relative comfort. ferences may be drawn from the These four zones reflect prevail- records. ^^Iien these maps are ing patterns of climate, which de- compared with figure 2, it is appar- termine the as.sociation of species ent that although most records for found there. Since climate is a any one species are confined to one measure of average weather condi- zone, most species have been re- tions taken over a long period of corded from two, and some from all time, it would be surprising if year- but the Aleutian zone. In general, to-year differences in weather did the distribution shows a close rela- not have a marked effect on the mos- tionship to the tree line. Actually quito population. Such an effect this relationship is closer than indi- has, in fact, been demonstrated ^ cated by the maps, which are drawn and is discussed below under Abun- at too small a scale to show many dance. islands of tundra that are included Maps 1-12 ■* show the known dis- in figure 2 and map 9 as forested, tribution in Alaska of the 27 species or to show the sinuous bands of that have been collected there. The forest that follow stream courses for records are based on studies that many miles into the typical tundra.
Abundance
Records of mosquito conditions rious proportions were present dur- at Fairbanks for 1929-31 and 1947- ing 1929, 1948, and 1919. During 53 show that pest populations of se- the remaining 7 years the mosquito problem was not materially differ- ' Unpublished data of Alaska Insect ent from that to be expected in un- Control Project. * See Api>endix, p. S7. cultivated areas of the Eastern 12 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
United States. The Fairbanks In addition, local residents of data, supplemented hy similar data Kotzebue, Teller, and Nome have coverinfi 1951 and 1953 for the cen- reported that, although trouble- tral Alaskan localities of Foi-t some mosquito populations are pres- Yukon, Nenana, and Tan ana, all ent in most years, there are summers show that each summer of unusual when few mosquitoes are seen. mosquito abundance has been pre- Presuinably the more constant ceded by a period of aljove-noiTnal year-to-year abundance of mosqui- precipitation. toes in the tundra areas of western That this is true is not surpris- and northern Alaska is the result ing, for the species of greatest pest of reduced evaporation during the importance are known to develop in short cool summers. One effect of temporary pools formed from melt- reduced water loss would be the av- ing snow and ice, and water must eraging out of unusual departures remain in these pools for tlie period from nonnal precipitation, and required for mosquito development. thereby greater uniformity of con- Under the climatic conditions of ditions favorable to mosquito de- central Alaska, snow ordinarily ac- velopment would be assured in both cumulates from October tlirough a regional and a year-to-year sense. April. At brealnip, wliich usually occurs during early May, the snow PREDICTING ABUNDANCE melts and forms innumerable pools, the duration of which is determined Ability to predict mosquito abun- by (1) the amount of accumulated dance in advance of adult emergence snow, (2) the moisture content of has definite and rather obvious ad- the soil at the time of the freezeup, vantages. Even a month's advance and (3) the rate of evaporation and information would permit improved replacement during May and June. coordination of control programs The last factor appears to be the and distribution of supplies to areas least important, for May and June of greatest need. It would also be are months of consistently low rain- advantageous if mosquito condi- fall and high evaporation. By tions could be anticipated before a contrast, the first two factors are work crew or .survey party is sent extremely variable and may com- into a remote area. Sometimes it bine to give an exaggerated effect might be desirable to plan the work or tend to cancel each other. Thus, so it would not coincide with the above-normal snowfall may thaw at season of adult activity, or the work breakup and be lost in abnoniially might be done at an alternative lo- dry soil, with the consequence that cality where no mosquito problem is few mosquitoes are produced. expected that season. Present evidence indicates that Present data ^ indicate that rea- the abundance of mosquitoes is more sonably accurate predictions of uniform from year to year at tundra mosquito abundance can be made localities than in central Alaska. for those localities in central and Umiat is known to have had a se- arctic Alaska where weather rec- vere mosquito problem each sum- ords have been maintained long mer from 1947 until 1952. Yet enough to provide reliable average there is ample evidence that pest populations are not present every ° SAILER, R. I., RéGNIER, A. V., and Mc- GUIRE, J. U. USE OF PRECIPITATION DATA year at all tundra localities, for the FOR PREDICTING MOSQUITO ABUNDANCE IN population at Umiat was not trou- ALASKA. Unpublished report of work blesome in 1953 and few mosquitoes conducted with the cooperation of the were present in 1951 at Teller, office of the Surgeon General, U.S. De- partment of the Army, and assistance where they were abundant in 1953. of the Arctic Institute of North America. THE MOSQUITOES OF ALASKA 13 annual precipitation values. Two which include the months of May years' oíjservations at three locali- througli September, and winter pe- ties in central and two localities in riods, which include the months of arctic Alaska have shown that abun- October througli the following dance of mosquitoes is correlated April. Weighted values must then with departure from normal precip- be assigned to departure from nor- itation, and that the best correlation mal precipitation for each of the is found when departure is based three summers and tliree winters. on a 36-month period preceding The scheme of weights that pro- May 1 of the season for which pre- vided the best correlation with ob- dictions are to be made. served abundance was 3-l-3-l--1^4. Presumably the 36-month precip- Figure 8 shows the results of the itation interval is necessary in order observations made at the five Alas- to account for soil-moisture condi- kan localities during the summers tions preceding the last winter's of 1951 and 1953. The counts snow accumulation. The greater shown were based on the number effect of precipitation received dur- of mosquitoes captured in eight 180- ing the immediately preceding win- degree sweeps with a 15-inch ter and summer on mosquito abun- Ward's professional insect net, four dance makes it necessary to divide sweeps taken on the lee and four the 36 months into summer periods, on the windward side of the ob-
MOSQUITO COUNTS AS RELATED TO PRECIPITATION
Economic Importance: SLIGHT LOCALIZED REGIONAL cour 1
60 «
40 1 y
20 • 1^/ • mmmm^ 1 I -I- -40 -20 0 20 40 % OF NORMAL PRECIPITATION
PN-815 FIGURE 8.—Regression of mosquito counts on departure from normal precipitation for 36 montli.s computed as six consecutive summer and winter intervals, a-ssigned weights of 3-1-3-1-4-4. Vertical sections labeled .slight, localized, and regional indicate the economic importance of mosquito populations expected to be prevalent under corresponding ranges of departure from normal precipitation. Based on data obtained in 1951 and 1953 at Xanana, Nenana, Fort Yulion, Kotzebue, and Teller. 14 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE server. Tlie first sweep was made gional economic importance (fig. at the Iniee and the fourth at shoul- 8). The regression indicates that der level. Counts were made hour- at a locality where the 36-month ly at a sheltered site and at a site weighted departure is more than exposed to the wind. Each count 30 percent deficient, men should be was preceded by a 5-minute period, able to live and work in the field during which meteorological obser- with little prospect of mosquito an- vations were made. This provided noyance. If the departure is be- a standard exposure period, during tween 30 percent deficient and 10 which mosquitoes were attracted to percent excess, complete protection the observer. At no time was a re- from mosquitoes will be required pellent used. in some localized areas. These So far as possible the observation areas will become more numerous pei'iod at each locality included 24 and larger as the departure ap- hours of optimum conditions for proaches the upper limit. Above mosquito activity. To minimize the 10 percent excess the mosquito-in- eti'ect of transient weather condi- fested areas fuse, and an evenly dis- tions on mosquito activity, the 10 tributed pest population may cover highest counts obtained at each hundreds of square miles. locality were averaged. On the Limited experience obtained from chart the average count for each lo- predictions made for several locali- cality for each year was plotted ties in the suminer of 1956 suggests against the weighted departure that an early breakup followed by from normal precipitation for that a prolonged period of above-normal locality and year. temperatures may cancel the effect Using the 3-1-3-1-4-4 scheme of of excess accumulated precipitation, weights, the precipitation depar- with the result that few mosquitoes ture equals are produced at a locality where a 3f+le+3d+lc+41)+4a severe outbreak would otherwise be 16 expected. However, it seems doubtful that a late breakup and where a equals actual departure cold spring would result in a serious from normal precipitation for the mosquito problem where a popula- immediately preceding winter and tion of little consequence had been b for the preceding summer. The expected. Data supporting this remaining letters represent the contention are lacking, but there is other preceding winter and summer no evidence of a general hatch of data in seasonal sequence to the be- Aedes eggs in pools formed as a ginning of the 36-month precipi- result of spring rains. Further- tation period. more, abnormal rainfall would be The regression line shown in fig- required to maintain such pools ure 8 was fitted to the data by the long enough for larval develop- least squares method. The shaded ment to be completed. If further area on either side of the line rep- experience confirms these views, resents the calculated 95-percent errors in prediction will generally confidence limits indicated by the be in the direction of fewer mos- available data. The regression line quitoes than expected. becomes straight when placed on a semilogarithmic scale. EFFECTS OF WEATHER ON The actual value of this effort to MOSQUITO ACTIVITY correlate mosquito abundance with precipitation will depend on how "Weather is the paramount factor accurately the correlation can be affecting adult activity, even though used to predict populations of the northeiTi mosquitoes are re- slight, localized, and serious re- markably well adapted to their rig- THE MOSQUITOES OF ALASKA 15 orous environment. Of the various never function independently, and elements of weather, temperature is their effects in combination are the most important, for during a often very subtle. The factors hav- period of 24 hours the mosquitoes ing the greatest effect are tempera- are commonly subjected to tempera- ture, light, wind, saturation defi- tures both above and below those ciency, lapse rate, and pressure at which flight activity normally change. occurs. Temperature.—Pratt [90) found With the possible exception of in his study near Fairbanks that Oulex territans, all species are most activity occurred between 45° crepuscular; however, this habit is and 80° F., with 60° approximately modified by light conditions ¡pecul- optimum. Jachowski and Schultz iar to high latitudes. Periods of {75) reported similar findings for gi'eatest activity tend to coincide the arctic species at Umiat. Unpub- with twilight, the highest peak oc- lished data ^ from Kotzebue and curring in the evening and a lower Teller show considerable activity peak in the morning. In latitudes at 42° and some at 40°. It is likely north of the Panhandle wliere there tliat factors other than temperature is no complete darkness during the suppress activity above 80°, for at mosquito season, the drop in activ- such times the sun is usually bright, ity between the peaks coincides with the saturation deficiency is high, the rapid fall in temperature that and a moderate wind may be occurs during the short period when blowing. the sun is below the horizon. Over Light.—Direct correlations of much of the area north of the Arctic activity with light are difficult, Circle the effect of temperature is because other factors such as tem- even more pronounced, although perature and saturation deficiency the sun does not set. are closely related to light. Never- During favorable weather, mos- theless, most workers have been im- quito activity on the tundra is more pressed by a daily rhythm of ac- nearly continuous than in central tivity, which may be suppressed or Alaska, building up from a low of even displaced by combinations of near zero between midnight and 2 adverse or favorable factors other a.m. to a peak between 8 and 11 p.m. than light. If other factoi-s are Periods of calm, cloudy weather constant, counts on which activ- during the day are usually accom- ity is based average highest at a panied by increased activity. However, any prolonged cloudiness light intensity approaching twi- results in lowering the tempera- light conditions. ture, which soon falls below the Wind.—In central Alaska, mos- threshold of activity. quito activity subsides abruptly at At Kotzebue and Teller, periods wind speeds above 2 miles an hour of intense activity and relative free- and drops to zero at about 5 miles dom from mosquito annoyance fol- per hour. At tundra localities the low a pattern that must be char- arctic species are not noticeably af- acteristic of the western seacoast. fected by wind at speeds below 5 This pattern is controlled by a miles per hour, but begin to disap- cyclic kind of weather, whereby 2 pear when the velocity reaches 7 or 3 warm, fair days are followed miles per hour. If other conditions by a week or more of cold, wet, are favorable, a few will persist windy days. even at a velocity of 10 miles per Although the factors affecting the activity of the adult female mos- " Report by R. I. Sailer, A. V. Régnier, quito are well established, they and J. U. McGuire. 551810 0—61 2 16 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURK hour. Wind velocities appear to Lapse rate.—Lapse rate is a meas- have an exaggerated effect when ure of rate of temperature change temperatures are near the upper from the ground level up. Pratt and lower threshold values. At low {90) found that mosquito activity temperatures this effect has been was greatest during inversion con- observed at Kotzebue and Teller, ditions when the surface tempera- where considerable activity was ob- ture was below 45° F. at the 3-foot served at 43° to 45° F., but only if level. With more extreme inversion the wind velocity was below 1 mile conditions when the temperature at per hour. Hocking et al. (GS) 5 feet was below 45° and warmer point out that at high temperatures temperatures were above head level, greater wind A'elocity increases no mosquitoes were found at body evaporation and may affect mos- level, but they were seen flying in quitoes in the same way as high the warmer air overhead. saturation deficiencies. Pressure change.—Haufe {61) in Saturation deficiency.—Numer- laboratory experiments with Aedes ous attempts, including that of aegypti (L.) found changes in at- Pratt (90), have failed to show a mospheric pressure to be an impor- clear correlation between relative tant factor in determining flight humidity and mosquito activity. activity, provided the mosquitoes Yet all who have observed mosqui- were first acclimated for 3 to 6 toes in the field agree that moisture hours to a particular level. When must play an important role. This the pressure was above 735 mm., de- discrepancy is easily explained, for creasing the pressure was more relative humidity is not a reliable stimulating to flight than increas- measure of the capacity of air to ing the pressure; whereas when it hold moisture. When Hocking et was below 735 mm., the opposite al. (68) converted their humidity was obtained. Although field data data to saturation-deficiency values, concerning the northern species of they were able to demonstrate a cor- Aedes are still lacking, failure to relation with activity. However, consider pressure change as a fac- the effect appeared to be delayed, tor may explain some discrepancies with attack figures rising shorlly in past attempts to correlate mos- after a fall in saturation deficiency quito activity with meteorological and falling shortly after a rise. data.
Biology LARVAL HABITATS The one-generation habit is com- When compared with the more mon to all species, though at An- temperate parts of the world, chorage a small second hatch of Alaska has noticeably fewer kinds several species of Aedes has been of habitats in which mosquito lar- observed during August after vae can live. Tree holes are an ex- heavy summer rains. The species ample of a missing habitat. No of greatest pest significance hatch doubt such water-containing cavi- within a few days after the spring ties exist in southeastern Alaska, breakup, or as soon as the snow or but over the rest of the State they ice has thawed from the bottom of are absent either because the trees the pools. Most of the pools are are small or because of frost action. temporary and originate from melt- With the exception of Culiseta, no ing snow. species are known to breed in arti- A practical system of classifying ficial containers. larval habitats is one based on the THE MOSQUITOES OF ALASKA 17 degree of pool permanency, for to a Sphagnmn-hft.nûi bogs commonly great extent this factor detei-mines support stands of scrubby black other pool characteristics such as spruce and form the muskeg so char- vegetation type, as well as presence acteristic of the subarctic region. and abundance of predators. Pool Except for deep potholes or ponds, types may be characterized as tem- both marshes and muskeg are porary, semipermanent, and perma- largely dry during the last part of nent. the summer. Temporary.—These pools of Few predators are found in snowmelt origin normally are dry -i temporary pools. to 5 weeks after the spring breakup Semipermanent.—These pools or (figs. 9 and 10). They are found ponds that are formed from snow- in widely different locations and melt are maintained to some extent support a \'ariety of emergent and by seepage or a high water table. covering vegetation. The most im- In normal yeare the pools are dry portant pools to the mosquito prob- for at least a short period during lem are those in Carex or Calama- July or August. Carex rostrata^ grostis marshes and in f^phagnitm- Potentilla pahtsfria, and Equisetum heath bogs. The marshes are shal- fhtviatUe are among the plants most low and vary in size from a few often associated with pools of this square yards to many acres. In cen- kind (fig. 11). On the tidal flats tral Alaska they are interspersed (fig. 12) Triglochin maritiina and throughout the spruce and birch Scirpus paludosun are indicative of forests of lowland or level country. the semipermanent condition (fig. Tlie flats along the southern coast 13 ). Such habitats are numerous in include large areas that are cov- river valleys where there are many ered with Myñca-Carex marshes. oxbow lakes.
PN-816
FIGURE 9—Temporarv pools in Myrica-Calarnngrostis marsh near Fairbanks, where Aedes intriidcns, commiinis; and punctor were collected. 18 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
FIGURE 10.—Temporary pools hidden in Calamagrostis marsh near Anchorage.
PN-818 FiGUKE 11.—Semipermanent pool near Anchorage, where Aedes excrucians and fitchii larvae were numerous. THE MOSQUITOES OF ALASKA 19 Predators are prevalent in semi- Permanent.~T\\^^Q ponds and permanent pools. Chaoborids, dy- lakes normally contain water tiscids, and Gallicorixa (Corixidae) through the summer (fig-s. 14, 15). are often present in numbers suffi- Lemna., Ranunculus, and Vtrlcu- cient to greatly reduce the popula- laria are common, and Carex aqua- tion of mosquito larvae. tilis often forms an emergent cover.
FiGUEE 12.—Eagle River Flats, a tidal marsh near Anchorage.
FIGURE 13.—Semipennanent pools on Eagle River Flats near Anchorage, vs'here Acdefi flavescens larvae were found. These pools were seldom more than 2 inches deep and nearly continuous over the marsh. 20 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
FiGUBE 14.—Permanent pond near P^alrbanks. Culi^eta alaskaensis and Aedes excrucians are the predominant species.
PN-822 FIGURE 1.5.—Permanent pond near Anchorage. Habitat of Anopheles earlei and CuJex territans. THE MOSQUITOES OF ALASKA 21 Predators are abundant. Odon- on the number of times species were ata naiads and dytiscid larvae and collected from one or more of the adults are always present in large pool types and on their relative numbers. abundance. Such an arrangement, based as it Habitat Preferences and Rela- is on relative permanency of the tive Economic Importance of pools, is unsatisfactory in several Species respects. It would be possible, and From data obtained in 1948 by sometimes desirable, to establish ad- the Alaska Insect Project, the spe- ditional divisions based on such cies have been tabulated according factors as shade, presence or absence to the kinds of pools utilized as lar- of vegetation, and kind of emergent val habitats. The percentages or covering vegetation. There is shown in table 1 are estimates based also a marked tendency for species
TABLE 1.—Species of mosquitoes arranged according to kinds of habitats from tohich larvae have been collected in central and arctic Alaska and their relative economic importance
Percentage of species collected in Relative economic im- différent kinds of pools portance ' Species Tempo- Semiperma- Perma- Central Arctic rary nent nent Alaska Alaska
Aedes intrudens- 100 canadensis ^- + + implicalus _ . 80 20 communis- _ 70 .30 punclor 70 30 hexodontus-. 60 40 impiger 60 40 diantaeus 50 50 cataphylla ^ + + pionips 40 60 nigripes ^ + ' + pullatus ^ + -t- cinereus 30 70 Stimulans 100 flavescens 100 riparius ^ excrucians 70 30 fitchii 70 30 aboriginis ^ + declicus 60 40 Culiseta alaskaensis. 80 20 impatiens 80 20 incidens ^ + + morsitans 70 30 particeps ^ Culex terrilans 60 40 Anopheles earlei 40 60
' 1 Widely distributed, a pest species during years of unusually high abundance; 2 widel'y distributed, locally troublesome, especially durmg y.*^^^^ °f "¡^„f f J^SeTv 3, restricted distribution, but abundant under certain f °l«g'f ' °°"^'t°A'A bltlman distributed, but not in large numbers; 5, widely distributed, but not known to bite man, ^' ' D'atT'absInt or too scanty to generalize. Plus marks indicate that the species has been collected in a particular pool type. 22 AGR. HANDBOOK 18 2, U.S. DEPT. OF AGRICULTURE that commonly develop in tempo- temporary pools, occurs as soon as i-ary pools in central Alaska to uti- the ice over the bottom of the pools lize semipermanent pools in areas melts. In shallow pools and in the beyond the tree line. Tlie explana- pi-esence of bi-ight sunlight this may tion of tliis plienomenon may lie liappen befoi-e the air temperature concerned with the relative scarcity has readied or passed 32° F. Sub- of predators in the tundra pools. sequent to thawing, the pools often A well-marked succession of spe- freeze solid without injury to the cies based on tlie time of peak emer- newly liatched wigglers. gence generally follows tlie order in It is a common conception that if which they are listed in tal>le 1, ice is present in a small pool, the beginning with those that develop water temperature cannot exceed entirely or mainly in temporary .39.2° F. If this were true, some pools and ending with those that species of mosquitoes Avould com- utilize semipermanent or permanent plete most of their development at pools as larval habitats. Tlie time temperatures of less than 40°. during which emergence of a spe- Through detailed studies of vertical cies may occur l^ecomes shorter to- and horizontal temperature gradi- ward tlie north or in any diiection ents, Pratt (90) was able to show toward the tree line, and species that development actually occurs at succession is more clear cut. Tlie a much higher temperature. As Culiseta species, as well as Ano- illustrated in figure 16, marked pheles earlei and Culex terrttam. temperature gradients exist within which are at or near the end of the a pool during periods of sunlight, succession, all overwinter as adults. and water in one part of this pool may be well above 50° even though Water Temperature of Larval ice i s present. Larvae were always Habitats found congregated in the warmest water. No larvae were found in Hatching of mosquito eggs, at deep pothole pools in which the least of those species developing in Avater never exceeded 40°.
PN-823 FiGUEE 16.—Diagram of a pool in which mosquito larvae are developing, showing temperature gradients during a warm, sunny day when ice is still in the pool. THE MOSQUITOES OF ALASKA 23 ADULT FOOD HABITS Females of Culex terñtans and Most discussions of mosquito CuUseta inorsitans are not known feeding habits are concerned with to bite man or other warm-blooded animals. ('. terrítans is known to the bloodsucking activities of the feed on frogs. females. Actually, plant juices Consideralile research has been and nectars must foma a pi-epon- done recently on factors that attract derance of the food consumed by female mosquitoes to a host. Hock- mosquitoes. Males are restricted to ing {06) has provided a summary such foods, and females apparently and bibliography covering this seek blood meals only as a source of work. Evidence indicates that nitrogen needed for egg production. temperature, moisture, and carbon Hocking et al. (68) presented dioxide are the principal attract- evidence that feeding on nectar is ants for the northern mosquitoes. a universal habit among females of As would be expected, these factors the arctic and subarctic species at are most effective when functioning Churchill, Manitoba. The tremen- in combination. Light colors have dous number of mosquitoes in many l)een found to be less attractive arctic or subarctic areas in contrast than dark colors to some species, to the negligible population of ver- but this order of preference is re- tebrates has roused speculation that versed for others. these species may not require a blood meal in order to produce eggs. LONGEVITY Beckel (12) obtained laboratory evidence that Aedes communis fe- The adult life span of the north- males were able to produce viable ern Aedes species is probably not eggs when fed only on sucrose more than 8 weeks in central Alaska or raisins. Furthermore, Beckel and considerably shorter beyond the could not induce communis females tree line. Very likely the longevity from the Churchill area to take a varies from year to year because of blood meal in the laboratory, nor different weather conditions. The bloodsucking activity of the females were positively identified females serves as a partial clue to longevity. observed to take blood meals in the In the Fairbanks area pest popula- field. Neither did he find evidence tions subside rather abruptly about of flight-muscle autolysis such as a nionth to 6 weeks after peak adult Hocking {67) found in specimens emergence. of morphologically similar com- In those species of Anopheles., munis. In any event, there is clear Culex, and CuUseta where the evidence that at least some of the females overwinter, it is likely that arctic Aedes species do not require many individuals have an adult life blood for egg production. Un- of at least a year. However, the doubtedly the smaller vertebrates males live only until cold weather. such as birds and their nestlings, as well as field mice and lemmings, FLIGHT RANGE form a larger source of blood than There is little information on the might be suspected. In a popula- night range of mosquitoes in Alas- tion like that studied by Hocking, ka. A large-scale test to control resort to muscle autolysis as a source mosquito larvae near Fairbanks of nitrogen may be a secondary re- (Travis et al. 10If) showed that sponse that occurs only after the adult mosquitoes penetrated to the females have failed to obtain a center of a 100-square-mile area, in blood meal within a prescribed which all larvae had been killed, time. within 3 days after they had 24 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE emerged in adjacent untreated perature near the ground to be areas. Howevei', when the same below that at which mosquitoes are area was sprayed to control adults, normally active while the air at infiltration was sufficient to require treetop level was still warm. another treatment in about 2 weeks. The periods of most intense mos- If such movement is typical of quito activity were found by Pratt untreated areas and continuous {90) to coincide with times when through a 6-week period of activity, moderate inversion conditions were such a population might disperse present. If dispersal activity is a distance of 2.5 to 50 miles. correlated with inversion condi- Several factors undoubtedly tions, it should be possible to predict affect the movement of mosquitoes. the principal direction of such One of the most important is the movements in a given area, for air habits of the different species. movement at such times usually fol- Such a species as Aedes einer eus is lows a drainage pattern determined seldom found except in vegetation by the topography. near its breeding place. In the only large-scale study undertaken MATING on the dispersal of a subarctic species, Jenkins and Hassett (77) Except for the dissenting views of released 3 million radioactive adults Nielsen and Grève {88), author- of Aedes communis. During tlie ities generally agree that mating in first week no specimens were taken mosquitoes is almost invarialjly more than 600 feet from the point associated with the swarming habit of release, and after a month only of the males. Although this habit one had been recovered from as far appears to be common to all the as 5,000 feet. Alaskan species, observations by The tundra is characterized by a Frohne and Frohne {39, 4J) and comparative absence of barriers to others show that the time and place free movement. This factor, com- of swarming may depend on the bined with the ability of Aedes species. hexodontus and nigripes to fly in The Frohnes observed swarms of wind moving at a velocity twice Aedes functor containing hundreds that tolerated by woodland species, or even thousands of males and provides ample reason to expect the noted that matings in a swarm flight range of these arctic mosqui- occurred at rates of 1 to 10 per toes to exceed that of any species minute and rarely as high as 150 found in central Alaska. per minute. They also reported The widely held view of local watching swarms of Aedes com- residents that mosquitoes are munis between 8 and 9 p.m. on June carried great distances by the wind 16, 19, 20, and 21. The swarms has never been confirmed. On the occupied the same site about 8 to 10 contrary, mosquito activity has been feet above the ground, in what was repeatedly observed to cease when- described as a "glade recess." On ever the wind velocity exceeds the June 20 at 9:30 after communis flying speed of the mosquitoes. ceased swarming, they saw a swarm Flight activity of the kind that of Aedes excrucians form at the would promote dispersal has been same site, but the focus of this observed ^ at times when the wind swarm was 10 to 20 feet above the velocity was about 1 mile an hour ground. and when a pronounced tempera- All Alaskan species for which ture inversion caused the air tem- records are available swarm in the evening except Oulex territans. It ' See footnote 3, p. 11. was observed by the Frohnes to THE MOSQUITOES OF ALASKA 25 swarm between 3:30 and 4:45 p.m. ; jected to apparently identical field however, they saw no mating. conditions.
OVIPOSITION HIBERNATION Of the various biological aspects According to Bates {10), there of Alaskan mosquitoes, perhaps are four types of season cycles least is known of their oviposition found among the life histories of habits. It is known that the Aedes mosquitoes. One of these types in- species lay their eggs in moist de- cludes all the Alaskan species of pressions, which are subject to flood- Aedes and is referred to as the A. ing at the time of the spring break- cinereus type of cycle, in which up. Eggs of the Anopheles species there is but one generation a year are laid on the surface of the water, and liibeniation is in the ^gg stage. and eggs from each deposition tend With one possible exception, the to clump together. The Cidex and remaining Alaskan species—those CuUseta species deposit rafts of belonging to Anopheles, Culex, and eggs. Frohne (34) has shown that CuUseta—belong to a fifth type of Culiseta alaskaensis and impatiens cycle recently described by Frohne females are rather discriminating in ( 3^ ) and referred to as the CuUseta their selection of oviposition sites, ¡tnpatien-'i type. In this cycle fer- alaskaensis selecting small pockets tilized females overwinter and there in emergent clumps of dead Carex is but one generation a year. and impatiens ovipositing on open Cidixeta morsitans may overwin- water devoid of emergent vegeta- ter in the larval stage and would tion. Very likely the Aedes species tlius fall in the Anopheles elaviger are also able to detect and lay their type of cycle described by Bates. eggs at sites suitable for the larval The type of season cycle must have development of their particular an important bearing on the dis- species. tribution of mosquitoes in Alaska, Eggs of some northern Aed^s for those species belonging to the species remain viable (Gjullin and C. impatiens type are rarely found Yates 57) for several years. Water beyond the tree line, except in having a low oxygen content is mountainous areas where the tree important as a hatching stimulus line is detemiined by altitude. for eggs of these species (Gjullin Probably these species require the et al. 51). Additional factors must sheltered habitats associated with also play a part, since not all eggs trees as hibernating quarters for the hatch even though they are sub- adult females. Surveys of the Mosquito Problem Adequate mosquito surveys and ments for operating funds and engineering sui-veys must be made proper execution of the control if control measures are to give satis- program. factory results quickly and econom- ically. Such surveys are often MOSQUITO SURVEYS initiated by a few interested indi- viduals who wish to leani whether Mosquito sun'eys must be made their local mosquito problem can be by competent entomologists. The alleviated or eliminated. If con- entomologist must determine what trol appears to be feasible, then species are present and learn as community action is usually re- much as possible about their biology quired in order to maie arrange- and their enviromnent. He should 26 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE establish which species contribute can be made of progress over the to the problem and whicli are un- years in each community. common or do not bite man and his Mosquito surveys normallj^ in- domestic animals. Surveys should clude the collection and identifica- extend some distance beyond the tion of both adults and larvae. In boundaries of the community for some areas outside Alaska useful wliich a control program is being information has also been obtained planned, for some species are known from egg surveys. to disperse several miles. Under Adult surveys.—Several methods Alaskan conditions surveys need not have been used to collect adult mos- be concerned with potential disease quitoes, but usually they include vectors but should concentrate on various types of hand and trap the few aggressive and abundant collections. species. Hand collections of biting mos- In order to study biting habits quitoes provide the simplest and and flight activity, the entomologist most direct method of determining must be able to identify the adult which are the troublesome species mosquitoes and also the larvae, so and the relative abundance of each. as to associate them with the type Such collections are usually made of water or breeding area in which with a killing bottle. they occur. The larvae of some The most useful procedure for species live almost exclusively in making hand collections in Alaska pennanent water and others only is to select representative locations in temporaiy water; some prefer in the community where daily, shaded pools and others only pools weekly, or biweekly collections can well exposed to the sun ; some are be made throughout the season. found in polluted water or water A normal procedure is to stand or with a large amoimt of decaying or- sit for 1 or 2 minutes at each loca- ganic matter and others only in tion and collect mosquitoes as they clear unpolluted water. alight to bite. Some standard col- Unfortunately one entire mosqui- lection time should be used, so that to season is not adequate for a com- all data can be comparable. If mos- plete entomological survey, as the quitoes are not too abundant, one species composition and abundance person can collect in a killing bottle may vary considerably from year to all those that land on the front of year. Several years are often re- his trousers. If two people are quired before the entomological working together, one can collect data are reliable. Fairly effective the mosquitoes alighting on the control operations can be started back of his companion. before the surveys are completed, Wlien two or more persons are but without reliable data, control to make collections at different may be erratic and result in the loss places, they should make some pre- of public confidence. liminary collections at one place to Mosquito surveys may provide determine the relative attractive- additional information of value to ness and dexterity of the different the control director. It is rather collectors. common for critics to maintain that Care must be taken in selecting control procedures are ineffective. the collection locations, as some If some reliable figures are available species bite more freely in the on the control of species and popu- bright sunlight and some in the lation densities, these can be used shade, and many species bite more as proof of results. There is also readily at dusk. The numbers will, a need for standard methods of of course, vary with the weather observations, so that comparisons conditions. THE MOSQUITOES OF ALASKA 27 A common hand-collecting meth- quito populations while traveling od in some areas is to catch the mos- down a road. Both of these me- quitoes in their daytime resting chanical traps have the disadvan- places, such as dark corners of tage of damaging the specimens so buildings, under structures, in hol- tliat identification may be impos- low trees, or in prepared resting sible. It may be possible to deter- places such as barrels and boxes. mine total mosquito counts but not In Alaska the resting-place collec- the species. tions are not very useful. In areas where mosquitoes swarm Traps furnish data with the least about people or domestic animals personal bias, and some types of as they do in Alaska, it is possible traps are more likely to capture to obtain a good population count rare species and males than are by making a uniform number of taken by hand collections. Traps swings with an insect net. For are not known to be of any value instance, if a net is swung back for control. They serve only as and forth quickly over a uniform a sampling device. distance and a imiform number of Several types of traps have been times, the number caught in each used. One of the most common is collection can be used as a popula- the New Jersey light trap. It has tion index figure (fig. 17). a light to attract the mosquitoes A trap that is useful to check and an electric fan to suck them in- on the total number of mosquitoes to a cyanide jar, where they are emerging from a given location and killed, or into a large cage if live on the species can be made by mosquitoes are desired. Such a placing: a cage covered with screen trap may be useful in southern Wire or mosquito netting in each oi Alaska, but it is of little value in several breeding locations to cap- the northern areas, since the nights ture the adults as they emerge. are not dark. These traps have the additional disadvantage of captur- ing many other insects. In tropical areas it is rather com- mon to use traps baited with some animal such as a horse or a mule. Such traps have not been used in Alaska, but it is thought that they would be of little value. A mechanical rotary trap has been used in Alaska with some suc- cess (Chamberlin and Lawson 19 and Stage and Chamberlin 99). It can be operated by a gasoline motor and therefore does not de- pend on electricity or darkness. Since it catches all insects that fly within its collecting range, the exact number of insects per cubic foot of atmosphere per time unit can be determined. Another me- PN-824 chanical trap used in Alaska is FIGURE 17.—Sweep-net method of ob- made by fastening a screen-wire taining a population count, showing the first of eight 180-degree sweeps cone on the fender of an automo- taken from knee to shoulder height. bile. With such a trap one can Four sweeps are made on each side take continuous samples of mos- of the observer. 28 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE Such a trap gave useful informa- populations are expressed as the tion in Alaska. number of larvae per dip or, if the Larval surveys.—The traditional larvae are not numerous, the num- way of making a mosquito survey is ber per 10 dips. to locate the larvae by sampling Larval surveys serve to determine various water accumulations with a not only the species present but, white enamel dipper (fig. 18). even more important, the compara- Some workers prefer to insert a 2- tive abundance in the various water or 3-foot-long stick in the handle. accumulations. They are used to Considerable skill is required in the show which areas should be treated use of a dipper. Some larvae, es- with larvicides and which areas pecially the Anopheles^ may be col- have no larvae or too few to justify lected best by skimming the water the expense. surface, whereas other larvae may In larval surveys, records must be be more easily captured by sub- kept of the types of water in which merging the dipper deeply and the larvae are found. In Alaska quickly. A little experience is Anopheles., Culex., and Guliseta are necessary before one can dip suc- typically associated with permanent cessfully. It is common for one water, Avhereas most of the Aedes person to collect rather consistently are typically associated with tem- more than twice as many larvae as porary water. another. With a little effort and The timing of the larval surveys experience, workers can be trained is extremely important. For in- to obtain rather uniform numbers stance, nearly all the Alaskan Aedes with their dips. Ordinarily larval eggs hatch as soon as the snow and
PN-82S FIGURE 18.—Using a dipper to collect mosquito larvae in a semipermanent pool near Ancliorage. Aedes communis and punctor larvae developed in marginal areas. Large numbers of Culiseia impatiens and alaskaensis emerged later from pools where water remained longest. THE MOSQUITOES OF ALASKA 29 ice start to thaw in the spring, and concentric screen cylinders in a wa- in central Alaska neariy all larvae ter bath (Horsfall 71) to remove have matured by the first week in the bulk of the soil from hand-col- June. Surveys made after the first lected samples. of June may show very few larvae A simple metliod to sample Aedes present, and these are more apt to mosquito eggs is to take soil samples be the less numerous Anopheles, to the laboratory and flood them Culex, or Culiseta. with water. As many eggs may Egg surveys.—Although no ^gg have a resting state known as dia- surveys have been made in Alaska, pause, they may not hatch well ex- several methods have been used to cept in the spring. study the distribution of mosquito eggs in other areas. ENGINEERING SURVEYS The different egg-laying habits necessitate different types of survey Engineering surveys are most ef- methods. AnopJieJes, Cidex, and fectively made after the entomolog- Culiseta ^gg surveys have been ical information has been assembled, made by skimming the water with or they may often be made concur- fine strainers such as bolting cloth rently. The purpose of these sur- or by straining water through veys is to ascertain from the critical topographical features of the mos- folded cheesecloth. The Culex and quito-producing areas whether con- Culiseta egg rafts can be seen float- trol can include such permanent ing on the water. Aedes egg sur- measures as water removal through veys have been made by sampling drainage or fills or whetlier tempo- the soil where the eggs are laid. rary control with insecticides is the Three types of mechanical de- only indicated method. The engi- vices have been used to sample neering survey must determine the Aedes mosquito eggs. One method extent and nature of the water uses a modified vacuum cleaner accumulations and whether the (Husbands 7^) to pick up the eggs. water is permanent or temporary. The soil and debris are then re- It can be made by a sanitary engi- moved with screens and the remain- neer or a mosquito-abatement engi- ing soil is examined for eggs under neer in cooperation with an ento- a microscope. The other two meth- mologist, or by an entomologist who ods employ a modified grain cleaner is familiar witli the engineering (GjuUin Jf9) or a series of three aspects of mosquito control.
Methods of Mosquito Control Mosquito control in the arctic and {16, 100), there is often little that subarctic regions received almost no an individual can do to obtain ade- attention prior to 1940. Although quate control. The most satisfac- the tremendous populations of mos- tory program is provided when c[uitoes were known to those who entire communities coordinate their lived or worked in Alaska, it was efforts. not until 1947 that comprehensive Since the midforties, when the studies were started by civilian and organic insecticides first came into military organizations to api^raise general use, mosquito control has the problems and to investigate the become more and more complicated practicability of controlling these but at the same time more effective. pests. Now, if control with insecticides is As mosquitoes can fly several indicated, one must decide which of miles from their breeding places several insecticides, which formula- 30 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE tions, and which of the many com- this method to be effective, the plicated pieces of equipment to use water level of the breeding area {107). must be higher than the natural A complete program for mosquito drainage systems, such as streams, control today is directed not only lakes^ and the sea. If the breeding against the larvae but also against a rea is higli enough, the ditches will the adults in and around buildings either keep the land free of water and in large areas. No satisfactory or else carry any larvae into the methods have been developed to con- natural drainage systems. In trol mosquitoes in the egg or pupal many communities road fills have stage. blocked natural drainage, and in such locations large numbers of CONTROL OF LARVAE mosquitoes may be produced. The proper use of drainage culverts Mosquitoes can usually be con- will correct the roadside water trolled most easily and cheaply accumulations. while they are in the larval stage. To be effective, ditching systems Two methods have proved useful— must be kept under annual surveil- environmental control, which is lance and must be maintained. more permanent, and control with Some ditches will need cleaning insecticides, which is temporary every year or so, lest they become U)- clogged and cause flooding that may produce more mosquitoes than in Environmental Control the unaltered breeding areas. Wherever possible, the water in Mosquito control by manipulat- which mosquito larvae are found ing water levels has proved satis- should be eliminated by drainage, factory in many areas and may be fills, and manipulation of water of value in special locations in levels {63). Drainage and fills are Alaska. A typical procedure is to undoubtedly the most certain meth- construct dams across the outlets of ods of eliminating mosquitoes, but lakes and ponds to hold the water the costs of such operations are level constantly high and thereby high. Although these methods limit the area of marshland on have been used successfully in many which eggs may be deposited. temperate and tropical areas, pros- Ditches may be dug along the im- pects for general use in Alaska are poundment margins parallel to the not promising. The usually large elevation contours to receive seep- and inaccessible breeding areas, the age and other water accumulations, permafrost, and the high water which should then be drained into tables characteristic of much of tlie the main impoundment by way of region impose severe limitations on secondary ditches. This method is control by drainage. The use of most effective if the margins of the fills is even less practical. Where impounded area are steep, so that fills are made, care should be taken there is a minimum of shallow that they do not interfere with nat- water, and also if they are free of ural drainage, and all borrow pits vegetation. should be opened to the natural An important aid to the control drains. Drainage and fills are of mosquito larvae in impounded likely to be of use only in or near waters, such as the TVA water well-populated communities. systems, has been the removal of Drainage is accomplished by dig- submerged vegetation along the ging a series of ditches to remove shore as well as within the main the water from locations where water area. Mosquito larvae do mosquito larvae are found. For not survive long in open water that THE MOSQUITOES OF ALASKA 31 is deep, free of vegetation, and ticularly in garden pools containing subject to considerable wave action. valuable aquatic plants or fish {Iß). However, tlie cost is too high to rec- Control With Insecticides ommend them for use in the exten- Wliere it is not feasible to elimi- sive mosquito-producing areas of nate mosquito-breeding places, the Alaska. Rotenone and creosote larvae may be controlled with in- have received some publicity from secticides. Although this method time to time, but it was not until is only temporary, it has a more DDT became available that control lasting effect in Alaska than in with insecticides became really fea- many areas. In warmer climates sible. Since then several other in- there may be several broods each secticides have been developed. season, each of which would require Tlie most practical ones from the treatment. In Alaska the principal standpoint of effectiveness and cost problem is created by the Aedes are TDE, BHC, lindane, toxa- mosquitoes. Since there is only one phene, heptachlor, dieldrin, mala- brood each year, a single well-timed thion, and parathion. With these, application will eliminate most of satisfactory control can be obtained the larvae for an entire season {29, with strikingly small dosages, from ^2,75, 76). 0.075 to 0.4 pound per acre, depend- Two methods of applying in- ing on the insecticide {50, 56). secticides have proved satisfactory An oil solution is one of the most in Alaska. They may be applied practical formulations of DDT either to the water for direct con- {103, J04). Concentrations of 1 to 5 percent of DDT in fuel oil No. 2, trol of the larvae or to the soil or diesel oil, or kerosene are the most snow as a prehatching or preflood widely used for ground equipment, treatment before the eggs hatch. and 20 to 25 percent prepared with Hand sprayers of the Flit-gun auxiliary solvents for air spraying. type are satisfactory for spraying A good auxiliary solvent for a 20- small puddles. Areas of an acre or percent DDT solution is a methyl- more can be treated with a 3- to 4- ated naphthalene such as Velsicol gallon compressed-air or knapsack NR-70, Solvesso No. 3, or Shell 42. sprayer. Larger areas can be The addition of 0.25 to 0.5 percent sprayed by aircraft (.?, 73). of Triton B-1956 increases their ef- Application to water.—Fuel oil fectiveness. Emulsions are also sat- No. 2 and diesel oil have been isfactory, but they are not recom- widely used to control mosquito mended where fish and wildlife larvae and are still used under some would be affected. Several emulsi- conditions. From 15 to 50 gallons fiable formulations are available. per acre usually gives good results A typical one contains 25 percent of when sprayed on the water. As DDT, 65 percent of xylene or other little as 6 gallons per acre has been solvent, and 10 percent of Triton effective when 3 to 5 percent of a X-100 or other emulsifier. The spreading agent has been added. dosage for the immediate control of Three satisfactory spreading agents larvae in Alaska is 0.05 to 0.1 pomid are sulfonated sperm oil (Nopco of DDT per acre {103, m). 1216), a phthalic glyceryl alkyl TDE, which has a low toxicity to resin (Triton B-1956), and an 18- fish, is useful in waters where fish carbon-chain complex amine are present. It may be used in the (Amine230X) {82). same fomiulations and applied at The pyrethrum larvicides devel- the same rates as DDT. oped in New Jersey have been suc- BHC and lindane usually give re- cessfully used in many regions, par- sults about equal to DDT, but oil 551810 O—61 .3 32 AGR. HANDBOOK 182, U.S. DEPT. OP AGRICULTURE
solutions are difficult to prepare and for distances of about one-half mile these insecticides are not particu- has been obtained by this method. larly useful in Alaska. The dosage An important recent development should not be more than 0.05 to 0.1 in insect control has been the use of pound of the gamma isomer per granulated insecticides {60, 108, acre, owing to the toxicity of these 110^ 111, 112). The granules are insecticides to fish. easily distributed by airplane, Toxaphene can be used either in ground equipment, or hand. They oil solution, as described for DDT, liave enough weight so that they are or in emulsion. The dosage should not so subject to wind drift as be 0.2 to 0.4 pound per acre. In sprays or dusts and will penetrate Alaska toxaphene has not given re- vegetative canopies and thus reach sults equal to DDT, and it is much mosquito breedmg areas. more toxic to fish. Heptaclilor has Prehatching treatments.—Pre- not been tested in Alaska but was hatching treatments have been suc- effective in Utah when applied in cessful in Alaska {106). The in- emulsion at 0.05 pound per acre secticides are applied to the dry or {60). Dieldrin has been used at moist ground in the late summer or about 0.1 pound per acre in oil solu- fall or on snow (fig. 19) before the tion and emulsion. Toxaphene, spring thaw {8S, 96, 116), and dieldrin, and heptachlor are two to hatching larvae are killed by the four times as toxic as DDT to mam- residues. The best results have mals and should be handled ac- been obtained in areas that are dry cordingly. in the late summer and early fall Use of most of the organic and wet only in the early spring. phosphorus compounds must be Prehatching treatments may be supervised carefully, as several of made with any of the DDT formu- them are toxic to man and animals. lations. One to two pounds per They should not be used for routine acre will give control for two or control unless resistance to DDT more seasons in all but seepage and the other common insecticides areas, where 2 pounds may be in- has been confirmed. Malathion, effective for even one season. one of the least toxic of these mate- These heavy applications should be rials, is being used in California made only in areas where there is {m, 56,102) at 0.4 to 0.5 pound per no danger to wildlife. Much acre. Parathion is likewise being lighter dosages of DDT applied as used in California and Utah {102), adulticides have been found to serve but special care must be taken in as effective prehatching treatments handling this material and it must for at least two seasons. In a 100- not be applied over inliabited areas. square-mile plot that had received The dosage is 0.075 to 0.1 pound per a total of 0.3 pound of DDT in acre, or 0.02 p.p.m. in water. Dip- three treatments in 1949, less than terex» (dimethyl 2, 2, 2-trichloro- 5 percent of the expected number of 1-hydroxyethylphosphonate) and larvae were found in 1951 {6). parathion have been added directly to water in irrigation ditches in PROTECTION AGAINST California (4<5) and Arkansas {¡¡.ß) ADULTS by means of an automatic appli- cator (^) before the water flowed The control of adult mosquitoes over pastures and fields. Control is often more expensive than the control of larvae, as the adults dis- 'The mention of proprietary products does not imply their endorsement by the perse over wider areas. Because of U.S. Department of Agriculture over sim- recent developments individuals ilar products not named. and communities may now be pro- THE MOSQUITOES OF ALASKA
PN-e26 FiGUEE m—Applying DDT dust as a prehatchlng treatment on snow at Anchorage.
vided with fairly satisfactory pro- prevent mosquito bites for several tection against adults. The two hours, the actual length of time be- primary methods used are the per- ing dependent on the person, the sonal protective measures and in- type of repellent used, the species secticide applications. of mosquito, and its abundance (2, ¿, 7). Liquid repellents may also Personal Protection be sprayed lightly on garments to Where mosquito control is not prevent mosquitoes from biting feasible or when a brood inadvert- through clothing. ently emerges in a control area, it The most effective mosquito re- may be cheaper and more practical pellent now available is diethyltol- to use such personal protective uamide (4-7, 97). It also provides measures as screens, bed nets, head protection from other common nets, and repellents. Alaskan pests such as deer flies, Screening of all windows and black flies, and punkies {Culi- doors with screen wire of 16 meshes Goides). When applied to the skin to the inch or smaller is a common or clothing (fig. 20), it lasts longer practice, and in fact a necessity in than any other material. It is safe most communities (8). Bed nets to use on the skin and clothing are necessary for campers and when applied according to instruc- people not living in screened houses, tions. However, it may cause as well as for those who work, hunt, slight irritation if it gets into the or fish outside control areas. eyes. It has desirable cosmetic Under extreme situations gloves properties; it dries quickly on the and two thicknesses of clothing skin to an almost invisible film, is provide adequate protection. not oily, and is almost odorless. When properly applied to the Diethyltoluamide is more resistant neck, face, and hands, repellents to removal by wiping and is more 34 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE {62), many sprays may contain pyrethrum, allethrin, or some of the thiocyanates. Malathion is also being used in aerosols, particularly in areas where resistance has devel- oped to the chlorinated hydrocar- bons. Perhaps the most widely known indoor space treatment other than that applied by the hand-pressure sprayer is that produced by the aerosol bomb. A few seconds' ap- plication will kill the mosquitoes in an ordinary-sized room or tent. If there is no wind, temporary re- lief can also be obtained outdoors by releasing the aerosol as one walks in swaths over the area. The directions on the container should be followed. Mist blowers and large fog ma- PiGUBE 20.—Testing stockings treated chines are used to control adult with repellents against mosquitoes at mosquitoes over large areas. Vari- Anchorage. ous smaller mobile units for pneu- matic spraying or production of persistent under sweating condi- aerosol fog have been found useful tions than other repellents. It is m,15,17,7J^,92,93). Specialized also less easily removed when the mist-producing equipment built for skin is rinsed with water. use around camps in Alaska is shown in figures 21 and 22 {113, Insecticides lU). The large aerosol machines may Before the newer organic insecti- be supplemented by smaller equip- cides became available, adult mos- ment attached to the exhaust mani- quitoes in buildings were destroyed with pyrethrum space sprays. The fold of motor vehicles {16, 22, U, effectiveness of the newer materi- 78, 92, 93). The jeep exhaust als and their low cost make it pos- aerosol is relatively simple and in- sible to utilize space sprays both expensive to build and attach to a in buildings and over large outdoor jeep. Temporary relief from mos- areas. In addition, many of these quitoes can visually be obtained newer insecticides will kill insects around campsites and other small when they are applied as residual localized areas with this equipment. treatments to surfaces where the In this unit the oil solution con- insects rest. taining the insecticide is introduced into the exhaust system, where it Space treatments.—Space treat- is broken up into aerosol particles. ments may be made with sprays or aerosols (16,59). Droplets with Five percent of DDT in diesel oil diameters up to 40 microns have is commonly used. been classed as aerosols and those The exhaust aerosol, which was with diameters ranging from this developed by the National Research size to 400 microns have been con- Council {86), has been modified by sidered to be sprays. In addition Jones and Holten {78) to reduce to the newer organic materials such the back pressure on the engine and as DDT, methoxychlor, and lindane increase the atomization of the THE MOSQUITOES OF ALASKA 35
'^tsrJSÄ
FIGURE 21.—Wenpel trailer equipped with compressor and insecticide tank, releasing aerosol for protection of personnel at Umiat. (Photograph by Charles Wilson.)
FIGURE 22.—Small encampment on arctic slope protected by a series of aerosol- producing units consisting of fruit-jar insecticide containers and nozzles attached at intervals to a compressed-air line. (Photograph by Charles Wilson.) 36 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE insecticide solution. Tlie modified One piece li/4" black pipe 2%" long, threaded one end unit is also easier to clean. The One 11/4" black pipe coupling jeep should be operated at a speed In addition to these materials for the of about 5 miles per hour in com- venturi unit itself, the following are pound low gear for most efficient needed for completing the installation on the jeep : aerosol production. The following 4%' of Vi" id. copper tubing for feed illustrations and instructions for line fabrication and installation of this Four brass %" pipe to %" tubing unit are given with pennission of connections One 114" black pipe nipple 10" long the authors: threaded both ends Commercial bids for the manufacture One 1%" black pipe tee of one of the units were about $.30.00, One brass 14" globe valve while the cost to construct the unit in One storage tank our shop was about $6.00 for labor and The measurements [fig. 23] of this unit $5.00 for materials, a total of $11.00. are the same as those given in the Na- The list of materials required is as tional Defense Research Committee re- follows : port ( 1945 ) except for the following : One Vs" black pipe tee 1. The throat of the venturi was One Vs ' ' black pipe plug increased from %6" i-d. to %" i.d. to One brass 14 " PiP« to 14 " tubing eliminate excess back pressure. Meas- connection ured back pressure was obtained at any One piece %" copper tubing 5" long engine speed which would allow eflScient 1/8" pipe plug
1/4" I.D. copper tubing from insecticide tank 1/8" pipe tee reamed connects here and tapped at feed and jet end to 1/4" 1 1/4" I.D. pipe coupling 1/4" I.D. pipe nipple 3" long
1/4" pipe to 1/4" tubing connector 1/4" I.D. pipe nipple threaded only one end 2" long
1/4" I.D. copper tubing to be cut off to discharge Jeep exhaust venturi insecticide at start of -Aerosol- venturi throat Open end of pipe coupling is connected to 10" long 1 1/4" pipe nipple ex- tension from 1 1/4" tee brazed in exhaust pipe 4" below manifold. Black areas at joints indicate brazing. All threaded joints coated with oil- graphite irtixture so unit may be easily disassembled for cleaning.
Threaded pipe section brazed on for capping purposes
PN-8S0 FIGURE 23.—Diagram of a jeep exhaust venturi aerosol. (From Jones and Holten 78.) THE MOSQUITOES OF ALASKA 37
above the venturi throat. The tank is normally placed in the rear of the jeep above the fender well. In operation [fig. 24, ß], the unit may be controlled to produce a dry fog (aerosol) or a wet fog (mist) by the gravity feed line control valve which controls the volume of insecticide intro- duced into the venturi. The jeep exhaust pipe is plugged with a I14" pipe plug when the venturi is in operation. A IVi" i.d. pipe coupling is brazed onto the exhaust pipe to take this plug. When the venturi is not in use, it is capped with a %" pipe cap, and the exhaust pipe unplugged. Although the aerosol treatments can reduce mosquito annoyance in urban or rural communities, the effect of a single treatment seldom lasts more than a few hours. The length of time will depend on the area treated and the abundance and flight habits of the mosquitoes, and best results will always be obtained FIGURE 24.—Jeep exhaust venturi aerosol : when the applications are made by A, Closeup view of mounted unit; B, experienced operators. unit in operation. Airplane applications of DDT spray (fig. 25) {I4.) have proved operation of the exhaust venturi gen- erator. the most economical method of con- 2. The single-size tube assembly used trolling adult mosquitoes in or near [fig. 24, A] was substituted for the the larger urban centers of Alaska. original curved two-size jet tube so that The formulation most often used it could be dismantled and reamed free of carbon with a minimum of tools and time. contains 20 percent of DDT in fuel 3. The fixed mounting in lieu of the oil with at least 20 percent of an flexible mounting permits constant avail- auxiliary solvent. The dosage is ability and ease of operation. The con- 0.1 to 0.2 pound of DDT or 1/2 to 1 trol valve on the driver's side of the jeep allows one man to both drive and pint of spray per acre. operate the venturi. "Wliere mosquitoes have become The convergent and divergent sections resistant to DDT, other insecticides of the venturi can most satisfactorily are being used, such as lindane, be formed on a mandrel turned to proper size. chlordane, aldrin, and dieldrin, When installing the unit, the exhaust which are especially toxic to fish. pipe of the vehicle is cut four inches No insecticide sprays should be used below the manifold and a section of the exhaust pipe long enough to allow the over large bodies of water where insertion of a tee joint is removed. A they are hazardous to fish. All air- IM" black pipe tee is then brazed into craft spraying should be directed by this opening. A IVi" pipe nipple 10" long extends from the tee joint and the specialists and trained pilots. venturi unit is screwed onto this exten- Residual sprays.—Many of the sion. Black pipe is used rather than organic insecticides, including galvanized for ease of brazing parts. An oil and graphite mixture is used to DJDT, will remain effective for coat all threaded joints so that they may several months when applied to be broken easily even after heating, when the interior surface of buildings the unit must be dismantled for clean- and for a week or more when ing. The supply tank may be of any applied to the exterior of buildings size, shape, and capacity, but should be placed so that it is at least 18" to 24" or to vegetation. Mosquitoes that 38 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
FiGüEE 25.—Spraying near Fairbanks with one-half pint of 20-percent DDT per acre. Picture taken at midnight.
rest on the treated surfaces will be the Cascade Range of Oregon for killed by the residues. 10 to 45 days witli residual treat- DDT residual sprays for use on ments of DDT at 2 to 6 pounds per buildings should contain 5 percent acre on plots larger than one-Iialf of DDT either in oil solution or in acre. Lindane at 3 pounds per acre emulsion. The best results are ob- gave control equal to that obtained tained if all the walls and ceilings with 4 pounds of DDT [69). In are treated. The rate of api^lication order to avoid damage to vegeta- should be about 1 gallon per 1,000 tion, wettable powders or oil emul- square feet. If the surface is not sions should be used rather than oil particularly absorptive, reapplica- solutions. tion may be necessary. In Alaska Insecticides are poisonous. an application at the beginning of When handling or mixing concen- each mosquito season should be trated insecticides, avoid spilling adequate. them on the skin and keep them Annoyance around buildings can out of the eyes, nose, and mouth. be further reduced by spraying all If any is spilled on the skin, wash vegetation to a height of about 10 feet (iJ). The wider the treated it off immediately. If any is band, the better the results, for the spilled on the clothing, change it mosquitoes will not be killed until immediately. Try to keep the they rest on the sprayed vegetation. spray away from the eyes, nose, During periods of flight activity and mouth when it is being ap- sucli treatments may provide poor plied. Wash exposed skin sur- protection, since infiltrating mos- faces with soap and water and quitoes may cause considerable an- change the clothing after using noyance before they are killed. insecticides. Follow the precau- Good control of the Aedes species tions on the container labels. common in Alaska was obtained in The extremely poisonous organic THE MOSQUITOES OF ALASKA 39 phosphorus insecticides such as resistance to DDT and other chlor- parathion and methyl parathion inated hydrocarljon insecticides. should be handled only by a per- Organic phosphorus insecticides son who is thoroughly familiar have given control \\\ tliese commu- with their hazards. nities {J^% 63). Parathion has been efl'ective in one such area for 8 years, CONTROL OF RESISTANT but partial resistance to malathion MOSQUITOES has developed in a similar area in Resistance to insecticides has California {62) after 21/^ years. In developed in many insects in many Alaska resistance is expected to de- parts of the world. In some com- velop very slowly, because only one munities in California (5J^), generation is produced annually by Florida {25, 79), and Oregon (28), the Aedes species, wliicli comprise mosquitoes have developed a high the major pests.
Technique for Mosquito Collection and Survey
Specimens that are to be pre- B) with liquid to prevent sloshing pared for study in the laboratory and consequent damage to the lar- or that are to be preserved for a ref- vae. Handle the larvae carefully, as erence collection must receive spe- the spines and hairs necessary for cial attention if they are to serve identification are easily broken off. their purpose. Specimens retain their shape better Larvae and pupae.—A white en- if killed in hot water (lOO^-lSO" amel dipper with a smooth stick F. ) and then transferred to alcohol. about 3 feet long inserted in the A i-ounce jar or larger (fig. 26, D) handle (fig. 26, A) is best for col- may be used for carrying live lar- lecting larvae and pupae. Remove vae. Injury to larvae will be them from the dipper with an eye avoided if the jar is filled to the dropper or pipette (fig. 26, 0). brim with water. As the tip of an ordinary eye To make permanent prepara- dropper is too small for sucking tions of larvae or larval and pupal in full-grown mosquito larvae and skins, remove them from the alco- the pupae, break it off to enlarge hol in which they have been pre- the opening. served and mount them on micro- The larvae and pupae can be scope slides. The larval mounts are reared in the laboratory. Since in more satisfactory if the larvae are general only the mature larvae then punctured with a needle. (fourth instar) can be identified, Place the punctured larvae or skins rear the young larvae to the fourth in Cellosolve for a few minutes instar. A careful worker will rear and then in a drop of balsam or the larvae individually and will euparal on a slide, orient them, and save the larval and pupal skins so cover with a glass coverslip. The that they can be associated with the abdomen may be cut before the balsam is applied, so that the anal adults. In the field, preserve the larvae segment and siphon can be turned in 70- to 80-percent alcohol. Pre- on the side. Such specimens, if vent undue dilution of the alcohol carefully prepared, will last in- with water; as a precautionary definitely. measure change the alcohol after a Adults.—ThB most useful speci- few hours. Fill the vials (fig. 26, mens of adult mosquitoes are pre- AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
PN-833 FIGURE 26.—Mosquito-collecting equipment: A, Dipper; B, vial; C, wide-mouthed pipette ; D, jar for carrying live larvae ; E, killing bottle ; F, paper funnel ; G, live tube; H, aspirator, straight-tube type; /, lantern chimney cage; J, pill boxes; K and L, aspirator, showing construction details. THE MOSQUITOES OF ALASKA 41 pared as soon as they are killed or After collecting a few specimens collected. Do not kill those reared in the killing bottle, transfer them in the laboratory for 24 hours after to a small container sucli as a paste- they emerge as adults to allow board pill box. The pill box (fig. them time to harden. 26, J) should contain two pieces The most useful killing bottle of soft tissue paper between two (fig. 26, E) is a chloroform tube. layers of cotton. Place the mos- Fill a strong glass tube to tlie deptli quitoes between tlie layers of tissue. of about one-half inch with cut Witliout the tissue paper the tarsal rubber bands or other small pieces claws may cling to the strands of of rubber. Pour in enough chloro- cotton and may be broken. Handle form to cover the rubber pieces and the specimens carefully, as scales close the tube tightly with a cork. and hairs that are important for When the chloroform has been ab- identification are easily rubbed off. sorbed by the rubber, tamp in a plug In the field, pin the best specimens of cotton. On top of the cotton as tliey are caught. place several disks of blotting paper Mosquitoes may be kept alive in cut to fit the tube tightly. Such a large-diameter glass tube or a vial a bottle should last several days be- open at both ends (fig. 26, G). fore it needs recharging with chlo- Cover the top with bobbinet and roform, provided it is kept tightly insert in tlie bottom a cork, in which corked when not in use. Plac« a a capillary tube is inserted for fur- few strips of soft paper, i/^ to 14 nishing water. Place a freshly cut inch wide, in the tube to prevent the raisin or wad of cotton saturated with sweetened water on top of the mosquitoes from being unduly bobbinet for food. A glass lantern rubbed. To increase the number of chimney (fig. 26, /) may be simi- mosquitoes that can be caught, place larly equipped as a container for a short paper funnel (fig. 26, F) in a large number of adults. Gener- the mouth of the killing bottle. ally one end is covered with a This funnel acts as a barrier to pre- sheet of tliin rubber. A i/2-inch vent the escape of the specimens be- slit in the rubber permits the col- fore they are killed and to reduce lector to add adults to the container the loss of chloroform fumes. with an aspirator (fig. 26, H). Another hand-collection device, is Adults that are to be retained a suction tube, or aspirator (fig. 26, in ijemianent collections are best Z), made out of a glass or clear mounted on a minuten pin stuck in- to a small square piece of cork, plastic tube about three-fourths through which is passed a larger inch in diameter and 5 to 6 inches pin. Thrust the tip of the minuten long. Intake and outlet tubes in- pin through the underside of the serted through the rubber stopper thorax of the mosquito, but not far should be copper, as glass tubes are enough to protmde through the too easily broken. Fasten bolting mesonotum. The No. 3 entomolog- cloth or fine mesh copper screening ical pin is generally the best size over the inside aperture to the out- for holding the cork. let tube. Mosquitoes can then be Label the mounted specimens sucked into the aspirator tube and carefully and pin them in a tight blown into the killing bottle. An- insect box. Protect the stored other type of aspirator, as shown in specimens from insect pests and figure 26, K, is better for handling dampness. Place ñake naphthalene adults that are to be transferred to or paradichlorobenzene in a per- a live jar, or lantern chimney cage forated container and fasten the (fig. 26,7). container securely in one corner of 42 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
the insect box to prevent damage rately identified. Mounts of the from insect intruders. Renew these male genitalia for study purposes repellents occasionally. may be made as described for mos- Älany of the northern Aedes mos- quito larvae. The genitalia should quitoes are difficult to identify, and first be cleared in potassium often only the males can be accu- hydroxide. Identification of Species The principal characters distin- fications. After some experience guishing the different species are one will be able to identify some of the shape, size, coloration, and the species with a hand lens or even scaling of the different body parts. with the naked eye. A binocular dissecting microscope Misidentification of mosquitoes with magnifications up to about may cause serious confusion. A 85 X is necessary for satisfactory few specimens that have been cor- examination. For examining lar- rectly identified will be helpful for val parts and slide mounts of male comparison. If in doubt about the terminalia, a compound micro- scope with a magnification up to identity of specimens, send them to ■iOOX is necessary. A bright spot- a specialist with the request that light is required when high magni- they be named and returned. They fications are used. may be identified if sent to the En- In the field a good hand lens with tomology Research Division or to a magnification of 10 or 15 X is some of the State universities and satisfactory for provisional identi- agricultural experiment stations. Keys and Notes for Identification The 27 species of mosquitoes Alaska. The spines on the anal found in Alaska belong to 4 genera. plate described by Frolme {35) Keys for their determination are have sometimes been utilized in the based on characters given in the larval keys. Only the more impor- literature and on others that have tant taxonomic data for each been added. The characters used species are included here, and only by Vockeroth {109) and by Beckel synonyms of recent date are given. [11) in keys to females present in The characters used for identifying Canada have been particularly use- the Aedes species are shown in ful in separating species found in figures 27 to 32.
COiTAL CELL •uaCoaTAL CELL
FIGURE 27.—Wing of Aeáes mosquito, illustrating venation (modified from Boss and Roberts 95). H-v, humeral cross vein ; C, costa ; Se, subcosta ; Pi, petiole of vein 2 ; 1, 2.1, 2.2, 3, 4.1, 4.2, 5.1, 5.2, and 6, longitudinal veins and their branches. THE MOSQUITOES OF ALASKA 43
Scutellum
occiput
FIGURE 28.—Lateral view of mosquito head and thorax, hs, hypostigial spot of scales and pcs, postcoxal scale patch. Sclerites of thorax : 1, Anterior pronotum ; 2, pro- episternum ; 3, postpronotum ; 4, mesanepisternum ; 5, prealar area ; 6, sterno- pleuron ; 7, mesepimeron : 8, nietanepistemum ; 9, metasternum ; 10, metepimeron ; 11, postnotum : 12, meron. Setae: apn, anterior pronotal ; ps, proepisternal ; ppn, postpronotal ; sp, spiracular ; psp, postspiracular ; pa, prealar; stp, sternopleural ; utne, upper mesepimeral ; Une, lower mesepimeral.
FIGURE 29.—Male genitalia of Aedes, dor- sal view, showing parts : SP, sidepiece ; Sc, scale; BL, basal lobe; Mes, meso- some; L9, lobe of ninth tergite; 9T, ninth tergite ; S, spine of clasper ; CL, clasper ; AL, apical lobe ; F, filament of claspette; Clsp, claspette; IOS, tenth sternite ; P, paramere ; BP, basal plate. 44 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
FIGURE 30.—A, Aedes impUeatus, side of thorax showing scaling; B, Aedes communis, same.
ANTENNAL TUFT H£AD HAIRS LOWER. \ANTEANTENNAL UPPER. TUFT HEAD
THORAX
ABDOMEN
LATERAL COMB OF 8TH SEGMENT PMM
FIGURE 31.—Ventral view of thorax of ANAL GILLS Aedes. OC, occiput; APN, anterior DORSAL TUFT- VENTRAL TUFT pronotum ; PPN, posterior pronotum ; PB8, probasisternum ; 8PB, sterno- PN-83e pleural bridge ; PMM, postmetasternal FIGURE 32.—Larval characters used in membrane. identifying mosquito larvae of Alaska.
KEYS TO GENERA Adults 1. Scutellum trilobed with marginal setae on lobes onh'; palpi in females much shorter than proboscis 2 Scutellum crescent shaped with marginal setae evenly distributed; palpi of males and females almost as long as proboscis.. Anopheles {earlei, p. 77) 2. Postspiracular bristles present Aedes Postspiracular bristles absent 3 3. Spiracular bristles present Culiseta Spiracular bristles absent Culex {territans, p. 79) THE MOSQUITOES OF ALASKA 45 Larvae
1. Eighthsegment without dorsal siphon or respiratory tube,. Anopheles (earlei p 77) Eighth segment with elongated siphon or respiratory tube.,. 2 2. Air tube with siphonal tufts at base " " Culiseta Air tube with tufts near or beyond middle ' 3 3. Air tube with two or more pairs of tufts extending to end of" tube ,. . , -^u 1 . , , Cidex (territans, p. 79) Air tube with only one pair of tufts Aedes
GENUS AEDES MEIGEN
KEYS TO SPECIESi Adults 1. Tarsal segments ringed with white 2 Tarsal segments not ringed with white "." 7 2. Tarsi with white rings at both ends of segments canadensis, p. 48 Tarsi with white rings at base of segments only 3 3. Abdomen with dull-yellow scales and irregular dark-scaled areas or completely yellow scaled; tarsal claw as in figure 50, B flavescens, p. 58 Abdomen dark scaled with white or gray dorsal bands 4 4. Tarsal claw large, sharply bent, and nearly parallel to long tooth (fig. 46, B) excrucians, p. 55 Tarsal claw smaller, not sharply bent, and not parallel to shorter tooth 5 5. Mesepimeral bristles absent; tarsal claw as in figure 66, B riparius, p. 68 Mesepimeral bristles usually present; tarsal claw as in figure 48, ß__ 6 6. Lower mesepimeral bristles three or more; torus with or without scales on dorsal half Stimulans, p. 69 Lower mesepimeral bristles none to four but rarely more than two; torus with white scales on dorsal half fitchii, p. 56 7. Abdomen without basal white bands or with some narrow or incom- plete ones 8 Abdomen with basal white bands 10 8. Mesonotum reddish brown; fore coxae with central area of brown scales cinereus, p. 50 Mesonotum with narrow median brown stripes; fore coxae with white scales only 9 9. Sternopleuron with 5 to 10 setae, of which a vertical line of one to four is just anterior to lower edge of mesepimeron; torus with integument dark brown or black dedicus, p. 53 Sternopleuron with 12 to 20 setae, of which a patch of 7 to 12 is anterior to and below lower edge of mesepimeron; torus with integument of outer side yellow to light brown diantaeus, p. 54 10. Postcoxal scales present 11 Postcoxal scales absent 18 11. Postpronotum with setae scattered over posterior half 12 Postpronotum with setae in single or irregular double row along posterior margin 13 12. Tarsal claws sharply bent with slender tooth nearly parallel and one- half length of claw (fig. 53, B) impiger, p. 60 Tarsal claw elongate with blunt tooth not parallel with claw (fig. 59, B) nigripes, p. 64 13. Posterior part of probasisternum with many white scales -. 14 Posterior part of probasisternum without or rarely with few white opo Ipe J-" 14. Mesonotum yellow or rarely gray with dark-brown stripes narrowed at back and extending to scutellum piomps, p. 65 Mesonotum brown or occasionally with faint dark markings ,, . , hexodontus ("tundra variety), p. 59 15. Sternopleuron with scales extending to frontal border 16 Sternopleuron with scales not extending to frontal border 17 46 AGB. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
16. Mesonotum yellowish to light golden brown with dark-brown lines punclor, p. 67; aboriginis, p. 47 Mesonotum brown or occasionally with faint dark markings punctor ("tundra" variety), p. 67 17. Wings with scattered line of white scales extending from base of costa to humeral cross vein cataphylla, p. 49 Wings dark scaled or with patch of white scales at base of costa implicatus," p. 61 18. Sternopleuron with scales extending to frontal border communis, p. 51 Sternopleuron with scales not extending to frontal border 19 19. Mesonotum yellowish brown with median brown stripes; wings with pale scales extending from base of costa to humeral vein puUatus, p. 66 Mesonotum bronzy brown with gray scales around margins and rarely with darker markings centrally; wings dark scaled or with small patch of pale scales at base of costa intrudens, p. 62 Larvae 1. Pectén of air tube with one or more of distal teeth more widely spaced 2 Pectén teeth of air tube equally spaced 10 2. Anal segment ringed by plate nigripes, p. 64 Anal segment not ringed by plate 3 .3. Hair tuft of air tube distinctly basal of last pectén tooth cataphylla, p. 49 Hair tuft >-f air tube even with or distad of last pectén tooth 4 4. Antennae longer than head diantaeus, p. 54 Antennae shorter than head 5 5. Apical setae of lateral valves (i.e., triangular flaps at apex of tube) hook shaped, as long as longest pectén tooth excrucians, p. 55 Apical setae of air-tube valves barely discernible, not longer than shortest pectén tooth 6 6. Upper and lower head hairs single or double 7 Upper head hairs three or more branched, lower two or more branched 8 7. Antennae not longer than anal segment riparius, p. 6S Antennae at least one-fourth longer than anal segment decticus, p. 53 8. Upper head hairs two or three, lower double flavescens (in part), p. 58 Upper head hairs usually four or more, lower two or three 9 9. Tuft of air tube with five to seven hairs intrudens, p. 62 Tuft of air tube with two or three hairs cinereus, p. 50 10. Anal segment ringed by plate or very narrowly open ventrally 11 Anal segment not ringed by plate, broad opening ventrally 12 11. Comb of eighth segment a row of 5 to 9 or rarelv 10 scales; anal plate closed ' hexodontus, p. 59 Comb of 10 to 19 scales; anal segment narrowh' open or closed punctor, p. 67 12. Both pairs of head hairs single or occasionally with one or two hairs double 13 Both pairs of head hairs not single and at least one pair multiple 15 13. Comb on eighth segment of 40 or more scales communis, p. 51 Comb on eighth segment of less than 30 scales 14 14. Comb on eighth segment of 8 to 16 thornlike scales, lateraî spinales less than half as long as apical spine impiger, p. 60 Comb of 15 to 25 blunt scales, lateral spinules nearly as long as apical spine implicatus,p.%\ 15. Apical setae of air-tube valves hook shaped and as long as lateral valve , fitchii, p. 56 Apical setae of air-tube valves inconspicuous, not so long as lateral valve 16 16. Air tube with pectén teeth on basal one-third or occasionally slightly farther; anal gills usually twice length of anal segment; (spines on apex of anal plate long and slender, fig. 63) pullatus, p. 66 Air tube with pectén extending nearly one-half length of tube; anal gills seldom twice length of anal segment 17 17. Comb on eighth segment with 60 or more scales; air tube about 2U X 1 (spines on apex of anal plate short and slender, fig. 61). pionips, p. 65 Comb on eighth segment with less than 40 scales; air tube about 3 X 1 18
' About 10 percent of the females of this species have a few scales extending to the frontal border of the sternopleuron. THE MOSQUITOES OF ALASKA 47
18. Comb scales thornlike; apical spine more than twice as long as any lateral spinule flavescens (in part), p. 58 Comb scales acute apically but not thornlike; apical spine less than twice as long as lateral spinules ig 19. Upper head hairs si.x to seven, lower four to five 'canadensis p 48 Upper head hairs three to four, lower two to four ' 20 20. Anal segment longer than wide; mesothoracic hair Ño. 1 double or triple Stimulans p 69 Anal segment about as long as wide; mesothoracic hair Ño. 1 single ' aboriginis, p. 47 Male Genitalia 1. Glasper inserted before apex of sidepiece; unequally bifurcate at base cinereus, p. 50 Clasper not inserted before apex of sidepiece; not branched at base. 2 2. Basal lobe without spines 3 Basal lobe with spines 5 3. Filament of claspette narrow and of approximately equal width, canadensis, p. 48 Filament of claspette expanded along one margin 4 4. Filament of claspette with one side roundly expanded at base___ nigripes, p. 64 Filament of claspette with one side expanded to sharp point at base excrucians, p. 55 5. Basal lobe with one spine 6 Basal lobe with two or more spines 14 6. Apical lobe with short appressed setae aboriginis, p. 47; hexodontus, p. 59; punctor, p. 67 Apical lobe with long hairs or nearly bare 7 7. Basal lobe extending almost to apical lobe flavescens, p. 58 Basal lobe a small area at base of sidepiece 8 8. Apical lobe of sidepiece nearly bare 9 Apical lobe distinctly setose 10 9. Filament of claspette expanded into sharp projection near base implicatus, p. 61 Filament of claspette expanded in gradual curve near base caiaphylla, p. 49 10. Filament of claspette sickle shaped with small notch at base fitchii, p. 56 Filament of claspette not notched at base 11 11. Basal lobe rounded 12 Basal lobe cone shaped or wedge shaped 13 12. Filament of claspette expanded to its maximum width at base commiinis,^" p. 51; pionips, p. 65 Filament of claspette expanded to its maximum width near middle Stimulans, p. 69 13. Basal lobe projecting in cone shape at right angles to sidepiece. _ riparius, p. 68 Basal lobe evenly sloped to its maximum width at basal edge impiger, p. 60 14. Apical lobe with dense tuft of long hairs 15 Apical lobe without tuft of hairs 16 15. Apical lobe conical, well developed; claspette stem with sharp angle near apex diantaeus, p. 54 Apical lobe flattened, oval; claspette stem with rounded shoulder near apex decticus, p. 53 16. Claspette with sharp angular projection ending in stout setae at middle inirudens, p. 62 Claspette with rounded angle at middle pullatus, p. 66
'»Postcoxal scale patch present on male pionips and absent on communis.
Aedes aboriginis Dyar row along posterior margin. Post- Aeäes aboriginis Dyar, Insecutor Insci- coxal scales present. Sterno- tiae Menstruas 5: 99. 1917. pleuron with scales extending to Female.-Mesonotum yellowish frontal border. Scutelhim with to light golden brown with paired jeHow or bronzy bristles. Pro- dark brown stripes and posterior basisternum without white scales on half lines. Postpronotum with posterior part. Lower mesepimeral setae in single or irregular double bristles one or two. Abdomen black 551&10 0—61 4 48 AGR. HANDBOOK 18 2, U.S. DEPT. OF AGRICULTURE with basal white bands widening at sides. Wings dark scaled in about 95 percent of specimens. Legs black. Male genitalia, (fig. 33).—Side- pieces three times as long as broad; apical lobe long and rounded with short curved setae ; basal lobe flatly conical with numerous setae and long curving spine near base. Clas- pette pilose, slightly curved, and expanded near middle; filament shorter than stem, slightly ex- panded at middle, and terminating in blunt curved point. Larva.—Antennae sparsely spined. Head hairs, upper usually three to four and lower two to four. PN-841 Mesothoracic hair No. 1 single. La- FIGURE 34.—Aedes canadensis male teral abdominal hairs one to two genitalia. long hairs. Comb on eighth seg- ment with about 30 scales in patch. as wide, anal plate extending to Air tube about 3X1; pectén fine near ventral line; anal gills pointed and even and not reachmg middle, and longer than segment. followed by four to six large hairs ; Bionomics.—This species has apical setae not so long as lateral been recorded from several locali- valve. Anal segment about as long ties in the Panhandle (map 9). Larvae were collected in May, June, and July in roadside borrow pits that were devoid of vegetation (Frohne and Sleeper 4^). Nothing further is known of the species' habits or behavior in Alaska.
Aedes canadensis (Theobald) Culex canadensis Theobald, Monog. of Culicidae of World, v. 2, p. 3. 1901. Female.—Mesonotum reddish brown with pale-yellow scales around margins. Abdomen black without basal white bands or with narrow indistinct ones; sides with triangular white spots. Wing scales all dark. Legs black; hind and midtarsal segments apically and basally w^hite banded; fore tarsus banded on first and second segments ; last segment of hind leg entirely white scaled. Male genitalia (fig. 34).—Side- pieces slightly more than twice as long as wide; apical lobe large, FIGURE 33.—Aedes aboriginis male geni- low, and broadly rounded with short talia. bladelike setae; basal lobe long, THE MOSQUITOES OF ALASKA 49 surveyed by the Alaska Insect Con- trol Project in 1947 and studied in- tensively during the entire spring and summer of 1948. It is hardly conceivable that such an easily rec- ognized species could have been missed ; more likely this is further evidence of the year-to-year insta- bility of the mosquito population in centralAlaska. No larvae have been collected in Alaska. In the United States and Canada larvae develop in temporary or semipei'manent, shaded, woodland pools containing fallen leaves.
Aedes cataphylla Dyar Aedes cataphylla Dyar, Insecutor Insci- tiae Menstruus 4 : 86. 1916. Female.—M esonotum gray PN-842 around sides with golden-brown FiGUEE 35.—Aedes canadensis larva. scales in middle, which sometimes show faint dark lines. Postprono- with many short setae. Claspette tiuTi with setae in single or irregular cylindrical and setose, larger seta double row along posterior margin. before apex; filament narrow, lin- Postcoxal scales present. Stemo- ear, pointed, and slightly shorter pleuron with scales not extending to than stem. frontal border. Probasisternum Larva (fig. 35).—Antennae spi- without white scales on posterior nöse. Upper head hairs six to part. Lower mesepimeral bristles seven, lower four to five. Lateral two to seven. Hypostigial spot of abdomen hairs usually double on scales usually present. Abdomen first to fifth segments and single on black with basal segmental white sixth. Comb on eighth segment bands. Wing scales dark with with 25 to 40 scales in irregular scattered pale scales extending from patch. Air tube 3 X 1 ; pectén even, base of costa to humeral cross vein. reaching beyond one-third of tube, Legs black with mixture of pale followed closely by tuft of four to scales; tarsi mostly black. six medium hairs; apical setae 3iate genitalia (fig. 36).—Side- shorter than lateral valve. Anal pieces about three times as long as segment longer than wide, not wide; apical lobe small, elongated, ringed by plate; anal gills pointed and narrowly attached with few and about as long as segment. short spines; basal lobe small, ele- Bionomics.—Craig and Pienkow- vated into transverse ridge at base ski {21) found canadensis near with row of long setae and slender Circle, and also they reported it to spine at margin. Claspette lightly be the dominant pest mosquito in hirsute except at apex ; filament ex- late July of 1955 at a locality near panded in gradual curvee near Eielson Air Force Base. These are middle. the only records for the species from Larva (fig. 37).—Both pairs of Alaska (map 9). They are of head hairs single. Comb on eighth special interest since the area be- segment in two irregular rows. tween Eielson and Fairbanks was Air tube about 3X1; evenly spaced 50 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
FiGUEE 36.—Aedes cataphylla male genitalia.
pectén teeth to hair tuft and three to five widely spaced teeth beyond. Anal segment with plate extending PN-844 well down sides; anal gills as long FIGURE 37.—Aedes cataphylla larva. or longer than segment. Bionomics.—This is a less com- scales and central patch of brown mon species found in central Alaska scales on anterior surface. from Anchorage north to Fair- Male genitalia (fig. 38).—Side- banks and west to Teller (map 7). pieces twice as long as wide, broad, Larvae occur in shallow temporary and sharply tapered to densely or semipermanent pools in Carex or spined apex. Clasper subapically C alœmagrostis marshes. During inserted, with forked arras of 1948 larvae were collected at nine unequal length. Claspette two localities during the last week of May and at one locality near An- chorage on September 15.
Aedes einer eus Meigen
Aedes cinereus Meigen, System. Beschr. Bur. Zweifl. Ins., v. 1, p. 13. 1818. Female.—Mesonotum clothed with reddish-brown scales. Post- coxal scale patch present. Probasi- sternum bare. Lower mesepimeral bristles absent. Abdomen black without white bands or with nar- row partial or complete ones;
lateral spots usually joined to form PN-846 line. Wing scales dark. Legs dark FiGUBE 38.—Aedes cinereus male geni- brown ; coxa of front leg with white talia. THE MOSQUITOES OF ALASKA 51 branched with three spines at apex been collected at. Anchorage and of each branch. Valdez. The species has also been Larva (fig. 39).—Antennae taken in the timdra zone at Nome shorter than head. Upper head and Kotzebue (map 4). Partially hairs tliree to seven, lower two to shaded, shallow, semipennanent five, tufts set close together. pools in Carex and Calamagrostis Lateral abdominal hairs double on marshes are favored liabitats for first and second segment, single and the larvae. At Fairbanks in 1948 long on third to sixth. Comb on fourth-stage larvae were collected eighth segment with 10 to 12 from May 26 througli July 15 and slender pointed scales. Air tube were most numerous about June 3. about 3 X 1 ; pectén extending past No fourth-stage larvae were taken middle of tube, last three or four at Anchorage until June 20, but teeth detached, tuft with two or they persisted until October 8 and three hairs; apical setae very short. were most numerous on September Anal segment longer than wide, 15. The species is easily recog- not ringed by plate ; gills very long nized in the adult stage and has not and lanceolate. been observed to be a serious pest Bionomics.—This species has in Alaska. been taken in largest nmnbers near Fairbanks, but larvae have also Aedes communis (DeGeer) Ctilex communis DeGeer, Mem. Servir Hist. Insectes, v. 6, p. 316, figs. 2 and 5. 1776. Aedes prolixus Dyar, Insecutor Inscitiae Menstruus 10: 2. 1922. Female.—Mesonotum dull yellow or gray scaled with narrow pale median line separating paired dark- brown lines and with posterior brown half lines. Coloration vari- able and may be brown scaled cen-. trally with mixture of pale scales and border of grayish-yellow scales. Postpronotum with setae in single or irregular double row. Postcoxal scale patch absent. Sternopleuron with scales extending to frontal border (fig. 30, 5, p. 44). Probasi- sternum with posterior part bare. Lower mesepimeral bristles two to five. Abdomen dark brown witli basal white bands. Wings dark scaled with patch of two or three to many pale scales at base of costa. Legs dark with femora partially pale. Male genitalia (fig. 40).—bide- pieces about three times as long as wide; apical lobe large, rounded, with many long spinelike setae; basal lobe small, quadrilateral in PN-846 outline, partially detached at base, surface with some small setae. FIGURE 39.—Aedes ciñeren s larva. 52 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE Umiat, Kotzebue, and Teller. Lar- vae have been found in a wide va- riety of pools and appear to be able to live in practically all shallow pools that are temporary but last long enough for adult emergence. Larval population density is often as high as 500 per dip in Sphag- wwrn-heath bog pools. At Anchor- age in 1948 peak adult emergence occurred about May 26 and in re- duced numbers continued until the last of June. Some fourth-stage larvae were found as late as Sep- tember 15. At Fairbanks peak adult emergence was reached about June 6, and no larvae were found after June 15. The frequency of collection and high population density of pools producing communis may exagger- ate the real importance of this spe-
PN-847 FiGUEE 40.—Aedes communis male genitalia. several larger curved ones and stout spine on margin. Claspette lightly hirsute on basal half, apical half more slender; filament angularly expanded to its maximum width near base. Larva (fig. 41).—Both pairs of head hairs single. Lateral abdomi- nal hairs double on first to fifth segment and single on sixth. Comb on eighth segment with 50 to 60 scales in triangular patch. Air tube stout and about 2i/4 X 1 ; pec- ten evenly spaced to near middle of tube, tuft of four to six hairs. Anal segment longer than wide, plate ex- tending only about two-thirds dis- tance down sides, anal gills one to three times length of anal segment. Bionomics.—This species is one of the most common and widely dis- tributed species in Alaska (map 1). Although it is predominantly a PN-848 forest species, it has been taken at FIGURE 41.—Aedes communis larva. THE MOSQUITOES OF ALASKA 53 cies. The high population density tempts the collector to sample such pools and pay relatively less atten- tion to the vastly more numerous pools where larvae are often hard to find and where species other than Gommunis predominate. This fact combined with some evidence that communis may not attack man to any great extent (Hocking 65) raises a serious doubt as to the actual pest importance of the spe- cies in Alaska.
Aedes decticus Howard, Dyar, and Knab Aedes decticus Howard, Dyar, and Knab, Mosquitoes of No. and Cent. Amer., V. 4. p. 737. 1917. Aedes pseudodiantaeus Smith, Brooklyn Ent. See. Bui. 47 :19. 1952. Female.—Torus with integument dark brown or black. Occiput with white and pale-yellow scales, sub- dorsal patches of dark brown, and scattered erect dark scales. Meso- notum with median brown stripes PN-849 separated by line of pale-yellow FIGURE 42.—Aedes decticus male geni- scales; posterior half stripes usu- talia. ally distinct. Postcoxal scale patch absent. Sternopleuron with 5 to 10 Larva (fig. 43).—Antennae al- setae, of which a vertical line of 1 most as long as head with one long to 4 is just anterior to lower edge of and two short setae at apex, anten- mesepimeron. Lower mesepimeral nae tuft just before middle. Up- bristles absent. Abdomen without per and lower head hairs single or basal white bands or occasionally double. Comb on eighth segment of with narrow bands on some seg- five to seven scales, each scale with ments. Wing scales dark. Legs long median spine and fringe of black with femora partially pale basal lateral spinules. Air tube 3 or scaled. 4X1; pectén extending to about Male genitalia (fig. 42).—Side- middle with one to three detached pieces more than twice as long as teeth, hair tuft even with last wide; apical lobe a flattened elon- pectén tooth. Anal segment longer gated oval extending almost to than wide and nearly ringed by basal lobe, ventral side with large plate. dense tuft of fine setae; basal lobe Bionomics.—This is a forest spe- with long spine at its base and two cies recorded from larvae collected curved spines on its apical projec- in black spruce bog pools near Fair- tion. Claspette stout basally and banks and from quaking bog pools narrowed beyond curved shoulder in the Copper Kiver Valley near near apex, shoulder bearing small Chitina (map 9). Larvae taken at setae; filament of claspette slender the latter locality were reported by at base, greatly expanded and end- Frohne and Frohne (4.0) to be asso- ing in two small points. ciated with Culiseta morsitans, 54 AGR. HANDBOOK 182, U.S. DEPT. OP AGRICULTURE anterior to and below lower edge of mesepimeron. Lower mesepimeral bristles absent. Abdomen without basal white bands or occasionally with narrow bands on some of seg- ments. Wing scales dark. Legs black with femora partially pale scaled. Male genitalia (fig. 44).—Side- pieces more than twice as long as wide; apical lobe conical, well de- veloped, projecting mesally, ven- tral side at base with dense group of fine long setae; basal lobe with long stout spine at its base and two broad stout spines on its apical pro- jection. Claspette broad basally and constricted beyond middle to form sharp angular projection bearing several small setae; fila- ment greatly expanded and ending in recurved point. Larva (fig. 45).—Antenna longer than head with three setae of equal length at apex, antennal tuft with few hairs near middle. Upper head hairs two to five; lower two PN-860 to three. Comb on eighth segment FiGUEE 43.—Aedes decticus larva.
Culex territans, and several species of Aedes. At Fairbanks fourth- stage larvae were taken on May 29. Adults believed to be decticus were collected at Fort Yukon on July 5.
Aedes diantaeus Howard, Dyar, and Knab
Aedes diantaeus Howard, Dyar, and Knab, Mosquitoes of No. and Cent. Amer., v. 4, p. 758. 1917. Female.—Torus with integument of outer side yellow to light brown. Occiput with pale-yellow scales. Mesonotum with narrow median brown stripes separated by faint line of yellow scales ; posterior half lines indistinct; sides pale yellow-
ish. Postcoxal scale patch absent. PN-8B1 Stemopleuron with 12 to 20 setae, FiQTTBE 44.—Aedes diantaeus male of which a patch of 7 to 12 is just genitalia. THE MOSQUITOES OF ALASKA 55 June 10 and at Anchorage from May 10 until October 8.
Aedes excrucians (Walker) Culex excrucians Walker, Insecta Saund- ersiana. Díptera, v. I, p. 429. 1856. Aedes alopo-notimi Dyar, Insecutor In- scitiae Menstruus 5: 98. 1917. Female.—Torus with inner sur- face predominantly white scaled. Mesonotum yellowish white with median brown stripe, varied pat- tern of brown and white scales or completely reddish-brown scaled. Mesepimeral bristles absent or rarely there may be one. Abdomen black with basal segmental white bands and frequently with scat- tered white scales. Wings predom- inantly dark scaled with pale scales intermixed. Legs black with tar- sal white bands broad on hind legs and usually absent on last segment of midtarsus and last two segments of fore tarsus; tarsal claw large with tooth long and parallel (fiff. 46,5). Afole genitaJia (fig. 46, A).— Sidepieces about three times as long as wide ; apical lobe prominent with small setae; basal lobe slightly raised, rugose, and extending to base of apical lobe, surface covered FIGURE 45.—Aedes diantaeus larva. with short setae. Claspette hirsute with about 6 to 13 scales, each scale except at apex; filament angularly a long median spine without lateral expanded to sharp point near base. fringe of spinules. Air tube about Larva ( fig. 47).—A n t e n n a e 1 X 3; pectén extending to about shorter than head. Upper head middle with one to three detached hairs triple, lower usually double. teeth followed by tuft of long hairs. Lateral abdominal hairs usually Anal segment longer than wide, double on first and second or third nearly ringed by plate. segment and single on rest. Comb Bionomics.—This is a forest spe- on eighth segment of about 20 to 25 cies, of which small numbers of lar- scales in triangular patch. Air tube vae have been collected near An- slender, about 4X1; pectén not chorage, Big Timber, Chitina, and reaching middle with last two or Fairbanks (map 4). Larvae tend three teeth detached, tuft even with to be associated with Aedes functor in semipermanent pools or along last pectén tooth ; lateral valve with the shallow marshy margins of per- hook-shaped setae at apex. Anal manent pools and ponds. Fourth- segment longer than Avide, plate stage larvae have been taken at extending well down side; anal gills Fairbanks from May 26 until slightly longer than segment. 56 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE merous and troublesome. The habit of biting during warm sunny afternoons when few other mos- quitoes are active increases the pest importance of this species. Popu- lations are more localized than those of the dark-legged species, at least during years when mosquitoes are exceptionally numerous. They are
PN-8B3 riGUKE 46.—Aedes excrucians : A, Male genitalia; B, claw of female. Bionomics.—This species is widely distributed through low for- ested areas from Wrangell north to Fort Yukon and west to Naknek. PN-8B4 In the northwest it has been col- FiGUKE 47.—Aedes excrucians larva. lected at Kotzebue and Noatak most numerous near rivers in areas (map 5). Larvae are prevalent in where there are extensive marsh- semipermanent pools containing an lands. emergent cover of Carex rostrata and Equisetum ßuviatile or in tidal Aedes fitchii (Felt and Young) flats containing Triglochin. A wa- ter depth of 8 to 12 inches is fa- Culex fitchii Felt and Young, Science vored. Peak adult emergence oc- (n.s.) 20 : 312. 1904. curs at Anchorage near the first of Female.—Torus with white scales June and about 2 weeks later at on dorsal half. Mesonotum yellow- Fairbanks. The species is thus near ish white to light brown with broad the end of the Aedes species succes- median brown stripe or variable sion series. Of the five band-legged pattern of brown and light scales. species, it appears to be the most nu- Lower mesepimeral bristles none to THE MOSQUITOES OF ALASKA 57 two, rarely three or four. Abdo- men black with basal white bands, sometimes with apical white scales that may extend into median white line. Wings dark scaled, usually with admixture of white scales along costa. Legs black ; tarsi with basal white bands on all except last two segments of fore tarsus and first segment of midtareus, white bands broader on hind legs; tarsal claw with short tooth not parallel with claw (fig. 48, B). Male genitalia (fig. 48, A).— Sidepieces about three times as long as wide ; apical lobe prominent and slightly elongated, surface clothed with long setae bordered by number of short ones ; basal lobe triangular, densely tubercular with many setae, those at margin of base longer and preceded by spine. Claspette lightly hii-sute except at apex ; fila- ment short and sickle shaped with notch at base. Larva (fig. 49).—Upper head hairs two to four, lower two to three. Lateral abdominal hairs
FIGURE 49.—Aedes fitohii larva. usually double. Comb on eighth segment with many scales in tri- angular patch. Air tube slender and tapering, four or more times longer than wide ; closely set pectén teeth to middle of tube, occasionally with one or more teeth slightly de- tached, tuft of three to five long hairs set close to end of pectén; apical setae as long as lateral valve. Anal segment longer than wide, plate extending well down sides at base; anal gills long and pointed. Bionomics.—This species has been collected at scattered localities from Cook Inlet north to Fort Yukon, west to Naknek, and in the northwest at Kotzebue and Kiva- lina, but it appears to be most FIGURE 48.—Aedes fitchii: A, Male geni- talia ; B, claw of female. numerous south of the Alaska 58 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE Range (map 8). Larvae occur in semipermanent pools overgrown witli Carex rostrata or Equhetum -ßuwiatile and are usually found in association with larvae of Aeden excrucians. Fourth instars have been collected at Fairbanks from May 19 to June 15 and at Anchor- age between May 17 and June 3. N^owhere does the species appear to be as common as exG?mcian-s.
Aedes flavescens (Müller) Cnlex flavescens Müller, Fauna Insect. Fridrichsdalina, p. 87. 1764. Fevuile.—Torus with dark and light scales. Mesonotum with gold- en-brown scales. Lower mesepim- eral bristles usually absent. Ab- domen completely covered with dull-yellow scales or interspersed with irregular areas of dark scales. Wing with mixture of black and pale-yellowish scales, pale scales
PN-858 FIGURE 51.- -Aeáes flavescens larva. predominating from base of costa to humeral cross vein. Legs brown with mixture of yellow scales; tarsi with broad basal white bands ; tarsal claw elongate with short blunt tooth (fig. 50, 5). Male genitalia, (fig. 50, A).— Sidepieces more than two times as long as wide; apical lobe promi- nently rounded with many setae; basal lobe a rugose slightly elevated area with many setae, stout spine, and several long setae near base, lobe extending nearly to base of apical lobe. Claspette' lightly hirsute witli three stout setae on inner mar- gin of base ; filament angularly ex- panded to rounded point near base. Larva (fig. 51).—Upper head hairs usually three to four, lower usually double. Comb on eighth segment with about 20 to 28 scales, FIGURE 50.—Aedes flavescens: A, Male each scale with long central spine genitalia ; B, claw of female. and small basal spinules. Air tube THE MOSQUITOES OF ALASKA 59 tapering, about 3 X1 ; pectén reach- val associated females will be ing nearly to middle with or with- needed to establish the validity of out one or two detached teeth. these two forms. Anal segment slightly longer than In the "timdra" variety taken at wide; anal gills about as long as Umiat the mesonotum is brown and segment. the "darker markings are absent or Bionomics.—In Alaska this spe- poorly demarcated." The wings cies is known only from the Cook usually have a patch of white scales Inlet area, where it may be locally on the costa. Other characters are abundant on or near tidal flats the same as described above. (map 7). Lai'A'ae occur in shallow Male genitalia (fig. 64, p. 67).— pools containing emergent Triglo- Sidepieces three times as long as chin and Scirpus. The pools ori- broad ; apical lobe long and round- ginate from melting snow and ice ed with short, curved setae; basal but may be maintained by seepage lobe flatly conical with numerous and may be covered by the highest setae and long cur^àng spine near summer tides. In 19-Í8 fourth- base. Claspette pilose, slightly stage lar\'ae were most numerous curved, and expanded near middle ; about June 8. Adults were preva- filament shorter than stem, slightly lent from June 14 through July 31 expanded at middle, and terminat- and persisted in reduced numbers ing in curved point. The charac- through August 18. ters of the male genitalia of this species are the same as those of Aedes hexodontus Dyar A. punctor. Larva (fig. 52).—Upper and Aedes hexodontus Dyar, Insecutor Insci- lower head hairs single to triple. tiae Menstruus 4: 83. 1916. Lateral abdominal hairs single to Female.—Mesonotum yellowish triple on first to sixth segment or to light golden brown with paired rarely four to six branched on dark-brown lines and posterior half lines. Postpronotum with setae in single or irregular double row along posterior margin. Postcoxal scales present. Stemopleuron with scales extending to frontal border. Scu- tellum with yellow or bronzy bris- tles. Probasisternum with white scales on posterior part. Lower mesepimeral bristles two or three. Abdomen black with basal seg- mental white bands. Wings dark scaled with patch of two or tliree to many pale scales at base of costa. Legs black with femora partially pale scaled. Aedes hexodontus as described above has not been foimd in Alaska but has been taken as far north as Prince Rupert., British Cohmibia. Knight [80) stated that hexodontus "appears to have at least two gen-
eral varieties that are based on both PN-8B» adult (female) and lançai charac- ters," but concludes that more lar- FiGUEB 52.—Aede» hexodontus larva. 60 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE second segment. Comb on eighth segment with 5 to 9 or rarely 10 scales in row. Air tube 3X1; pect«n not quite reaching middle of tube. Anal segment ringed by plate or very narrowly open ven- trally. Bionomics.—This is typically a tundra species, which is common in northern and northwestern Alas- ka and south along the Bering Sea to Naknek (map 7). It is also pres- ent in the Alaska Range and Chugach Mountains above or at least near the tree line. Larvae prefer semipermanent pools in Carex or Calamagrostis marshes and are often taken in association with larvae of Aedes puUatus, com- munis, and occasionally impiger or punctor. Larvae of hexodontus resemble punctor very closely, but whenever the two were collected together, hexodontus was always more nearly mature. At Umiat, hexodontus larvae were always found in pure culture (Knight 81). FIGURE 53.—Aedes impiger: A, Male The adults are strong fliers and genitalia ; B, claw of female. remain active at wind speeds up to 10 miles an hour. This species from base of costa to humeral is responsible for much of the severe cross vein. Legs black with femora mosquito annoyance prevalent in and tibiae partially pale scaled; the tundra-covered areas of Alaska. tarsal claw sharply bent with slen- der tooth (fig. 53,5). Aedes impiger (Walker) Male genitalia (fig. 53, A).— Gulex impiger Walker, List of Dipter- Sidepieces about 31/2 times as long ous Insects in Brit. Mus., pt. I, p. 6. as wide; apical lobe rounded, sur- 1848. face with few small setae; basal Aedes nearcticus Dyar, Canad. Arctic lobe conically sloped to basal edge Exped. Rpt 3(C), p. 32. 1919. Aedes impiger, Vockeroth, Canad. Ent. with long setae and spine at margin, 86: 109. 1954. rest of surface bare or with few Not impiger of authors. small setae. Claspette hirsute on Female.—Mesonotum black and basal half; filament angularly ex- sparsely covered with bronzy-brown panded to its maximum width near scales with or without mixture of base. yellowish-white scales around sides, Males of impiger and Aedes ni- entire surface with many black g)ipes may be separated by the bristles. Postpronotum with scales shape of the hind tarsal claw, which scattered over posterior half. Post- is the same in the males as in the coxal scale patch present. Lower females. mesepimeral bristles three to eight. Larva (fig. 54).—Both pairs of Abdomen black with basal seg- head hairs single. Lateral abdom- mentai white bands. Wing scales inal hairs multiple on first segment dark with pale scales extending and double on second to fifth. Comb THE MOSQUITOES OF ALASKA 61 Where impiger occurs, it is the first species to emerge. In 1947 emer- gence at Umiat started about June 22 and continued until July 7 (Jachowski and Schultz 75).
Aedes implicatus Vockeroth Aedes implicatus Vockeroth, Canad Ent 86: 110. 1954. Aedes impiger of authors, not Walker. Female.—Mesonotum with me- dian oblong area of brown scales, usually in form of broad stripe or paired stripes; margins grayish white. Postpronotum with setae in single or irregular double row along posterior margin. Postcoxal scales present. Stemopleuron with scales not extending to frontal border (fig. 30, A, p. 44). Proba- sisternum without white scales on posterior part. Lower mesepimeral bristles one to three, or rarely with none. Hypostigial spot with or without white scales. Abdomen with basal white bands. Wing scales dark with patch of two or three to many pale scales at base of costa. Legs black with femora PN-861 pale beneath. FiGUEE 54.—Aedes impiger larva. Male genitalia (fig. 55).—Side- on eighth segment of 8 to 16 scales, pieces about four times as long as each scale with long central spine wide. Filament of claspette angu- and series of smaller basal lateral larly expanded to sharp point at spines. Air tube about 2i/^ X 1; base. Other characters as in Aedes pectén equally spaced on basal third cataphyUa, page 49. and followed by multiple tuft. Larva (fig. 56).—Antennae short Anal segment as long as wide ; anal and spined. Upper and lower head gills stout and several times length hairs single. Lateral abdominal of segment. hairs double on first to fourth seg- Bionomics.—This is typically a ment and single on fifth and sixth. tundra species common in north- Comb on eighth segment with 15 western and northern Alaska (map to 25 scales, each scale with median 8). Larvae have been collected at spine and lateral basal fringe of localities in the Alaska Range and slightly smaller ones. Air tube Chugach Mountains well below the about 21^ X 1 ; closely set pectén tree line, but it is doubtful that the teeth not reaching middle and fol- species is abundant except at higher lowed by tuft. o,f three or four hairs. elevations. At Umiat larvae have Anal segment longer than wide, been taken from pools in Sphag- plat« extending well down sides iiMm-heath bogs. Farther south and covered with minute spines; collections have been made from anal gills one to two times as long temporary pools in Carex marshes. as segment. 62 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE Bionomics.—This species is com- mon in central Alaska (map 3). It has been recorded from as far south as Juneau and from Kotzebue in the northwest. It breeds in a variety of temporary pools, and it appears to be the first species in the succession series. Adult emer- gence reaches a peak at Fairbanks near the end of May and 2 to 3 weeks earlier at Anchorage. Dur- ing 1948 it was thought to be tlie fourth most numerous species at Fairbanks, where it was observed to be active and biting when the sun was bright and the temperature above 80° F. At such times it was frequently the only dark-legged Aedes in flight.
Aedes intrudens Dyar
Aedes intrudens Dyar, Insecutor Insci- tiae Menstruus 7: 23. 1919. Female.—Flagellum without FIGURE .55.- -Aedes implicatus male white scales on ventral side of first genitalia. segment. Mesonotum bronzy brown with gray scales around mar- gins and rarely with indications of median brown stripes. Postcoxal scale patch absent. Stemopleuron with scales not extending to frontal border. Posterior part of probasi- sternum bare. Lower mesepimeral bristles none to four. Hypostigial spot of scales present or absent. Abdomen black with broad basal white bands. Wing scales dark with or without small patch of pale scales at base of costa. Legs with mixture of pale and dark scales; tarsi mostly black. Male genitalia (fig. 57).—Side- pieces about three times as long as wide; apical lobe prominently rounded with numerous rather long setae; basal lobe represented by large spine at base of one side and two spines on raised projection on other. Claspette with basal half hirsute and forming sharp projec- PN-863 tion ending in stout setae at middle, FIGURE 56.—Aeáes implicatus larva. apical half slender; filament angu- THE MOSQUITOES OF ALASKA 63
shortest duration of the pools in which mosquito larvae can be found. At Fairbanks in 1948 peak abundance of fourth-stage larvae was reached about May 26, and the pools were dry in advance of peak emergence for either Aedes com- munis or functor. Larval popula- tion density seldom exceeded two per selected dip, but the vast num- ber of pools in which larva could develop suggested that the adult population ot intrudens might ex- ceed that of communis or punctor., which originated from more con- gested larval populations restricted to the relatively small number of pools that persisted after June 5. Adult collections made in 1948 and subsequent years when the pools FiGUBE 57.—Aedes intrudens male that produce intrudens were dry genitalia. before the end of May confirmed the relatively greater abundance of larly expanded to sharp point at intrudens in 1948. middle. Larva (fig. 58).—Antennae short- er than head. Upper head hairs usually four, lower two or three. Lateral abdominal hairs double on first segment and single on second to sixth. Comb on eighth segment of 10 to 16 scales, each scale with long median spine. Air tube 21/2 XI; pectén reaching middle with two or three detached teeth fol- lowed by tuft of five to seven hairs; apical setae barely discernible. Anal segment longer than wide, plate extending to near ventral line and ventral margin deeply incised ; anal gills short and blimtly pointed. Bionomics.—This is believed to be an important pest species in the Tanana watershed of central Alas- ka (map 5). Only a few larvae have been found near Anchorage. Temporary snowmelt pools in the more open areas of black spnice muskeg are. preferred lart^al habi- tats. Such pools are usually over- grown with C'arex or Calamagrostis PN-866 and are the most shallow and of FiGUBE 58.—Aedes intrudens larva. 551810 0—61 5 64 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
Aedes nigripes (Zetterstedt) Ciilex nigripes Zetterstedt, Insecta Lap- ponica, p. 807. 1838. Aedes nlpinus of authors (not Linnaeus). Female.—Mesonotum black, sparsely covered with bronzy-brown scales or rarely with indications of median dark lines, sides with or without yellowish-white scales, en- tire surface covered witli many black bristles. Postcoxal scale patch present. Lower mesepimeral bristles one to five. Abdomen black with basal segmental white bands. Wing scales dark with pale scales extending from base of costa to humeral cross vein. Legs black with femora and tibia par- tially pale scaled; fore tarsal claw with tooth about one-fourth as long- as claw and not parallel (fig. 59, B).
PN-867 FIGURE 60.—Aedes nigripes larva.
JIale genitalia (fig. 59, A).— Sidepieces over three times as long as wide ; apical lobe small with few short fine setae ; basal lobe conically sloped to basal edge with large spinelike setae on outer margin and smaller ones on inner part. Clas- pette hirsute except on curved apex; filament about same length as stem, roundly expanded and end- ing in curved point. Larva (fig. 60).—upper and lower liead hairs single. Lateral ab- dominal hairs multiple on first and second segments and double on third to seventh. Comb on eighth segment with 15 to 18 scales. Air tube about 21/2 X 1 ; pectén I'eaching beyond middle, last three teeth de- tached, hair tuft basad of last pectén tooth. Anal segment ringed by plate ; anal gills longer than segment. Bionomics.—This is a typical FIGURE 59.—Aedes nigripes : A, Male tundra species, common along the genitalia; B, claw of female. coast from Teller north to Point THE MOSQUITOES OF ALASKA 65 Barrow and on the arctic side of the Brooks Range (map 9). It is the only species so far known from Point Barrow. Larvae liave been collected near Summit Lake in the Alaska Range and at Thompson's Pass in the Chugach Mountains. From these records it appears likely that nigripes occurs rather gener- ally in mountain localities above the tree line. It is one of the three or four species that contribute to the mosquito problem in northern Alaska.
Aedes pionips Dyar Aedes pionips Dyar, Insecutor Inscitiae Menstruus 7 : 19. 1919. Female.—Mesonotum with dull- yellow or white scales, two broad well-defined dark-brown stripes and posterior half lines, median stripes separated by line of pale scales. Postpronotum with setae in single or irregular double row along pos- terior margin. Postcoxal scales present. Scutellmn with both dark PN-Í68 and light-colored bristles. Pro- FIGURE 61.—Aedes pionips larva. basistemum with white scales on posterior part. Lower mesepi- pectén evenly spaced, not reaching meral bristles one to four, or rarely middle and followed by large multi- with none. Abdomen with or with- ple tuft. Anal segment about as out narrow basal white bands. long as wide, with plate reaching Wing scales dark with small patch only about half distance down of pale scales at base of costa. sides and with notched lateral Ijegs black with femora partially edges, spines on apex of anal plate pale scaled. short and slender ; anal gills longer Male genitalia.—The sidepieces than segment. are slightly longer than those of Bionomics.—This species is wide- Aedes communis (fig. 40, p. 52). ly distributed throughout the There are no other taxonomic dif- forested lowlands from Cook Inlet ferences in the genitalia of these north to the Yukon River (map 6). two species. In the northwest it has been col- The presence of the postcoxal lected beyond the tree line at Kiva- scale patch in pionips males may lina. Larvae have been fomid often be used to separate them from tlie in temporary or semipennanent communis males in which the patch pools in Sphagnum-\\QíiÚ\ bogs, is absent. roadside ditches, tractor tracks, and other small shallow bodies of water Larva (fig. 61).—Antennae long in recently disturbed ground. and well spined. Upper head hairs usually five, lower four. Comb on The species is rather common near eighth segment with 60 to 70 scales, Anchorage but rare north of the each scale with even fringe of Alaska Range. Fourth-stage larvae spinules. Air tube about 2^4X1; have been collected at Fairbanks be- 66 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
tween May 28 and June 13 and at Anchorage from May 15 to July 27. Peak adult emergence occurs from 8 to 10 days lat«r than that of communis. Aedes pullatus (Coquillett) Gulex pullatus Coquillett, Wash. Ent Soc. Proc. 6: 1Ö8. 1904. Female.—Mesonotmn with pale- yellowish to yellowish-brown scales, two median stripes being sometimes indistinct or absent. Postprono- tum with setae in single or irregular double row. Postcoxal scale patch absent. Stemopleuron wàth scales not extending to frontal border. Probasistemum bare. Lower mes- epimeral bristles one to five. Hy- postigial spot of many white scales. Abdomen black with basal white bands. Wings dark scaled with line of pale scales extending from base of costa to humeral cross vein. Legs black with femora and tibiae partially pale scaled. Male genitalia ^fig. 62).—Side- pieces about 31/^ times as long as wide; apical lobe prominent and
PN-870 FiGXJEE 63.—Aedes pullatus lar-va.
somewhat elongated, ventral sur- face covered with numerous setae; basal lobe represented by large spine at margin and two adjacent smaller spines. Claspette with bas- al half large, hirsute, and form- ing rounded projection at middle, apical half slender; filament angu- larly expanded to rounded point near middle. Larva, (fig. 63).—Upper head hairs three to six, lower two to four, hairs short and tufts set close to- gether. Lateral abdominal hairs long and double or triple on first to fifth segment and shigle on sixth. Comb on eighth segment with many PN-869 scales in triangular patch. Air FIGURE 62.—Aedes pullatus male tube 3 X 1 ; pectén teeth closely set, genitalia. not reaching middle, closely fol- THE MOSQUITOES OF ALASKA. 67 owed by large 6- to 7-haired tuft; The taxonomic status of punctor apical setae shorter than lateral is confused by the existence of a valve. Anal segment longer than remarkable variation of stiiicture wide, not ringed by plate, spines on in the lai-vae and of color and scale apex of anal plate long and slender ; pattern in the adults. Larvae of anal gills usually two or three times the foim prevalent along tlie south- longer than anal segment. ern coast are smaller, the aiial plate Bionomics.—This species is does not form a complete ring, and found throughout Alaska in areas the anal gills are short. This form near the tree line; however, larvae has been treated by Knight {81) have been collected at Wrangell and and Frohne {31) as a distinct Valdez at near sea level (map 4). species, punctodes Dyar. How- Small clear snowmelt pools in ever, there is so much intergrada- Carex meadows produce larvae in tion of the distinguishing charac- greatest numbers. The degree of ters that we have chosen to treat development shown by associated punctodes as a synonym of punctor. lan^ae, and Frohne's obsei-vation Among the adults there is also an (38) that larvae were abundant in apparent difference, which distin- pools in McKinley Park when guishes the tundra populations swarms of naale Aedes commimis from those of the forested areas. and impiger were already present, The "tundra" variety has the torus indicate that jyidJatus emerges all dark and the mesonotum brown somewhat later than hexodontus., scaled, with darker markings absent punctor\ ivifiger^ and comviunis. or nearly so. The form from the Records suggest that pullatus is forested area as described above has one of the most important pest spe- the torus paler laterally and the cies in the Chiigach Mountains and yellowish mesonotum marked with Alaska Range at elevations above paired brown stripes. 2,000 feet. Male genitalia (fig. 64).—The Aedes punctor (Kirby) characters of the male genitalia of Culex punctor Kirby, Fauna Boreali- Amer., pt. 4, p. 309. 1837. Aedes cycloceroulus Dyar, Insecutor Inscitiae Menstruos 8: 23. 1920. Aedes leuconotips Dyar, ibid 8: 24. 1920. Aedes punctodes Dyar, ibid 10: 2. 1922. Female.—Toms light brown to black. Mesonotum pale yellow to yellowish brown with paired dark- brown stripes and posterior subme- dian half stripes present or absent. Postpronotum with setae in single or irregular double row along pos- terior margin. Postcoxal scales present. Stemopleuron with scales extending to frontal border. Pro- basisternum with few or no scales. Abdomen black with basal seg- mentai white bands. Wings com- pletely dark scaled or with few pale scales at base of costa. Legs PN-sn black, femora and tibia with or FIGURE 64.- -Aedes punctor male geni- without scattered pale scales. talia. 68 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE this species are the same as those of central Alaska punctor is one of of Aedes hexodontu.s, pfig^ 59. the species most frequently encoun- Larva (fig. 6.5).—Antennae short tered in larval collections. Shal- and spined. Upper and lower head low semipermanent pools in Sphag- hairs single or double. Lateral ab- nwm-heath bogs and Carex or dominal hairs usually single or Calamagrostis marshes are favored double on first to sixtli segments. larval habitats. Population den- Comb on eighth segment with 10 sities are often as high as 300 per to 19 stout scales in irregular row. dip. In southern and central Alas- Air tube 2i/^ X 1; pectén fine and ka larvae were usually found not reaching middle of tube, tuft associated with those of Aedes centrally placed. Anal segment communis and pionips. At Umiat, ringed by plat© or narrowly open Knight {81) found larvae of the ventrally; anal gills II/2 to 3 times "tundra" variety in Sphagnum- as long as anal plate. heath pools, which otherwise con- Bionomics.—The typical variety tained only Aedes nearcticus. of functor is common throughout Frohne [36) reported that larvae the forested areas of central Alaska, of the "tundra" variety of punctor and the "tundra" variety has been were more numerous than those of taken at Umiat, Kotzebue, and any of the other species found at Naknek (map 2). The pwictodes Naknek during May and June of form is abundant in the coastal area 1954 and that hatching started on from Cook Inlet southeastward at April 23. In 1948 fourth-stage least as far as Juneau. Over most larvae of the typical variety were collected from May 10 through September 15, with peak abundance during the first half of June. At Fairbanks fourth-stage larvae were found from May 24 through July 19, with peak abundance about June 5. At Umiat, Knight {81) observed peak abundance near the end of June.
Aedes riparias Dyar and Knab Aedes riparius Dyar and Knab, N.Y. Bnt. Soc. Jour. 15 : 213. 1907. Female.—Torus with inner sur- face predominantly dark scaled. Mesonotum with golden-brown scales and few yellowish-white scales around margins. Mesepi- meral bristles absent. Abdomen usually with evenly intermingled dark and white scales with or with- out partial basal white bands; venter white scaled or with irregu- lar dark-scaled medium areas. Wings predominantly dark scaled wáth pale scales intermixed. Femo- ra, tibiae, and first tarsal segments largely pale scaled, tarsi with basal FIGURE 65.—Aedes punctor larva. white bands, which are broader on THE MOSQUITOES OF ALASKA 69 hind legs; tarsal claw with short tooth not parallel with claw (fig. 66, B ). Male genitalia (fig. 66, A).— Sidepieces about three times as long as wide ; apical lobe prominent and rounded with many curved setae; basal lobe projected in long cone shape at right angles to sidepiece, surface with many setae apically and stout spine at margin with long setae adjacent to it. Claspette lightly hirsute; filament angularly expanded to its maximum width near base. Larva (fig. 67).—Antennae short- er than head. Both pairs of head hairs usually double. Comb on eighth segment with seven or eight thomlike scales in irregular row. Air tube about 3 X1 ; pectén reach- ing nearly to middle with last two teeth detached and followed by three-haired tuft; apical setae barely discernible. Anal segment with plate nearly reaching ventral line near base ; anal gills short and pointed. PN-8T4 FiQUKE 67.—Aedes riparius larva. Bionomics.—Records for this species are based on adults collected at several localities in the Yukon basin of central Alaska (map 7). It appears to be a rare species found in the vicinity of black spruce muskeg. Its large size and golden color make it conspicuous among the innumerable smaller dark Aedes. Aedes Stimulans (Walker) Culex Stimulans Walker, List of Dip- terous Insects in Brit. Mus., pt. I, p. 4. 1848. Female.—Torus with or without white scales on dorsal half. Mes- onotum yellowish wliite to light brown with broad median brown
PN-873 stripe of variable pattern of brown FioxTBE 66.—Aedes riparius: A, Male and light scales. Lower mes- genitalia ; B, female claw. epimeral bristles three or four, 70 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE tube about 3 X 1 ; pectén teeth ex- tending nearly to middle; apical setae shorter than lateral valve. Anal segment longer than wide with plate extending well down sides; anal gills about as long as segment. Aedes Stimulans larvae taken in Alaska have three or four upper and two lower head hairs instead of two upper and one lower as in Stim- ulans larvae taken farther south. Dyar described larvae having the larger number of head hairs as Aedes Tnercurator^ but this species has since been considered a synonym of stinmlans by Dyar and other authors. Bionomics.—This species is rath- er common near Fairbanks and has been taken at several localities be- tween the Chugach Mountains and Alaska Range (map 6). Larvae are PN-876 found in semipermanent pools over- FIGURE 68.- -Aedes Stimulans male grown with Equisetum fluviatile or genitalia. Potentilla palustHs. Fourth-stage rarely one or two. Abdomen black larvae have been collected at Fair- with basal segmental white bands. Wings completely dark scaled or with admixture of white ones along costa. Legs black, tarsi with basal white bands on all except last two segments of fore tarsus and first segment of midtarsus, white bands broader on hind legs; tarsal claw with short tooth not parallel to claw. Male genitalia (fig. 68).—Side- pieces about three times as long as wide; apical lobe with rather long setae; basal lobe low rounded with many short, setae and stout mar- ginal spine. Claspett« hirsute ex- cept at apex ; filament thin and an- gularly expanded to sharp point at middle. Larva (fig. 69).—Upper head hairs three or four, lower two or three. Mesothoracic hair No. 1 double or triple. Comb on eighth segment with about 22 to 35 scales, each scale with median spine and PII-«7« series of smaller lateral ones. Air FiGUEE 69.—Aedes atvmulanê larva. THE MOSQUITOES OF ALASKA 71 banks between June 3 and 12. The emergence is virtually complete be- development period coincides with fore the two other band-legged that of Aedes punctor, and data ob- species, Aedes excrucians and fitchii^ tained in 1948 indicate that adult reach peak emergence.
GENUS CULISETA FELT
KEYS TO SPECIES
Adults
1. Femora with distinct subapical white rings particeps, p. 75 Femora without subapical white rings 2 2. Sternopleuron with scales extending to frontal border; torus with white scales 3 Sternopleuron with white scales not extending to frontal border; torus without white scales 4 3. Tarsi with narrow white rings on some segments; cross veins without scales incidens, p. 74 Tarsi with broad white rings; cross veins with scales alaskaensis, p. 72 4. Tarsi with pale-white rings at both ends of tarsal joints; wings without spots morsitans, p. 76 Tarsi without white rings; wings with faint spots impatiens, p. 73
Larvae
1. Air tube with normal pectén teeth on basal fourth not followed by long hairs morsilans, p. 76 Air tube with normal pectén teeth near base followed by series of long hairs extending beyond middle 2 2. Upper and lower head hairs multiple and about equal in number and length impatiens, p. 73 Upper head hairs short and multiple, lower longer and less numerous. _ 3 3. Postclypeal hairs four to five branched and about as large as head hairs; posterior margin of anal plate with short spines at apex near dorsal brush particeps, p. 75 Postclypeal hairs smaller and more delicate than head hairs; anal plate without spines 4 4. Antennae pigmented and prominently spined; anal plate pierced by two or three tufts__ alaskaensis, p. 72 Antennae not pigmented and not prominently spined; anal plate either without or pierced by one or two tufts incidens, p. 74
Male Genitalia
1. Apical lobe absent morsilans, p. 76 Apical lobe present .-- 2 2. Eighth segment with row of 20 to 40 short spines on basal margin; basal lobe large with single spinelike setae impahens, p. 73 Eighth segment with less than 12 spines on basal margin; basal lobe with 2 or 3 spines . _^ 3. Apical lobe with many setae and one spine mcidens, p. li Apical lobe with setae only 4. Eighth segment without spines or with single short spine at center of basal margin particeps, p. U Eighth segment with about eight stout spines alaskaensis, p. 7^ 72 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
Culiseta alaskaensis (Ludlow) Theohaldia alaskaensis Ludlow, Ganad. Ent. 38: 326. 1906. Female ( frontispiece).—Torus white scaled. Flagellum with first segment white scaled ventrally. Mesonotum with even mixture of brown and white scales, sometimes marked with pair of median white spots. Sternopleuron with scales extending to frontal border. Ab- domen black with basal segmental white bands. Wing scales dark, scales forming spots at base and fork of second vein, along cross veins, at base and fork of fourth, upper fork of fifth, and middle of sixth veins. Legs black with wide basal white bands that are broadest on hind legs. Male genitalia (fig. 70).—Side- pieces more than twice as long as wide; apical lobe a low rounded area densely covered with small setae ; basal lobe large, conical, cov- ered with small setae, apex with two
PN-878 FiGTJKE 71.—Culiseta alaskaensis larva.
stout spines. Lobes of ninth tergite broad, rounded, and bearing 7 to 10. slender setae. Eighth segment with about eight stout spines. Larva (fig. 71).—Antennae pig- mented, distinctly spined, and equal to or slightly shorter than distance between two antennae. Upper head hairs five or six, lower three or four. Postclypeal hairs smaller and more delicate than head hairs. Air tube 2 X1 ; 8 to 12 pectén teeth on basal fourth followed by long hairs that extend nearly to apex, paired tufts arising close to base between pectén rows. Anal seg- ment about as long as wide, ringed by plate with two or three tufts piercing plate. Bionomics.—This species is com- PN-e77 mon in forested lowland areas from FIGURE 70.- -Culiseta alaskaensis male Haines north to the Yukon Eiver genitalia. and west to Naknek (map 12). THE MOSQUITOES OF ALASKA 73 Larvae develop in shallow semi- Male genitalia (fig. 72).—Side- permanent or permanent pools that pieces stout conical, about twice as are clogged with debris and vegeta- long as wide; apical lobe a small tion, often in association with slightly elevated chitinized area Anopheles earlei, Culex terntans, with long setae; basal lobe large and in the more southern part of and conical in outline, apex round- its range with Culiseta iynpatiens. ed with one large spinelike seta Overwintering adults appear dur- and several smaller ones. Lobes of ing early April near Anchorage ninth tergite only slightly sepa- and in early May at Fairbanks. rated and each bearing about 10 Activity is greatest during May and long setae. Eighth sèment with the first half of June. During 1948 row of 20 to 40 short stout spines on fourth-stage larvae were found at basal margin. both Fairbanks and Anchorage Larva (fig. 73).—Antennae slight- from the middle of June until mid- ly longer than distance between September. Peak abundance at two antennae. Both pairs of head both localities occurred about the hail's multiple and long. Lateral second week in July. Adults abdominal hairs multiple on first emerge from late June until fall, to fifth segment and double on and studies by Frohne {33) have sixth. Air tube stout, 2 X 1 ; shown that the females do not take pectén of 10 to 15 teeth on basal blood meals until the following fourth followed by long hairs that spring. nearly reach apex of tube, paired In some localities alashaensis is tufts large and arising close to base sufficiently numerous to cause seri- between rows of pectén. Anal seg- ous annoyance for a full month or ment wider than long, ringed by even 6 weeks in advance of Aeden plate with two to three anterior emergence. Its habit of emerging from hibernation while much of the winter snow still covers the ground has caused it, together with impatient, to be known locally as "the snow mosquito."
Culiseta impatiens (Walker)
Culex impatiens Walker, List of Dipter- ous Insects in Brit. Mus., pt. I, p. 5. 1848. Female.—Torus and first seg- ment of flagellum without white scales. Mesonotum with brown and yellowish scales, two fine pale lines extending posteriorly from median pale patches and variable pattern of other pale scales. Stemopleuron with scales not ex- tending to frontal border. Abdo- men black with basal segmentai white bands. Wing scales brown and aggregated to form faint spots at forks of second and fourth veins PN-879 and bases of second and third veins. FIGURE 72.—Culiseta impatiens male Legs black, femora white tipped. genitalia. 74 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE or permanent pools of the same kind as those described for alaskaensis. In fact, larvae of the two species are usually taken from the same pools, at least in the Cook Inlet area. During 1948 the peak abundance was not reached until the second week in August or al- most a montli later than that of alaskaensw. Also during 1948 no impatiens adults were seen prior to May 1, but they were more numer- ous than nlaskaensis after May 19. Few adults were seen after the middle of June. Culiseta incidens (Thomson) Culex incidens Thomson, Kongl. Sven. Freg. Resa, Dipt., v. 6, p. 443. 1868. Female.—Torus white scaled. Flagellum with first segment white scaled ventraUy. Mesonotum with dark-brown scales and mixture of yellowish scales, some of which form partial longitudinal lines or spots. Stemopleuron with scales extending to frontal border. Ab- domen black with basal segmental white bands. Wing scales dark, aggregated into patches on fork and base of second vein, fork of second and fourth veins, upper fork of fifth and middle of sixth veins.
PN-880 Legs dark brown with narrow faint-white rings on bases of some FIGURE 73.—CuUseta impatiens larva. of tarsal joints, femora and tibia tufts of ventral brush punctur- with narrow white rings at their ing plate and with tuft of small apices. hairs near posterior margin; anal Male genitalia (fig. 74).—Side- gills longer than segment. pieces more than twice as long as Bionomics.—This species occurs wide; apical lobe a small elevated in the Panhandle northward to the area with a number of small setae Cook Inlet area, where it seems to and long spine; basal lobe small be more nmnerous than Culiseta and conical with small setae, apex aldskaen.ús. In the west it has been with two stout spines. Lobes of reported from Naknek {36) and ninth tergite slightly separated, Unalakleet, and one adult has been each bearmg five to eight rather taken at Nome (map 11). Al- long setae. Eighth segment with though it occurs at Fairbanks, the five to eight spines on basal margin. species appears to be quite uncom- Larva (fig. 75).—Antennae not mon north of the Coast Ranges. pigmented and not prominently Larvae are found in semipermanent spined. Both pairs of head hairs THE MOSQUITOES OF ALASKA 75 multiple, lower tufts longer and fewer in number than uj^per. Postclypeal hairs smaller and more delicate than head liairs. I^ateral abdominal hairs miütiple on fii-st and second segments and double on third to sixth. Air tube stout, about 2X1; pectén witli few basal teeth that have one or two minute denticles, teeth followed by long hairs to apical third of tube, mul- tiple tuft near base between rows of pectén. Anal segment ringed by plate; tufts of ventral brash absent or with one to two puncturing plate and a small one- to three-haired tuft on lateral posterior margin; anal gills slightly longer than segment. Bionomics.—Lan^ae of tliis spe- cies and one adult liave been col- lected at Jun eau (FrohneJÖ) (map 12). Records if rom Matanuska (Stage and Chamberlin 99) are be- lieved to have been in error and probably refer to OuUseta alaskaerisis.
PN-882 FIGURE 75.—Culiseta incidenn larva.
Culiseta particeps (Adams) Culex particeps Adams, Kans. Univ. S'i. Bui. 2, p. 26. 190.3. Culiseta maccraekcnae Dyar and Knab, Wash. Biol. Soc. Pro-- 19: 13.3. 1906. Female.—M e s o n o t u m dark brown with light-brown median stripe and narrow white posterior half lines; sides, anterior margin, and margins of antescutellar space with mixture of white scales. Ab- domen black with basal segmental white bands and few scattered wliite scales. Wing scales black with few pale scales on costal veins, dark scales forming spots at base of second vein, forks of second and PN-88I fourth veins, upper fork of fifth vein, and on cross veins. Legs FiGtniE 74.—Culiseta incidens male genitalia. black with part of inner side wliite 76 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE scaled, femora with subapical white white half lines. Stemopleuron ring followed by black ring, apical with scales not extending to frontal segments of tarsi without rings and border. Abdomen brown scaled succeeding tarsi with gradually with scattered yellowish-white broadening white rings. scales, mostly heavily concentrated Male genitalia.—Sidepieces about along apices and bases of segments, three times as long as wide; apical or these may occasionally form lobe a small elevated area with basal pale bands only. Wing scales number of long setae; basal lobe dark with pale scales at base of small and conical with many small costa. Legs dark with faint-white setae, apex with two or three stout rings at both ends of tarsal joints. spines. Lobes of ninth tergite not Male genitalia (fig. 76).—Side- separated but indicated by two pieces conical, more than twice as large groups of small spines. long as wide; apical lobe absent; Eighth segment without spines or basal lobe prominent and conical with one spine at center of basal with three to five spines on apex margin. and small setae on sides. Lobes of Larva.—Both pairs of head hairs ninth tergite with broad projec- multiple, lower with about three tions, each with 6 to 12 slender setae. long hairs, upper more numerous Eighth segment with group of small and shorter. Postclypeal hairs four to five branched and about as spines centrally on basal margin. long as head hairs. Mesothoracic Larva (fig. 77).—Upper head hair No. 3 less than six times pro- hairs multiple, lower double. Lat- thoracic hair No. 0. Air tube stout, about 2 X 1 ; pectén with few basal teeth followed by long hairs that extend nearly to apex of tube, paired tuft near base of tube be- tween rows of pectén. Anal seg- ment ringed by plate with two anterior tufts of ventral brush aris- ing from cleft in plate and small patch of short bristles near apex of plate ; anal gills slightly longer than segment. Bionomics.—Larvae believed to belong to this species were collected from a roadside ditch at Wrangell (Frohne and Sleeper 1^2) (map 12). If they are correctly identified, this is the only record for the species north of southwestern Oregon.
Culiseta morsitans (Theobald) Culex morsitans Theobald, Monog. of Culicidae of World, v. II, p. 8. 1901. Female.—Torus and first segment of flagellum not white scaled. Mesonotum brown with mixture of yellowish scales around margins, PIÍ-883 pair of faint nearly bare median FIGURE 76.—Culiseta morsitans male stripes, and posterior yellowish- genitalia. (Courtesy A. R. Barr.) THE MOSQUITOES OF ALASKA 77
GENUS ANOPHELES MEIGEN Anopheles earlei Vargas Anopheles earlei Vargas, Pan Amer. Union Bol. de la Ofic. Sanit. 22:8. 1943. Female.—Palpi as long as pro- boscis, dark brown. Mesonotum with pruinose gray stripe bordered by dark bands, median stripe with hairlike yellowish scales. Wing scales dark brown and aggregated into spots at base of second vein, at forks of second and fourth veins, and at cross veins, second vein be- tween cross veins and fork with niunerous dark scales, spot of pale scales at apex of wing. Legs black, apices of femora and tibiae with PN-884 pale-yellowish scales. Male genitalia (fig. 78).—Clasp- FiGUBE 77.—Culiseta morsitans larva. ettes bilobed, with two (sometimes eral abdominal hairs multiple on three) spines on ventral lobe and first and second segments, single usually with two spines on dorsal and long on third to sixth. Air lobe. Claspers with bases covered tube about 6X1; pectén with six with dense patch of nonpapillated to nine teeth on basal fourth, paired hairs. Mesosome with four pairs of tuft at base between rows of pectén. nonserrated leaflets. Ninth tergite Anal segment longer than wide and ringed by plate; anal gills slender and longer.than segment. Bionomics.—This infrequently collected species has been recorded from scattered localities within the forest zone from Anchorage noirth to Fairbanks and in the southwest at Naknek (map 10). Larvae are often found associated with Aedes excrv/dans in semipermanent and permanent pools that are over- grown with Carex rostrata. In the Anchorage area Frohne {32) found larvae associated with Culiseta alas- kaensis and impatiens in Myrica- Sphagnum bogs. In 1948 fourth instars were found at Fairbanks from June 15 to July 19 and at Anchorage from May 31 to Au- gust 16. Little is known concern- ing the biology of this species. It FIGURE 78.—Anopheles earlei male geni- is not known to bite man. talia. AGR. HANDBOOK 182, U.S. DEPT. OF AGRICtJLTURE
PN-886 FIGURE 79.—Anopheles carlei larva. THE MOSQUITOES OF ALASKA 79 with lobes usually short and with GENUS CULEX LINNAEUS apex broadened or obliquely trmi- cate. Culex territans Walker Larva (fig. 79).—Head longer Culcx tcrritnns-Wa.\kev, Insecta Saunder- than wide. Postclypeal hairs two to siana, Diptera, v. I, p. 428. 1856. Ciih'x apicaliis Adams (of Dyar and other five branched, brandling usually authors, not Adams). short distance from base. Inner clypeal hairs bifurcate near middle Female.—M e s o n o t u m brown or with few additional fine branches scaled witli median indistinct and set close together. Frontocly- nearly bare lines and usually with peal sclerite pale banded. Abdomen two median spots of yellowish with palmate tufts on third to scales. Abdomen black scaled with seventh segments, antepalmate haii-s apical segmental white bands. on fourth and fifth segments with Wing scales all black. Legs black, two to four branches. Anal seg- undersurface partially white scaled. ment longer than wide, dorsal plate J/ale genitalia (fig. 80).—Side- with long single latei-al hair; anal pieces more than twice as long as gills as long as segment and bluntly wide; subapical lobe with two pointed. large rods, spine, and five hooked Bionomics.—This rather uncom- mon species is widely distributed throughout the forested lowlands from Cook Inlet north to the Yukon River (map 10). Larvae live in pools and ponds or along lake shores that are permanent or dry for only a short time during the late sum- mer. These habitats usually sup- port an emergent cover of Equise- turn, Typha^ or Carex rostrata, and larvae are always associated with floating or partly submerged plants such as Lemna, RanvMctdus, and Utricidana. Overwintering adults appear in early May and disappear during early June. In 1948 fourth instars were most numerous about July 1 at Fairbanks and July 7 at Anchorage. Few larvae were col- lected after July 10. Although the adult females bite readily, they have not been observed in numbere suffi- cient to cause serious annoyance. Alaskan records for Anoph-ehs mamdipennis and occidentalis refer to earlei Frohne {37) has reported that although Alaskan earlei ap- pears structurally similar to earlei of Montana, there are pronounced physiological and behavioral differ- FIGURE 80.—Culex territans male geni- ences between the two populations. talia. 80 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE filaments, fii-st three partially ser- August 20 and were most numerous rated. Tenth steniite prominent, about July 27. At Fairbanks they apex broad, extending beyond meso- were taken from June 9 through some and terminating in row of September 7, with a peak abundance short setae. Mesosome halves with about July 3. Larvae are able to relatively even oblong outlines ter- survive in pools containing such minating apically in rounded ser- high populations of insect preda- rated margin, halves joined by tors that all Aedes and Gvliseta sclerotized band near apex. larvae are eliminated. Adults are Larva (fig. 81).—Antennae large, seldom seen. They are known to cylindrical, and spined. Head hairs feed on frogs. single or double. Lateral abdomi- nal hairs multiple on first and sec- ond segments and double on third to sixth, secondary haii-s numerous and well developed. Comb on eighth segment with numerous scales in triangular patch. Air tube long and tapering, about 7X1; pectén of 12 to 14 teeth on basal third of tube with four pairs of prominent tufts beyond pectén and also sometimes small fifth pair near apex. Anal segment ringed by plate, longer than wide. Bionomics.—This species is dis- tributed throughout the forested lowlands from Valdez and the Cook Inlet area north to the Yukon River (map 9). Larvae live in pennanent or almost permanent pools and ponds as well as along lake shores. Favored habitats support an emer- gent cover of Eqimetum., Carex rostrata., or Scirpus validm, contain Ranimculus, and often have a float- ing cover of Lemna. In 1948
fourth-stage larvae were found at PN-8g8 Anchorage from June 16 through FIGURE 81.—Gulex territans larva. THE MOSQUITOES OF ALASKA 81 Literature Cited
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(44) GAHAN, J. B., LABBECQXJE, G. C, and BOWEN, C. V. 1955. AN APPLICATOR FOR ADDING CHEMICALS TO FLOWING WATER AT UNIFORM RATES. Mosquito News 15 : 143-147, illus. (45) and MULHERN, T. D. 1955. FIELD STUDIES WITH WATER-SOLUBLE INSECTICIDES FOR THE CONTROL OF MOSQUITO LARVAE IN CALIFORNIA PASTURES. MOSquitO NeWS 15: 139- 143, ¡llus. (46) and XOE, J. R. 1955. CONTROL OF MOSQUITO LARVAE IN RICE FIELDS WITH WATER-SOLTTRLE PHOSPHORUS INSECTICIDES. JOUF. ECOH. Ent. 4S : 665-667. (47) GILBERT, I. H., GOUCK, H. K., and SMITH, C. N. 1955. NEW MOSQUITO REPELLENTS. .Tour. Econ. Eut. 48 : 741-743. (48) GINSBURG, .J. M. 1930. STUDIES OF PYRETHRUM AS A MOSQUITO LARVICIDE. N.J. Mosquito Extermin. Assoc. Proc. 17 : 57-72, illus. (49) GJULLIN, C. M. 1938. A MACHINE FOR SEPARATING MOSQUITO EGGS FROM SOIL. U.S. Bur. Ent. and Plant Quar. ET-135, 4 pp.. illus. (.50) and CROSS, H. F. 1950. THE EFFECTIVENES,S OF SEVEN INSECTICIDES AGAINST ALASKAN MOSQUITO LARVAE IN DIFFERENT TYPES OF BREEDING AREAS. Amcr. MoSquitO Control Assoc. and Va. Mosquito Control Assoc. Proc and Papers 1950, pp. 75-77. (51) HEGARTT, C. P., and BOLLEN, W. B. 1941. THE NECESSITY OF A LOW OXYGEN CONCENTRATION FOR THE HATCHING OF AEDES MOSQUITO EGGS. .Tour. Cell, and Comi)ar. Physiol. 17: 193-202. (.52) and ISAAK, L. W. 1957. PRESENT STATtrS OF MOSQUITO RESISTANCE TO INSECTICIDES IN THE SAN JOAQUÍN VALLEY IN CALIFORNIA. Mosqulto News 17 : 67-70. (.53) IsAAK, L. W., and SMITH, G. F. 19.53. THE EFFECTIVENESS OF EFN AND SOME OTHER ORGANIC PHOSPHORUS INSECTICIDES AGAINST RESISTANT MOSQUITOES. MoSqultO NcWS 13 : 4-7. (54) and PETERS, R. F. 1952. RECENT STUDIES OF MOSQUITO RESISTANCE TO INSECTICIDES IN CALI- FORNIA. Mosquito News 12 : 1-7. (55) and PETERS, R. F. 19.56. TESTS WITH AERIAL SPRAYS OF MALATHION FOB THE CONTROL OF MOSQUITOES. Mosquito News 16 : 84^86. (.56) WILSON, C. S., TRAVIS, B. V., and HUTTON, G. L. 1949. THE RELATIVE EFFECTIVENESS OF SEVERAL INSECTICIDES AGAINST MOSQUITO LARVAE IN ALASKA. MosQuito Ncws 9: 142-145. (57) and YATES, W. W. 1946. THE SURVIVAL OF AEDES VEXANS AND AEDES LATERALIS EGGS IN NATURE. Calif. Mosquito Control Assoc. Ann. Conf. Proc. and Papers 14: 89-92, illus. (58) YATES, W. W., and STAGE, H. H. 19.50. STUDIES ON AEDES VEXANS IMEIG. I AND AEUJES STICTICUS (MEIG.), FLOOD- WATER MOSQUITOES, IN THE LOWER COLUMBIA îtivER VALLEY'. Amer. Ent. Soc. Ann. 43: 262-275, illus. (59) GOLDSMITH, J. B., HUSMAN, C. N., BROWN, A. W. A., and others. 1949. EXPLORATORY STUDIES ON THE CONTROL OF ADULT MOSQUITOES AND BLACKFLIES WITH DDT UNDER ARCTIC CONDITIONS. Mosquito News 9 : 93-96. (60) GRAHAM, .7. E., REES, D. M., and EDMUNDS, G. F., .JR. 1953. A SEASON OF MOSQUITO CONTROL WITH HEPTACHLOR. Calif. MosquitO Control As.soc. Ann. Conf. Proc. and Papers 22: 21-22. (61) HA UFE, W. O. 1954. THE EFFECTS or ATMOSPHERIC PRESSURE ON THE FLIGHT RESPONSES OF AEDES AEGYPTI (L.). Bui. Ent. Res. 45 : .507-.526, illus. (62) HEDEEN, R. A., and KEEGAN. H. L. 19.52. THE USE OF LINDANE AND DIELDRIN AS MOSQUITO ADULTICIDES IN ALASKA. Mosquito News 12 : 242-243. (63) HERMS, W. B., and GRAY, H. P. 1944. MOSQUITO CONTROL. PRACTICAL METHODS FOR ABATEMENT OF DISEASE VECTORS AND PESTS. 419 pp., illuS. N.Y. (64) HiNMAN, E. H. . T 1930 A STUDY OF THE FOOD OF MOSQUITO LARVAE (CULICIDAE). Amer. JOUr. Hyg. 12: 238-270. 84 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
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1953. A LIGHT, PNEUMATIC SPEAYEE FOB INSTALLATION ON VEHICLES. MOS- quito News 13 :134-138, illus. JACHOWSKI, L. A., JR., and SCHULTZ, C. 1948. NOTES ON THE BIOLOGY AND CONTROL OF MOSQUITOES AT UMIAT, ALASKA. Mosquito News 8 : 155-165, illus. JENKINS, D. W. 1948. ECOLOGICAL OBSERVATIONS ON THE MOSQUITOES OF CENTRAL ALASKA. Mosquito News 8 : 140-147, illus. and HASSETT, C. C. 1951. DISPERSAL AND FLIGHT RANGE OF 8UBABCTIC MOSQUITOES MAEKED WITH RADIOPHOSPHORUS. Canad. Jour. Zool. 29 : 178-187, illus. JONES, R. W., Ill, and HOLTEN, J. R. 1949. JEEP EXHAUST VENTURI AEROSOL. Mosquito News 9: 161-165, illus. KELLER, J. C, and CHAPMAN, H. C. 1953. TESTS OF SELECTED INSECTICIDES AGAINST RESISTANT SALT-MARSH MOS- QUITO LARVAE. Jour. Econ. Ent. 46: 1004-1006. KNIGHT, K. L. 1948. A TAXONOMIC TREATMENT OF THE MOSQUITOES OF UMIAT, ALASKA. U.S. Nav. Med. Res. Inst. Rpt. No. 2,12 pp., illus.
1951. THE AEDES (OCHLEROTATUS) PUNCTOB SUBGROUP IN NORTH AMERICA. Amer. Ann. Ent. Sec. 44: 87-99, illus. KNIPLING, B. F., GJULUN, C. M., and YATES, W. W. 1943. A NEW OIL-EMULSION MOSQUITO LARVICIDE. U.S. Bur. Ent. and Plant Quar. E-587, 4 pp. MCDUFFIE, W. C, SHARP, J. F., CROSS, H. F., and others. 1949. THE EFFECTIVENESS OF PREHATCHING TREATMENTS FOR THE CONTROL OF ARCTIC MOSQUITOES. Mosquito News 9 : 51-56. MARSHALL, J. F. 1938. THE BRITISH MOSQUITOES. .341 pp., iUus. London. MATHESON, R. 1944. HANDBOOK OF THE MOSQUITOES OF NORTH AMERICA. 314 PP., IUUS. Ithaca, N.Y. NATIONAL DEFENSE RESEARCH COMMITTEE. 1945. DEVELOPMENT OF AN EXHAUST DDT AEJROSOL GENEnjATOR FOE THE % TON, 4 X 4 TRUCK ("JEEP") . OSRD No. 6301, NRC Insect Control No. 139. 41 pp., illus. NATVIG, L. R. 1948. NORSK ENTOMOLOGISK TIDSSKRIFT. SUP. I. CONTRIBUTIONS TO THE KNOWLEDGE OF THE DANISH AND FENNOSCANDIAN MOSQUITOES. CULI- ciNi. 567 pp. Oslo. THE MOSQUITOES OF ALASKA 85
(88) NIELSEN, E. T., and GRèVE, H. 1950. STUDIES ON THE SWARMING HABITS OF MOSQUITOES AND OTHER NEMA- TOCERA. Bul. Ent. Res. 41: 227-258, illus. (89) PETROF, I. 1900. POPULATION, RESOURCES, ETC., OF ALASKA. [FROM U.S. CENSUS REPORT OF 1880.] In Compilation of Narratives of Explorations in Alaska. 56th Cong.. Ist Sess., Senate Rpt. No. 1023. 85« pp., illus. Wash., D.C. (90) PRATT, R. L. 1949. WEATHER AND ALASKAN INSECTS. Off. of the Quartermaster Gen., Mil. Planning Div., Res. and Devlpmt. Branch, Environmental Sect. Climatic Res. Lab. Rpt. No. 156. 25 pp., illus. (91) RAFFERTT, J. J. 1900. FROM PORT VALDEZ TO COPPER RIVER, DOWN THAT RIVER, THENCE TO PRINCE WILLIAM SOUND. In Compilation of Narratives of Explorations in Alaska. 56th Cong., 1st Sess., Senate Rpt. No. 1023. 856 pp., illus. Wash., D.C. (92) RALET, T. G. 1947. CALIFORNIA GROUND THERMAL AiaiOSOL GENERATOR. MoSquitO NewS 7 : 58-63, illus. (93) 1952. THE PLUMBER'S NIGHTMARE, KING SIZE. Mosquito News 12: 141-144, illus. (94) RAYMOND, C. P. 1900. EECONNOISSANCE OP THE TUKON RIVER, 1869. In Compilation of Nar- ratives of Explorations in Alaska. 56th Cong., 1st Sess., Senate Rpt. No. 1023. 856 pp., illus. Wash., D.C. (95) Ross, E. S., and ROBERTS, H. R. 1943. MOSQUITO ATLAS, PT. I. THE NEARCTIC ANOPHELES ; IMPORTANT MALARIA VECTORS OF THE AMERICAS AND AEDES AEGTPTI, CULEX QUINQUEFASCI- ATUS. 44 pp., illus. Phila. (96) ROTH, A. R., YATES, W. W., and LINDQUIST, A. W. 1947. PEELIMINABT STUDIES OF LAEVICIDES ON SNOW-WATEE MOSQUITOES. Mosquito News 7: 154-156. (97) SMITH, C. N., GILBERT, I. H., and GOUCK, H. K. 1958. USE OF INSECT REPELLENTS. U.S. Agr. Res. Serv. ARS-33-26, rev., 6 pp. (98) STAGE, H. H. 1951. MOSQUITO CONTROL AGENCIES IN THE UNITED STATES. Mosquito News 11: 8-22, illus. (99) and CHAMBERLIN, J. C. 1945. ABUNDANCE AND FLIGHT HABITS OF CERTAIN ALASKAN MOSQUITOES, AS DETERMINED BY MEANS OF A EOTABY-TYPE TRAP. Mosqulto News 5 : &-16, illus. (100) GJULLIN, C. M., and YATES, W. W. 1937. FLIGHT RANGE AND LONGEVITY OF FL0ODWATER MOSQUITOES IN THE LOWER COLUMBIA RIVER VALLEY. Jour. Bcon. Ent. 30: 940-945, illus. (101) STEFANSSON, V. 1921. THE FRIENDLY ARCTIC. THE STORY OF FIVE YEARS IN POLAR REGIONS. 784 pp., illus. N.Y. (102) STIVERS, J. O. 1956. PHOSPHATE USE IN CALIFORNIA MOSQUITO CONTROL. MOSqultO NewS 16 : 87-91. (102a) STONE, A., KNIGHT, K. L., and STARCKE, H. 1959. A SYNOPTIC CATALOG OF THE MOSQUITOES OF THE WORLD (DÍPTERA, cuLiciDAE). 358 pp. Entomological Society of America, College Park, Md. (103) TRAVIS, B. V., APPLEWHITE, K. H., FRITH, G. R., and GOLDSMITH, .T. B. 1953. ADDITIONAL OBSERVATIONS ON THE CONTROL OF MOSQXHTO LARVAE IN ALASKA WITH DDT. Mosqulto News 13: 1-3. (104) APPLEWHITE, K. H., and SMITH, N. 1950. CONTROL OF MOSQUITO LARVAE IN ALASKA WITH DDT. JoUr. Econ. Ent. 43: 350-353. (105) GJULLIN, C. M., BLANTON, F. S., and others. 1949. PEEHATCHING TREATMENT FOR THE CONTROL OF AEDES IN ALASKA. Mosquito News 9: 42-48. 86 AGR. HANDBOOK 18 2, U.S. DEPT. OF AGRICULTURE
(106) TuLLOCH, G. S. 1034. MOSQUITO INVESTIGATIONS IN ALASKA.. Psyche 41: 201-210, illus. (107) UNITED STATES DEPARTMENT OF AGRICULTURE, ENTOMOLOGY RESEARCH BRANCH. 1955. INSECTICIDES AND REPELLENTS FOE THE CONTROL OF INSECTS OF MEDICAL IMPORTANCE TO THE ARMED FORCES. U.S. Dept. Agr. Cir. 977, 91 pp., illus. (108) VANNOTE, R. L. 19.54. EXPERIENCE WITH GRANULAR INSECTICIDES FOR MOSQUITO CONTROL IN EASTERN UNITED STATES. N..J. Mosquito Extermin. Assoc. Proc. 41, pp. 123-126. (109) VOCKEROTH, J. R. 1954. NOTES ON THE IDENTITIES AND DISTRIBUTIONS OF AEDES SPECIES OF NORTH- ERN CANADA, WITH A KEY TO THE FEMALES (DÍPTERA : CULICIDAE) . Canad. Ent. 86: 241-255. (110) WASHBURN, G. E. 1954. EXPERIENCE WITH GRANULAR INSECTICIDES IN THE WESTERN UNITED STATES. N.J. Mosquito Extermin. Assoc. Proc. 41, pp. 118-123. (111) 1956. GRANULAR PESTICIDES IN CALIFORNIA MOSQUITO CONTROL. MosquitO News 16:104-105. (112) AVHITEHEAD, F. E. 1951. RICE FIELD MOSQUITO CONTROL BY PELLET-BORNE INSECTICIDES. Ark. Agr. Expt. Sta. Bui. 511, .30 pp. (113) WILSON, C. S. 1950. AEROSOL SPRAY UNITS FOR CONTROL OF BITING INSECTS. MOSQUITO NCWS 10: 51-54, illus. (114) 1951. CONTROL OF ALASKAN BITING INSECTS. U.S. Pub. Health Rpts. 66: 917-922. (115) WRAY, F. C. 1946. SIX GENERATIONS OF CULEX PIPIENS WITHOUT A BLOOD MEAL. MOSQULTO News 6 : 71-72, illus. (116) YATES, W. AV.. and GJULLIN, C. M. 1947. PRE-HATCHING APPLICATIONS OF DDT LARVICIDES UN FLOODWATER AEDES MOSQUITOES. Mosquito News 7 : 4-6. Appendix
ipQ' is£ is:' OCEAM = cr'^ x>^ ALASKA
• Aedes conununis
"(..-■ r J'^^'*»
c A ^,
MAP 1.—Distribution of Aedes communis. 87 88 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE
'<^- >"'■ >tO- W IS2- P*«- ,W 140- 13b- ur' 138-\ (2Í.'\ 120-\ 1 ■^ry'^'^^^'^^^^^ ALASKA
A ?■■' \ ,_-^ ^° " ° ° K 5 /(R A N 0 t ( >U .-»• I / ) / ^^"""^-^^ ' ^'\î • Aedes punctor
"^/fecW^'l^. -^ ' ^." V^f «.^p ^-»-/^ - - ^?îll^c;( "L-^ A-i, • ' / R^ '"■""'"'" wP^ i???C- ';:^„ ' ^iw- y---- ^ ^ ^ j^^s^y'^ ^^tiji^^^ ^~"^i *, ^^^^C^ '^"'^Ç^/'^Zil^^^^ "^ ^^^^^^--l /WLkonW, ^"S^'f, ■fOi/A-oU ^^ _ M,«.-*^ ^^a D,iu ''^'^i-Ci ^ u i Á/~^J k. ....:7ri W »ló.t-rl^y^VS '".'^v/ ^^"^'-"^ ■^■"- / ^h '"•-£ flby^^"" wSsit ' ^^ t J ^^ -——^ / ^ ' ^ if CuikjJJr *• '\ V/? ^^^—---/'^^ 'i^ M JL>—irtf^^tr"'^"'" ' - Iff J --«■ ^^ÜJA ^¡J^ P A C/ ^' ^ ° ^ Í ' '' ""^^^tó "^ ' ^^fc /"^^x^r^ '^ ^AS ,- J 1)?LAí^ Jin'-''' , r , , .0. '"■ '"■ "•■ MAP 2.—Distribution of Aeies punctor. THE MOSQUITOES OF ALASKA 89 i^o' \3t- ij;- izt- I;í,- o r c.^ /v ^cr'' X>'. ALASKA s / R A N G t Aedes implicatus IT ,oV zjRiyi - I KLAS^/J '^ V O"- .\-> . \% I F I C 0 C E p A MAP 3.—Distribution of Aedes implicatus. 90 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE 11,0- I'...- rs." («6- i^,.- 140- Lit ;j;- ,;.- i¿..- ijr,- ,.^S^2^ OCEAN N>"'" 'V^T^ ^V->^ ALASKA / ^J A'^\"> ./ ' ■"Cr' X .'■ \ ^^^"''"»^S/IR/VNOÍ >l. ...- \ / ^^- î\î \ /■ cA ',1 ■ Aedes cinereus - .'"'i-"-'( >■''■'- A diantaeus • pullatus ^^^^ fc^^^'S- Vb^"L ..,,,,^?î^t '-'-'-- .'' ,■ ^^' '• /^ >TiCwCt- ^^>^^\-f- 6/,' ' "'''In- .'*" ^ I... ;;.'.- ^ '»ru )- ^^Y^^^^""^r^'-"-^^^^"^^ "'"'^Y^^,,, ^ït >.>^ , la* // ' M't-iiv*:^ ■?■ \.^Y '"'-* ^^ r^V X ,- —^ í ■\LíT!|%J-,- '■; . bO> "^ Y r^ /iM^hX^ ■:;% ' Si'Xg^^ -^—^6^^ / •'**■ -i^fer /n- ^¿^TT*"^ \55^^ ° ^ r-^/^ 1 i 1 1 ^_ j_ - 1 MAP 4.—Distribution of Ae(?;e.s cinereus, diantaeus, and pullatus. THE MOSQUITOES OF ALASKA. 91 MAP 5.—Distribution of Aedes excrucian^ and intrudeuii. 92 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE ^ „f.- bO* PSh' ps:- Ifc8* 14..- IfcO- 136- JJ2- i:a* iza' izo- ^^--^l'^^^ OCEAN ' sPf"''x^/\ ^ ^V-^ ALASKA /■""tsl ^^^J^R^^: ° " ° 0 K 5 /(R A N 0 t tU ^w * . I • Aedes pionips \;/.'^'-^-".^.b^^ A Stimulans V^r^'X^^- 7^--V ^^ Li?^ ,.,,..>.^r^j^^^.\''''' ^l^llliaCtt V^-^^ "V^^ J -w "/ ^"° "'""" 0. J i™_^ 'Xy«'''^^ ^"~^ ■ VC/!^" ^^^'''""~\:qÉí%r" '3 ^ w XTi^y^^'// r- ^ *'"l¿a'^'-^^'^T^W.T^ / «^o y ) A~,.k// ,' ..;;W\^ />.--j ■^'""fiJß- ^<^ f J^~^^ -^ "N '"' "W^i^fe"''' > ■ vr -^ !5'^^?^'"^ /^' ^^'33l^V^.-.. \_ ^\2/P^^/^ ^^" ■% vt f ^.^ Cl.ll,",t¡um/^ , ^êœ"^XTí 1 rai-.SS ~-.> (^»-^^ <^ , ,c> f Í /I A/ "' M ü*^/ .^-->¿í*^í> p^ rfl'>íá-' /^Si>T^ ^ ^ , \tó\f/ /»°"-' 1 1 1 1 1 ■"' MAP 6.—Distribution of Aedes pionips and Stimulans. THE MOSQUITOES OF ALASKA 93 ^^ '^- ~ -"•'.....J'' ^i^ ^;£ 1^^ T ^i— \iZ- IZS- l¿'.' 120' .sBC^'^^ ALASKA K> / ',...Z^ -•>f/k''^r^> ' " ° ° « 5 /R * M 0 t 1 >|, . b*- ^ ^' ^^"^"^ ■'^^v ' ii° ^ ■ 1 •* c-o \ ■/;'''-'-'',,_,.,,,bk__ • Aedes cataphylla ■ flavescens A hexodontus "/ %^s^:::: i-^'!^."°!^i^C^~4 ^ riparius ^^'^To^ S //^^Ji3--- u^^,.^rl.. -■;; 1 ^°OA,ß V^^£J ^ 7» ^*=«aO'ii- "/^ -■ (T (—--^ ^3^ T^"" ^ L^¿^--' ■ SiCr ^M^pu-^"^^ v. T y iJ3r^ c1ii/(j. p\civi.~o \ -' \^ jj:^'3^^-'.rl,, \ ^Ji^sj^^<--^ f_^i o.»..,k.~/^ ^ e-v/'^^^ ^^ U^ V~*^ j( ^ N/^ ^Vl^C^f N-^ Iff ■'-'- ''*'" )fc\i'/^'^ V^ P A f ' ^ ' "^ " ' ' .. "°'"'"H^Ä^-r"" y^-^^ly fi^ ^\^^\' ^yjT^^^v^ VÖÄ * ^^ j—VILAI^ a>'-'-"- .S2' !*«■ 1*4- MAP 7.—Distribution of Aeies cataphylla, flavescens, hexodontus, and riparius. 94 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE .!«• ibO- If.»,' (52* \^ff l.t- 1*0- I3b- 122- 128- r24' 120' \ \ \ V ^_^¿^Jn_^ OCEAN .^B^'" C^ ^\K->^ ALASKA / ' '" " vvL -.^J?^^^ ; ^ ,■?/„' \ .^_ ° " ° 0 K s /(R A s 0 t >!, ^w \ / " A / ^^■"^-~- ' '.\° V /-'•■'/,'. ,.„.}>i-, • Aedes fitchii . ': „.. .!^.; A impiger i^^^^^^r^rr: \J7^ ,..,.^^:¡¡^^-\-'-''-^- - w •■"/ ^fc,*° "'-".s.,< r^y íí?'^''^ c--^' ' C^, ^,...... ■ »-'Z^^ -p>'^t:!::^ W^- '^'i """O^,,! - w ijj^^'^ ^ / -i^^ / / Í*-',*^ -¡**7 ^^.-7 ^tf^'^Wt^''« V ^/'Z^S, \3 /^ I '-'"U S/ i_'~^^ / V Vi 1] .>-^^ c .^ ', „y^^^-V "0 \/i-^rf*—■'^^^ ^isT" " I > u- / "vA t^ y ^ ' Y aP ""''■^cjfy^- ■ - '\2¡ \ß 'P^"^ "^ J^^^S"^^^'^^ \ ) /¿y^h'i^j' ''^—^-^$x'/'^X' -6^^^J^^iL v-^ ,„.,„. .••'^" Ch«ha^lL, -»Jv^lövV ^?*- ' ""'^^C**» f JT t^ S // ^,-' ■ v'^y ^^•^/>••' ■•" y^ P^^ ..c-^'^ '" '""^^^¿s'^r y—>4^1>^ MAP 8.—Distribution of Aedes fitchii and impiger. THE MOSQUITOES OF ALASKA 95 ALASKA Tundfo.bor« rock.A ic. CZ) M.r,.rbor..l(or„, HH Coaltar for«st O Aedes aboriginis ■ canadensis ** decticus nigripes Culex territans MAP 9.—Distribution of Aedes aboriginis, canadensis^ decticus, nigripes, and Culex territans. 96 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE MAP 10.—Distribution of Anoplieles earlei and Culiseta tnoraitans. THE MOSQUITOES OF ALASKA 97 M" i-H- '¿••' l-il' i : '^ 'SlL '0°' IS-- IS;- 1-S- I«-- CO- uf —T h ' • —1 ALASKA ^w \ I'-' \ /-^-->! " ° ° K 3 /(R . N 0 t |, • Culiseta impatiens '^/fti:!^ .^|...- .'^' v' Vf'''4i,p ^-^-/^ _;L^'TïitÎir,r 'V^'A.Í, ; V'- ,..'•''"' ^.."I'-- 1"^'i»^^-^^^^-^» K,,, '^'^ "^'Mi:^^^^-'---'''^'^*^,^ '-n , w* /~\) .. i/f^ "•i'Ä<^ ^ '-^Y '—\ ^^*\!î r^ _V^ *"' V V'"°7\\ * ^''"/ ^^ I ^ ^ /*^^-^ j-^ ^ ^"^^^^^eC*^*Ch-ft-a^lL- "•»M^>V^^ '^T'»- / v*" J" y_S"T"'* ' '''""''>JV^j\'j^ î^ 6=.o-..f;^W^l^^^^ / ^<^ tyrr^~i'^ /^-{s^ ^^^ p A c / ^ ' f ° ^ ^ ^ ^ """^^^tó.r ^—s ¿v~'' .5^"^ *^** ^''í?^ ' y''^Z>"3>7r*-^ *^^Ä ^ V r^^TjfJk.y^'^^'^-^ ,1^1 ^ 1 t, tL- n»- isa- i*a- J**- „O- 116- IJ.-- MAP 11.—Distribution of Culiseta impatiens. 98 AGR. HANDBOOK 182, U.S. DEPT. OF AGRICULTURE "" I-.'- I„W- lo,' IbO* 156' I5Ï* 1*8' I*".' ihO- iJb' IJ2* ire* IZ*.' IZO* ^^'""/C^ ^VT^TT*-"*^ ALASKA 0 K s /^R ft N 0 ^ tU '"• ., 1 Xj.\ m Culiseta alaskaensis Ir.- \ I y^""" üSÍ^^^ ^ incidens -' LIT ,..,^^^;;^--\---'--- ^ particeps "/ ^"^'^-- ^^ J¿Í|5^^^ Hin.nJjjg"^ \^ ^"íí/> (M^^ MT / r / ^^% " /<^ f A <:'''' '' ° '^ ^ * N ^tóüP'J'' /-^k-'"iy ^ ^^^"w j—iJj£Ar^*^" ' ' "•■ MAP 12.^Distribution of Ctiliseta alaskaensis, incidens, and particeps. U.S. GOVERNMENT PRINTING OFFICE : 1961 O— 551810