Predaceous Insects, Spiders, and Mites of Arkansas Cotton Fields

By W. H. WHITCOMB and K. BELL

AGRICULTURAL EXPERIMENT STATION Division of Agriculture University of Arkansas, Fayetteville

JUNE, 1964 BULLETIN 690 CONTENTS Page Introduction ______3 Partial Review of Literature______1______4 Methods ______6 Major and Minor Pests of Arkansas Cotton______8 Boll Weevil ______8 Bollworms ______9 Spider Mites ______10 Thrips ______11 Cotton Fleahopper ______12 Tarnished Plant Bug ______12 Cotton Aphid ______13 Cotton Leafworm ______14 The Predaceous Insects ______14 Dragonflies and Damselflies—Odonata______15 Praying Mantids and Grasshoppers—Orthoptera ------17 Thrips—Thysanoptera ______18 Lacewings, Owlflies, and Antiions—Neuroptera ______18 True Bugs—Hemiptera______20 Beetles—Coleoptera ______25 Flies—Diptera ______31 Ants and Wasps—Hymenoptera ______35 The Spiders ______40 The Predaceous Mites ------50 Predation on Bollworm E g g s______52 Experiments with Bollworm Eggs, 1962 ______52 Experiments with Bollworm Eggs, 1963 ______56 Hibernation______59 Source of Predators ______65 Natural Enemies of Predators______71 Other Predators ______71 Parasites ------72 Predators and Insecticides ______75 Summary ______77 Literature Cited ______79 Colloquial Names and Their Scientific Equivalents, as Used in the Text ______83 Acknowledgments ______84

COVER PICTURE Shown on the cover is a wolf spider, Lycosa rabida Walck., a predator of the bollworm moth.

Agricultural Experiment Station, University of Arkansas Division of Agriculture, Fayetteville. John W. White, vice-president for agriculture; E. M. Cralley, director. DPL3M664 Predaceous Insects, Spiders, and Mites of Arkansas Cotton Fields

By W. H. WHITCOMB and K. BELL Department of Entomology

Cotton is attacked by several important insect pests, which may be killed or suppressed by predators and parasites. The predator rapidly kills and eats many victims, while the parasite continues feeding on one host over a prolonged period of time. The objectives of this investigation were to inventory the predators present in the Arkansas cotton field, to elucidate the predator-prey relationship, and to judge the relative importance of prominent predators of major cotton pests. Moreover, factors affecting the decrease or increase of predator populations were investigated where possible. Approximately 600 species of predators representing 45 families of insects, 19 families of spiders, and 4 families of mites were found associated with cotton. The study was not limited to enemies of cotton pests; some of the species fed on other predators. The importance of several predators of major cotton insect pests has been underestimated. Ants are the most outstanding of the hitherto underrated predators. These ubiquitous insects are often mentioned as possible enemies of insect pests, but their great importance as predators is seldom recognized. Other underrated predators range from dragonflies that attack bollworm moths, Heliothis zea (Boddie), in flight, and longhorn grasshoppers that eat bollworm eggs, to jumping spiders that also feed on bollworm eggs. Evidence is overwhelming that predation frequently prevents outbreaks of bollworms, aphids, and spider mites in cotton. Preda- tion contributes significantly toward preventing excessive increases of insect pest populations. Under normal field conditions, 4 A r k a n s a s E x p e r im e n t S t a t io n , Bu l l e t in 690 if one species of predator is absent, others may take its place. However, if there has been a widespread and continued catastro- phe, such as drought or misuse of insecticides, this is no longer possible and reproduction of the insect pest species may continue unabated until starvation or disease intervenes. Unless corrective measures are taken, the prolonged absence of predators in the cotton field may be reflected at harvest time in marked reductions in crop yield. The nature of the surrounding areas influences both the kind and the number of predators present in a cotton field. The prox- imity of a plant host of the preferred prey of a given predator apparently increases the likelihood that the predator will be numerous in the field. A cotton patch in a deep forest has a different predator population than a cotton field bordered by hundreds of acres of corn. The absence of accepted common names for predaceous insects has handicapped the writing of this publication. Of neces- sity, there has been more widespread use of scientific names than is desirable. Where colloquial names are in general usage, they are first mentioned together with their scientific names and then are used freely. A list of colloquial names and their scientific equivalents is given at the end of this bulletin.

Partial Review of Literature

In 1856, in a discussion of insects beneficial to cotton, Glover (43) recognized many of the predators that are still considered important. Comstock (28), in his report on cotton insects of 1879, described these predators in more precise detail and discussed many more. Ashmead’s (5) study, in 1894-1895, is especially noteworthy because he paid particular attention to many hymenopterous predators that had been overlooked previously. The predators of the bollworm were first discussed extensively by Quaint- ance and Brues (77) in their bulletin on the bollworm. The predators of the boll weevil, Anthonomus grandis Boheman, were investigated by Cook (30) and by Hunter and Hinds (50). Modern research on cotton field predators began with studies on the effect of calcium arsenate on predators by Smith and Fon- tenot (84), on the fate of bollworm eggs in the field by Fletcher and Thomas (37), and on factors influencing bollworm populations by Ewing and Ivy (35). The last paper included the number of bollworm eggs consumed by various predators in the laboratory P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 5 and the effect of an increase in aphids on predator consumption of bollworm eggs. Destruction of predators by organic insecticides spurred a renewed interest in these beneficial insects, led by the work of Newsom and Smith (73). Other reports included field and laboratory studies by Campbell and Hutchins (25), surveys by R. C. Gaines (39, 40), observations on the effect of Systox (demeton) by Ahmed, et al. (3), studies on the insidious flower bug by Ig- linsky and Rainwater (52), and data on predators reported by Lincoln and Leigh (67). Harries and Valcarce (45), van den Bosch, et al. (90), Burke (23), Stern, et al. (85), and others have studied the specificity of insecticides to various predators. Life histories of individual cotton field predators include the life cycles of common damsel bugs (Nabidae) by Garman and Jewett (42) ; the biologies of the six-spotted thrips, Scolothrips sexmaculatus (Pergande), and of the black hunter, Leptothrips mali (Fitch), by Bailey (7, 8) ; the extensive investigations of the biology of Orius insidiosus (Say) by Barber (12) ; the life histories of three species of Chrysopa by Burke and Martin (24) ; and the biologies of the soft-winged flower beetles, Collops balteatus Le Conte and C. vittatus (Say), by Walker (91) and of C. vittatus by Nielson and Henderson (74). The relationship of predatory and injurious insects in Arizona cotton fields was discussed by Wene and Sheets (93). Spiders of the cotton field have been discussed by Kagan (61) and by Whitcomb, et al. (97). Hambleton (44), in his report of Heliothis virescens (Fabr.) as a pest of cotton in Peru, stressed the importance of its natural enemies and pointed out changes in cropping practices that af- fected their abundance. Wille (99) discussed the effect of organic insecticides on both predator and pest populations. Beingolea (13), Lamas (64), Simon (81), and Martin-Ravines (70) have found new predators, studied their life histories as well as those of better known predators, and used this knowledge to facilitate control of several cotton field pests. The work of Szumkowski (87, 88) in Venezuela deals especially with coccinellids, including rearing and extensive field observations. Wiesmann (98), Ahmed (2), Hassanein (47), and others have investigated various phases of the predator situation on cotton in Egypt, including feeding observations, life history studies, and selective toxicity of various insecticides. 6 A r k a n s a s E x p e r i m e n t S t a t i o n , B u l l e t i n 690

Methods This investigation required a wide range of techniques, each adapted to a particular phase of the study. In many cases, these will be discussed in the chapters that deal with special phases of predator research. Observation in the field, however, was the keynote of the entire project. Hundreds of hours were spent examining individual plants or observing the movements of the predators. The center of investigations was in the Arkansas River bottom seven miles southwest of Morrilton, where both insecticide- treated and untreated cotton fields were available, and included a one-acre field that had not received insecticide since the first planting to cotton four years earlier. Woods and short grass pastures were nearby. Other cultivated crops in the immediate area included corn, sorghum, soybeans, small grain, and alfalfa. Other experiments and observations were made in all cotton- growing areas of the state. Many of the trials conducted at Hope, Warren, McGehee, Kelso, Varner, Pine Bluff, Altheimer, Poca- hontas, and Fayetteville were as intensive as those at Morrilton but were of shorter duration. For general survey, 25, 50, or 100 plants were examined separately, beginning with a quick look at the whole plant, followed by a leaf-by-leaf and bract-by-bract search from the terminal to the soil surface. For sweeping, a 15-inch California-type net was used. In certain cases, sampling was done by a backpack vacuum apparatus as recommended by Dietrick (31) in 1961. Many feeding records were taken in the course of general survey; others, however, required special studies. Quick work with the net was necessary to capture wasps, robber flies, and dragonflies before their prey was destroyed or lost. Predation on bollworm eggs was investigated by field observations of eggs attached to cotton leaves with egg albumen. All types of counts and observations were taken at various times of day. Many of the most interesting observations were made at night or in the early morning hours. A sportsman’s lamp worn on the forehead aided in the night studies, especially in collecting wolf spiders in the cotton field. The authors used three methods for specifically sampling the fauna found on or near the ground. The first consisted of direct observation of the soil surface, both in the drill row and between the plants. In the second method, the ground stratum P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 7 was sampled by means of pitfall traps that were a modification of the type employed by Hensley, et al. (48). Each consisted of a buried metal sleeve supporting a quart jar. The jar ring was soldered to a half-inch rim that rested on the sleeve. A metal shield above excluded rain and debris. This construction per- mitted emptying the trap with minor disturbance to the soil. The traps were set directly in the drill rows. In the third method, trash collected from between the cotton rows was placed in a modified Berlese funnel consisting of a covered metal funnel 18 inches across with a screen to hold the trash. The specimens fell into a jar of 95 percent alcohol. Malaise traps constructed according to the design of Townes (89) were used for sampling populations of flying insects. These were tentlike structures of fine screen, with open sides through which the insects flew. Once inside, the insects collided with large baffles in the center of the structure and worked their way up- ward into a collecting apparatus at the top. These traps were excellent for capturing wasps and flies, and were useful for collecting other insects as well. However, it was necessary to keep the traps free of both web-weaving and vagrant spiders. In all laboratory feeding tests, predators were given as natural conditions as possible. A modification of the technique of Simpson and Burkhardt (82) was used. A glass vial of water in which a cotton terminal was inserted was placed in an ice cream container covered with the lid of a Petri dish. Bollworm eggs were attached to a leaf with egg albumen. Bollworm larvae were placed on leaves and were allowed to crawl about and feed as desired. Observations were made daily. 8 A r k a n s a s E x p e r i m e n t S t a t i o n , B u l l e t i n 690 MAJOR AND MINOR PESTS OF ARKANSAS COTTON This discussion of cotton field pests includes boll weevil,1 bollworm,2 spider mites,3 thrips,4 cotton fleahopper,5 tarnished plant bug,6 cotton aphid,7 and cotton leafworm.8 The latter two are included even though they have not been major pests in Arkansas for several years, because they sometimes influence the predator situation. Pink bollworm” is not included, since it has not occurred in sufficient numbers in the state for predator studies.

Boll Weevil The boll weevil is not native to the cotton belt of the United States. It was first found in the southernmost part of Texas in 1892. According to Isely and Baerg (60), the boll weevil first reached the southwestern corner of Arkansas in 1906, and by 1916 it had become established in all of the cotton-producing counties in the state except for the northern tier. By 1924, as pointed out by Isely (56), the loss due to the boll weevil exceeded the total value of any other Arkansas crop with the possible exception of corn. The greatest damage caused by the boll weevil results from the destruction of squares and the resulting loss of bolls. When the boll weevils have destroyed most of the squares, they attack bolls. Small bolls so attacked will be shed; one or more locks of cotton may be destroyed in larger bolls. Loss from the boll weevil varies from year to year. Damage may be especially serious in years of heavy infestation and abundant moisture. Thus, Lincoln and Leigh (67) found that only in such years did control of the boll weevil in bottomland tests give significant yield increases. Also, important geographic vari- ations in infestations exist. According to graphs published by Boyer, et al. (19), infestations are lower in the northern section of the Delta than in either the middle or southern section. There are usually much lower infestations in north Mississippi County than in Lee or Desha Counties. The effect of favorable hibernation sites upon local occurrence of weevils is also noticeable. According to Lincoln and Leigh (67), good, well-drained hiberna-

1Anthonomus grandis Boheman. 2Heliothis zea (Boddie). 8Tetranychus spp. 4Frankliniella jusca (Hinds) and F. tritici (Fitch). 5Psallus seriatus (Reuter). 6Lygus lineolaris (Beauvois). 7Aphis gossypii Glover. 8Alabama argillacea (Huebner). 9Pectinophora gossypiella (Saunders). P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 9

tion quarters contribute to maximum winter survival, which often leads to heavy early-season populations. The winter is passed as an adult in leaf trash on the ground. Percentage of survival is low; even 15 percent alive after hibernation is considered high. Emergence from hibernation may continue from March until well into July. Weevil-punctured squares may be found as soon as the first squares are one-third grown. At summer temperatures and with ample rainfall, infestations rise steadily during the fruiting period of the cotton plant. Lincoln, et al. (66) found this rate of increase to be approximately 2.5-fold weekly. During the cotton-growing season, control of the boll weevil by its natural enemies appears to be of little consequence. At times, hymenopterous parasites, especially Bracon mellitor Say, Heterolaccus hunteri (Crawford), and Aliolus curculionis (Fitch), destroy quite a few boll weevils. Birds, such as the purple martin, Progne subis subis (Linn.), destroy many adults in late-season migration. Ants kill some boll weevil grubs. Drag- onflies, clerids, assassin bugs, and spiders capture some adult weevils. One species of longhorn grasshopper, Orchelimum vulgare Harris, has been observed feeding on the boll weevil in the field. During hibernation, natural enemies may be much more important. Ground beetles are active in the trash during the winter and have been observed feeding on the boll weevil. Spiders of the family Lycosidae are also active, especially Lycosa gulosa W alck., L. punctulata Hentz, and Trochosa avara Keyserling. All of these spiders have fed on the boll weevil in the laboratory. Several species of the genus Cicurina of the family Agelenidae are particularly active during the winter, but very little is known of their feeding habits. Bollworms The bollworm, Heliotkis zea (Boddie), is nearly equal to the boll weevil in its importance as a cotton pest. The tobacco bud- w orm , H. viresoens (Fabr.), is much less abundant. Larvae of these two species cannot be separated with the naked eye, and both damage cotton in the same manner. Small larvae tend to feed first in the terminals and then in the squares. There is normally no measurable economic loss resulting from damage to the terminals and squares. Larger larvae, particularly later in the season, can cause much boll damage. A 10 A r k a n s a s E x p e r i m e n t S t a t i o n , B u l l e t i n 690 quantity of fiber is actually consumed, and other fiber is stained by the larval feces. Entrance holes in the boll allow both bacteria and fungi to enter, causing boll rots. Bollworms hibernate as pupae in the soil. Moths first emerge in late March and continue their emergence until June and possibly later. Eggs are first found in early-season legumes, such as crimson clover, vetch, and alfalfa. Later, overwintering moths lay their eggs on tomatoes and corn whorls. Moths from the first generation appear in early June, and it is at this time that the first eggs appear on cotton, even though the plant may not be fruiting. Later broods of the first generation and moths of succeeding generations lay more eggs as the season advances. The number of eggs fluctuates, partially in proportion to the number of moths flying and partially due to unknown factors. By the end of June, it is virtually impossible to distinguish one generation from another. Predators and parasites reduce the number of bollworms. They feed on the eggs, destroy both small and large larvae, attack the pupae in the soil, and capture large numbers of moths. If the population of predators is greatly decreased in a field for any cause, a bollworm outbreak is likely to occur. Scarcity of predators in nearby fields, drought, and parasites of predators can diminish predator populations in the cotton field and cause bollworm outbreaks. One factor frequently encountered is the use of insecticides. Repeated applications may lower the populations of almost all predators to the vanishing point. For this reason, the boll weevil is indirectly responsible for much of the bollworm problem, since insecticides applied to control boll weevil inadvertently lessen the number of bollworm predators.

Spider Mites Spider mites that attack cotton in Arkansas include the carmine spider mite,10 the desert spider mite,11 and the two-spotted spider mite.12 The latter is generally the most difficult to control. Eggs of the spider mites hatch in four days in the summer; larval and nymphal stages require a total of approximately six days. The male matures at least one day before the female. The most important injury caused by spider mites is to the foliage. At first, yellowish spots occur on the leaf, followed by a reddening of the entire leaf. If the infestation continues, leaves 10Tetranychus dnnabarinus (Boisduval). n T. desertorum Banks. 12 T. urticae Koch [T. telarius (L inn.)] Pre da to rs o f A r k a n s a s Cot t o n F ie l d s 11

dry up and are shed. Bolls are shed following extreme defoliation, and the entire plant may be killed. One species of spider mite was reported by Chaney (26) to overwinter in field borders, principally on Rubus species. Over- wintering can be expected to occur within the field if suitable undisturbed vegetative growth is present. Some authors report that small numbers survive land preparation and planting and infest seedling cotton. Although light populations of spider mites are scattered throughout the field, until 15 years ago outbreaks occurred only in dry weather and were largely confined to spots around stumps and along field margins. As pointed out by Lincoln and Leigh (67) and by Boyer and Bell (18), spider mite infestations have become more general and widespread following the widespread use of organic insecticides. The cause of these higher levels of spider mite infestations appears to be the destruction of their natural enemies, especially predaceous mites, the six-spotted thrips, and possibly a lady beetle [Stethorus punctum (Le Conte)]. Thrips Several species of thrips attack cotton in Arkansas. The tobacco thrips, Frankliniella fusca, is usually the dominant species on young plants, with the flower thrips, F. tritici, second in importance. Occasionally Sericothrips variabilis (Beach) is present in numbers, but this is a single generation species that may appear later than Frankliniella species. When cotton seedlings first appear above ground, they are attacked by thrips migrating from legumes such as white clover, bur clover, crimson clover, and alfalfa, and from small grains and weeds. During the next month or six weeks, one or two generations of thrips may develop. After that, populations drop to a low level. The population of the flower thrips increases later in the season in blossoms; it does no damage there, but it serves as food for predators. According to Newsom, et al. (72), the tobacco thrips overwinters in legumes, especially white clover. According to Watts (92), the flower thrips overwinters in plants that remain green, especially members of the mustard family and small grains. According to the results of several years’ experiments by Lincoln and Leigh (67), the control of thrips rarely improves the earliness, total yield, or stand of cotton in Arkansas. 12 Ar k a n s a s Exp er im en t St a t io n , Bu l l e t in 690

Thrips, however, are extremely important as prey of the insidious flower bug (Orius insidiosus), of nymphs of several other Hemiptera, of lady beetles, and of other predators.

Cotton Fleahopper The cotton fleahopper is a true bug that feeds on the juices of buds and of the tender parts of many plants, including cotton. There are three stages in its life cycle: egg, nymph, and adult, all of which may occur on cotton. Eggs are laid in weeds in mid- summer, late summer, and the fall. In southern Arkansas and neighboring states, goat weed, Croton spp., is probably the most attractive weed host. The cotton fleahopper overwinters as an egg, and the newly hatched nymphs appear on the weeds in the spring. The adults may move to cotton in June or July. The feeding of the cotton fleahopper on small cotton squares causes them to blast (to turn dark brown and dry up). Cotton yields may be reduced if populations of cotton fleahopper are heavy. In Arkansas, infestations are seldom serious enough to warrant the use of insecticide. Cotton fleahoppers supply important food for many predators. The fleahoppers appear in cotton at a time when predators are migrating into cotton from winter grains and other spring- time hosts; thrips have generally disappeared, and prey is in short supply. The egg of the cotton fleahopper is well protected from predators by being buried in plant tissue, but the other stages in its life cycle are very much exposed. Isely (57) observed that a big-eyed bug, Geocoris punctipes (Say), feeds freely on the cotton fleahopper and other plant bugs. The authors have often observed damsel bugs (Nabis spp.), big-eyed bugs, nymphs of Sinea spinipes (Herrich-Schaeffer), and even the insidious flower bug with first or second instar fleahopper nymphs on their beaks. Fleahopper nymphs also appear to be among the preferred prey of adult Lebia analis Dej. Some immature jumping spiders, especially Metaphid- ippus galathea (Walck.), feed on fleahoppers. Several other predators, both spiders and insects, depend on this prey. In many cases, the presence of the cotton fleahopper may make their survival possible. Tarnished Plant Bug The tarnished plant bug is the only species of Lygus that is ever abundant in Arkansas cotton fields. Other members of this genus are quite destructive to cotton in the Far West. Damage caused by these bugs is similar to that caused by the cotton flea- P red ators o f Ar k a n s a s Cot to n F ie l d s 13 hopper. Under Arkansas conditions, the tarnished plant bug mul- tiplies on spring hosts, especially vetch, alfalfa, and certain weeds, and then may move into cotton. In the fall, there is a population build-up on fall legumes and on fleabane, Erigeron spp. Unlike the cotton fleahopper, the tarnished plant bug overwinters as an adult. As in the case of the cotton fleahopper, tarnished plant bug nymphs serve as prey for many predators, including big-eyed bugs, nabids, and the insidious flower bug. Adult tarnished plant bugs serve as prey for larger predators including the reduviids, [Sinea, spinipes, Zelus exsanguis (Stal), Z. cervicalis (Stal), and Z. socius (Uhler)] and the stink bug, Podisus maculiventris (Say). Spider predators include the lynx spiders, Oxyopes salticus Hentz and Peucetia viridans (Hentz), and the jumping spiders, Metaphidippus galathea, P h idippus variegatus (Lucas), and Hentzia spp. Cotton Aphid The cotton aphid is a world-wide pest of cotton, cucurbits, and other crops. It has been reported attacking cotton wherever this crop is grown. This insect damages the cotton plant by sucking the sap, thus causing distortion and discoloration of the leaves, and by excreting honeydew which interferes with the function of the leaf stomata. A sooty mold growing on the honeydew further interferes with leaf function and even stains the lint in opened bolls. According to Kring (63), the cotton aphid overwinters as an egg on catalpa, Catalpa bignonioides Walt., and on rose of Sharon, Hibiscus syriacus Linn. On secondary hosts such as cotton or melon it reproduces rapidly. Isely (58) found that it may develop from birth to maturity in four days. Paddock (75) recorded 51 generations in 12 months in Texas. In spite of its unbelievable capacity for reproduction, this aphid is normally controlled by its natural enemies. If something reduces the number of parasites or predators, an aphid outbreak may occur. Even cool temperatures, such as 68° F., which slow down predator reproduction but allow aphid reproduction at a high rate, may cause a flare-up in aphid population. Destruction of predators by insecticides may result in damage by aphids. Small numbers of aphids in the cotton field serve as food for predators and may not be completely undesirable. Too many aphids, on the other hand, may attract predators away from other prey, such as bollworms. It is possible, also, that honeydew from large numbers of aphids may attract bollworm moths. 14 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690 Cotton Leafworm The cotton leafworm is a tropical insect that does not overwinter in the United States but migrates northward from the tropics almost every year, arriving in southern Texas and spread- ing northward from there. Until recent years, this pest was frequently very destructive. At the present time, it is seldom abundant in Arkansas before cotton begins to mature. This insect is largely a foliage feeder. Heavy infestations of cotton leafworm quickly defoliate a field. Only as a last resort do they feed on squares or bolls. If an attack occurs after the bolls open, bits of trash may lower the value of the lint. The bluish-green, saucer-shaped eggs are usually laid on the lower surfaces of the leaves. The larvae normally leave the plants only when there is a shortage of food or when they are accidentally knocked off. They pupate in corners of leaves in flimsy cocoons. If the foliage has been stripped, the larvae sometimes pupate in weeds on the edges of a field. Predators are seldom effective against cotton leafworm in this country. The sudden deposition of tens of thousands of eggs, which hatch in a little over two days, and the rapid growth rate of the larvae completely inundate natural control. Numerous predators and parasites attack cotton leafworm eggs and larvae; however, before predator and parasite reproduction takes place and effective populations are reached, the cotton leafworms have ma- tured and migrated.

THE PREDACEOUS INSECTS Eight orders of predaceous insects, including 45 families, are known to be present in Arkansas cotton fields. Further observations and new techniques will almost certainly disclose the presence of other families and even other orders of insect predators. In the case of many dipterous families, more must be known about their biology to determine whether they are carnivorous or not. In some cases, it is very hard to draw the line between predation and parasitism. The predators listed in the succeeding pages have been found in Arkansas cotton fields. The ecology of each family and the habits of the most common species are discussed. P re da to rs o f A r k a n s a s Co t t o n F ie l d s 15 Dragonflies and Damselflies—Odonata This group of predators has been completely underrated except in rare instances. Not only do the Odonata feed on insects of economic importance, but since they may come to cotton fields from great distances, they are somewhat less exposed to insecticides than many other predators. However, they may rest on treated foliage, and large numbers have been found dead between the rows following the use of methyl parathion. Aeshnidae Anax juriius (Drury) Epiaeschna heros (Fabr.) Anax longipes Hagen Members of the genus Anax are large, strong dragonflies. A. junius is the large, high-flying dragonfly with a bluish tinge that is so abundant in Arkansas cotton fields from the middle of August until the middle of September. The prey may vary from mosquitoes to noctuid moths. Club-tailed dragonflies—Gomphidae Progomphus obscurus Gomphus submedianus (Rambur) Williamson Erpetogomphus designatus Gomphus hybridus Williamson Hagen Gomphus lividus Selys Gomphus lentulus Needham Gomphids are less conspicuous than other dragonflies. They alight for a longer time and do less darting about. The yellowish or greenish stripes on the thorax make an almost perfect camou- flage. Nevertheless, careful observation will disclose one or two species present in most Arkansas cotton fields. They feed on a wide variety of flying insects. One species of Gomphus with large, spiny forelegs was observed capturing nymphalid butterflies. Libellulidae Tetragoneuria cynosura Plathemis lydia (Drury) (Say) Sympetrum ambiguum Perithemis tenera (Say) (Rambur) Celithemis elisa (Hagen) Erythemis simplicicollis Celithemis eponina (Drury) (Say) Celithemis fasciata Kirby Pachydiplax longipennis Libellula flavida Rambur (Burmeister) Libellula incesta Hagen Tramea lacerata Hagen Libellula luctuosa Burmeister Pantala flavescens (Fabr.) Libellula pulchella Drury Pantala hymenaea (Say) Libellula vibrans Fabr. 16 A r k a n s a s E x p e r im e n t St a t io n , Bu l l e t in 690 Members of this family are by far the most numerous dragonflies in Arkansas cotton fields. They are seen darting up and down the cotton rows, even far from water. Pachydiplax longipennis is the most abundant species. It has often been observed feeding on mosquitoes, Psorophora confinnis (L.-A.) and others, has been captured while attacking adult green lacewings, and undoubtedly feeds on many other insects. The green jacket dragonfly, Erythemis simplicicollis, is by far the most beneficial species. As reported by Bell and Whitcomb (15), it feeds freely on several noctuid moths, including the bollworm moth, the cabbage looper [Trichoplusia ni (Huebner)], and the cotton leafworm. However, the prey of this species is not confined to the Lepidoptera; at times, most of the prey consists of other insects. Feeding takes place freely from about 9 A.M. until nightfall. In the late afternoon as moths begin flying, hundreds of green jacket dragonflies can be observed zigzagging back and forth high over a cotton field and capturing moths on the wing. One of the white tails (Plathemis lydia), a small yellow dragonfly (Perithemis tenera), and Pantala hymenaea are all very common species.

Damselflies—Coenagrionidae Argia apicalis (Say) Enallagma divagans Selys Argia moesta (Hagen) Ischnura posita (Hagen) Argia violacea (Hagen) Anomalagrion hastatum Enallagma signatum (Hagen) (Say) Most of these damselflies are feeble fliers and, when alight- ing, hold the body horizontal and the wings together over the back. They can be found in a variety of habitats, including almost every cotton field in Arkansas. They feed freely on nematocerate Dip- tera and other small insects.

Broad-winged damselflies—Agrionidae Agrion maculatum Beauvois Hetaerina americana (Fabr.) These are large damselflies with gradually narrowing wings. They normally occur along wooded streams and occasionally stray into cotton fields, especially in the hill section of the state. P redat or s o f A r k a n s a s Co t t o n F ie l d s 17 Praying Mantids and Grasshoppers—Orthoptera Members of this order are large and often conspicuous; many are economically important. It is somewhat surprising that their feeding habits are not well understood. The only wholly carnivorous family is the Mantidae. According to Gangwere (41), neither the Phasmatidae nor the Tetrigidae feed on animal material. Most of the other families have some members that are aggressively predaceous. Praying mantids—Mantidae Stagmomantis Carolina (Johannson) Stagmomantis Carolina is a voracious predator. It has been taken while feeding on the boll weevil, the bollworm moth, and other cotton pests. Unfortunately, it is seldom abundant in the cotton field. It usually is found near the border of the field, close to high bushes and perennial weeds. Longhorn grasshoppers—Tettigoniidae Orchelimum vulgare Harris Conocephalus fasciatus (De Geer) Most longhorn grasshoppers are plant feeders; some can be quite destructive. However, several have been observed to be predaceous on other insects. Both of the species mentioned above fed on bollworm eggs in the laboratory. One adult of Conocephalus fasciatus ate a maximum of 75 of these eggs in one 48-hour period. An adult of Orchelimum vulgare ate 25 eggs in 41 minutes. A nymph of an undetermined species was observed feeding on bollworm eggs in the field. In each case, it carefully consumed all trace of the egg but did not damage or feed on the foliage. On one occasion, O. vulgare was observed feeding on a boll weevil in a cotton field. Crickets— Gryllidae Oecanthus nigricornis Walker All crickets are somewhat omnivorous in their feeding habits; in particular, tree crickets of the genus Oecanthus are known to be predaceous at times. Other species of Oecanthus are present in Arkansas cotton fields, but this group has not yet been carefully collected in cotton. Tree cricket adults fed freely on bollworm eggs in the laboratory. 18 A r k a n s a s E x p e r im e n t St a t io n , Bu l l e t in 690 Thrips—Thysanoptera Representatives of both suborders of thrips are predators. The most important predaceous thrips is a member of a family thought to consist mostly of plant feeders. Little is known of the feeding habits of many thrips; as more information is obtained, more thrips may be found to be predaceous. More species of thrips already considered predaceous will be found to be present in Arkansas cotton fields as the survey of predators continues. Banded-winged thrips—Aeolothripidae Aeolothrips fasciatus (Linn.) So far as is known, all members of this family are beneficial, since they feed upon plant-feeding thrips, small insects, and mites. In Arkansas, Aeolothrips fasciatus appears early in the season and disappears with the advent of hot weather. It has been observed feeding on flower thrips larvae and adults. Other species of Aeolothrips are probably present in the cotton field but have not yet been taken. Thripidae Scolothrips sexmaculatus (Pergande)13 The six-spotted thrips is considered to be one of the major predators in Arkansas cotton fields. Lincoln et al. (68)14 credit it with controlling spider mites on cotton in Arkansas. There are other factors, including predaceous mites, which help prevent outbreaks of spider mites, but the six-spotted thrips is undoubtedly one of the principal factors. According to Bailey (7), the entire life cycle of this thrips is passed on the host plant. Like many plant-feeding thrips, it inserts its eggs in plant tissue. Phlaeothripidae Leptothrips mali (Fitch) The black hunter is occasionally found in an Arkansas cotton field. It prefers woods and orchards. Bailey (8) reported that it feeds on small insects, mites, and insect eggs. Lacewings, Owlflies, and Antlions— Neuroptera Although the adults in this order are fragile insects, the larvae are strictly predaceous and extremely voracious. Certain families in this order are limited to aquatic situations; however, five families are found in the cotton field. Very few insects are as efficient predators as the green lacewings. 13According to Bailey (9), the six-spotted thrips that is known as Scolothrips sexmaculatus (Pergande) may be a complex of three or more species, including S. sexmaculatus. 14 The Sericothrips variabilis (Beach) reported in this article was later found to be Scolothrips sexmaculatus. Pred a t or s of A r k a n s a s Cotton F ie l d s 19

Mantispids—Mantispidae Climaciella brunnea (Say) Larvae of most species of mantispids are predaceous on eggs of wolf spiders, as shown by Bristowe (22). Adults feed on flies and other insects. According to Brauer (20, 21), large numbers of eggs are laid, but only a few larvae find the mother wolf spiders and their egg sacs. Mantispids are found in cotton fields all over Arkansas but are somewhat uncommon and are of little importance. Owlflies—Ascalaphidae Ululodes macleayana Van der Weele Owlflies are somewhat uncommon in Arkansas cotton fields. Both adults and larvae are predaceous. According to McClendon (71), eggs are laid on a branch or twig, and a larva similar to that of an antilon hatches and drops to the ground. It does not dig a pit but hides in a natural depression waiting for small insects. The adult feeds on small flies and similar insects; little is known of the prey of the larva. Antiions—Myrmeleontidae Dendroleon obsoletum (Say) Hesperoleon abdominalis (Say) In Arkansas, antiions are sometimes abundant in sandy fields but are less common in fields of heavier soil. Almost every farm boy in Arkansas is familiar with the broad, flattened larva, which he calls a “doodle bug” and entices out of its lair with a straw. The “doodle bug” is found at the center of a funnel-shaped depression, which serves as a pitfall trap to capture ants, the usual prey of this larva. Little is known of the feeding habits of the adults. Green lacewings—Chrysopidae Chrysopa plorabunda Fitch Chrysopa nigricornis Chrysopa oculata Say Burmeister Chrysopa rufilabris Chrysopa Intacta Navas Burmeister Chrysopa harrisii Fitch Chrysopa quadripunctata Burmeister This is the most important family of neuropterous insects in Arkansas, particularly in cotton fields but also in fields of other row crops, orchards, and forests. This is not true in aquatic situations nor in barren, sandy areas. The larvae have been observed consuming large numbers of lepidopterous eggs, including those of the bollworm, cotton leafworm, cabbage looper, many 20 A r k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690 species of aphids, and other soft-bodied insects. In the case of Chrysopa oculata, the adult, as well as the larva, is predaceous. The two most common species of Chrysopa in cotton fields in Arkansas appear to be C. plorabunda and C. oculata,. Next in importance are C. rufilabris, C. harrisii, C. intacta, and C. nign- cornis. Any one of these species, however, may be the dominant species in a given field at any one time. In trials conducted in 1958 in the laboratory at Morrilton, larvae of C. oculata ate as many as 42 bollworm eggs per day. According to Burke and Martin (24), C. plorabunda, C. oculata, and C. rufilabris complete two molts during the active or feeding period and complete the last molt inside the cocoon. Frequently, the green lacewing eggs, which are characteristically placed on a hyaline gelatinous stalk and are easily seen, are abundant in cotton when both adults and larvae of green lacewings are scarce. As indicated by Lincoln and Leigh (67), this may be because adults are sometimes more active at night or may indicate excessive mortality of active forms. Brown lacewings—Hemerobiidae Hemerobius humulinus Linn. Micromus subanticus Micromus posticus (Walker) (Walker) Micromus variolosus Hagen Both adults and larvae of the brown lacewings are predaceous. The larvae are very inconspicuous and may remain hidden when not actually seeking prey. In Arkansas cotton fields, the larvae have been taken feeding on aphids, whitefly larvae (Aley- rodidae), and other small insects. They are much less abundant than the green lacewings. The species most often taken is Mi- cromus posticus. True Bugs— Hemiptera The predaceous bugs include many of the best known predators in the cotton field. Several families are strictly predaceous; certain families consisting mostly of plant feeders have genera or subfamilies that are predaceous. A total of nine families of predaceous bugs have been taken in the cotton field. Flower bugs—Anthocoridae Orius insidiosus (Say) Cardiastethics assimilis Orius tristicolor (White) (Reuter) While the flower bugs or minute pirate bugs are small and inconspicuous, they are voracious predators of aphids, plant bugs, P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 21

Figure 1. The insidious flower bug, Orius insidiosus (Say). thrips, mites, lepidopterous eggs, and other arthropods. The insidious flower bug (Figure 1) is an excellent predator of bollworm eggs and first instar larvae. O. tristicolor is found most frequently in the western counties of Arkansas, and further west it re- places the insidious flower bug. Plant bugs—Miridae Deraeocoris nebulosus (Uhler) This is the family to which the cotton fleahopper, the tarnished plant bug, and many other destructive species belong. Many species of the subfamily Deraeocorinae are predaceous. The genus Deraeocoris is well represented in Arkansas, but the species are found more often on trees and bushes than in row crops. The only species taken on cotton, D. nebulosus, has been found in both the field and greenhouse feeding on the cotton aphid. In Peru, other mirids such as Rhinacloa aricana Carvalho are among the most important predators of the cotton field. Ambush bugs—Phymatidae Phymata fasciata (Gray) Phymata pennsylvanica Handlirsch This is a family of very efficient and effective predators (Figure 2). Unfortunately, they are comparatively uncommon in the cotton field. A few individuals are found in cotton terminals late in the season. On the other hand, these insects are very abundant in flower heads, such as those of goldenrod and many composites. They easily capture skippers, moths, or other insects many times their size. 22 A r k a n s a s E x p e r i m e n t S t a t i o n , B u l l e t i n 690

Figure 2. An ambush bug, Phymata sp. Assassin bugs—Reduviidae Melanolestes picipes Zelus socius (Uhler) (Herrich-Schaeffer) Zelus bilobus Say Rasahus hamatus (Fabr.) Sinea diadema (Fabr.) Sirthenea carinata (Fabr.) Sinea spinipes (Herrich- Apiomerus crassipes (Fabr.) Schaeffer) Fitchia aptera Stal Pselliopus cinctus (Fabr.) Repipta taurus (Fabr.) Pselliopus barberi Davis Atrachelus cinereus (Fabr.) Pselliopus latifasciatus Zelus exsanguis (Stal) Barber Zelus cervicalis (Stal) Arilus cristatus (Linn.) This is one of the most important families of predaceous insects. Assassin bugs are found attacking larvae or adults of many pest species. In Arkansas cotton fields, however, the Reduviidae are generally of less importance than many other groups. Species of the genus Zelus are sometimes abundant on cotton plants in Arkansas and feed freely on eggs and larvae of Lepidoptera and other orders. Z. exsanguis and Z. cervicalis were taken feeding on bollworm larvae at Morrilton, and Z. socius was taken feeding on bollworm larvae near Hope. Z. exsanguis was also taken feeding on the cotton leafworm and the cabbage looper. Sinea diadema and S. spinipes were both taken feeding on the boll weevil at Hope, P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 23

Figure 3. The wheel bug, Arilus cristatus (Linn.) McGehee, and Morrilton. However, these two species are far more often taken feeding on the lady beetles Hippodamia convergens Guerin-Meneville and Coleomegilla maculata (De Geer) and on the spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber. Arilus cristatus, the wheel bug (Figure 3), is an excellent predator on the bollworm, particularly on the larger larvae and adults. However, it is seldom numerous enough in cotton fields to be of economic value. Thread-legged bugs—Ploiariidae Emesaya brevipennis (Say) Metapterus fraternus (Say) Members of this family are only occasionally found in Arkan- sas cotton fields. Emesaya brevipennis has been observed feeding on several species of small moths. Damsel bugs—Nabidae Nobis capsiformis Germar Nabis roseipennis Reuter Nobis alternatus (Parshley) Nabis sordidus Reuter Nabis ferns (Linn.) Nabis deceptivus Harris Damsel bugs are efficient and effective predators. They feed on a wide range of prey including plant bugs, leafhoppers, aphids, and lepidopterous eggs and larvae. They occasionally feed on big- eyed bugs, the insidious flower bug, and other small beneficial insects. They rival the insidious flower bug in the number of 24 A r k a n s a s E x p e r im e n t S t a t io n , B u l l e t in 690 bollworm eggs consumed by an individual per day. They appear to be the most efficient predators against first and second instar bollworms. There is a tendency for populations to vary sharply from week to week. P art of this variation appears to be due to a parasite and is discussed in the section on Natural Enemies of Predators. Nabis ferns, N. altematus, and N. capsiformis are particularly common in Arkansas cotton fields. Stilt bugs—Berytidae Jalysus spinosus (Say) Jalysus wickhami Van Duzee Members of this small family have been reported to feed on lepidopterous eggs. They are common, but not abundant, in Ar- kansas cotton fields. Lygaeid bugs—Lygaeidae Geocoris punctipes (Say) Hypogeocoris imperialis Geocoris uliginosus (Say) (Distant) Hypogeocoris piceus (Say) This is the family to which the chinch bug, Blissus leucopterus (Say), and many other very destructive pests belong. However, the big-eyed bug and its close relatives are predaceous, feeding on aphids, plant bugs, and the eggs and young larvae of various moths including the bollworm and cotton leafworm. These predators are more consistently present than most other species in untreated cotton fields in Arkansas. Stink bugs—Pentatomidae Podisus maculiventris (Say) Perillus bioculatus (Fabr.) Stiretrus anchorago (Fabr.) Most stink bugs are plant feeders. However, members of the subfamily Asopinae are predaceous; they may be differentiated from the others by the first segment of the beak which is short, thick, and free. Other species of this subfamily are probably present in the cotton field but have not yet been taken. The spined soldier bug, Podisus maculiventris, is an abundant and valuable predator against large bollworms. It is not unusual in the field to see two individuals feeding at opposite ends of the same fifth instar larva. The spined soldier bug feeds on a wide range of prey, including Coleoptera larvae. Stiretrus anchorage has not been observed feeding, although it is not rare in the cotton field. Rolston (79) reports this insect as predaceous on eggplant tortoise beetle, Nuzonia pallidula (Boheman). Perillus bioculatus is seen less often on the cotton plant than is Stiretrus anchorage. P r e d a t o r s o f A r k a n s a s Co t t o n F ie l d s 25 Beetles—Coleoptera More species of predators present belonged to the Coleoptera than to any other order. However, these represented comparatively few families. More families may prove to be predaceous as more is known about their feeding habits. Within certain of the large families, such as the ground beetles, there was as much divergence in habits as is commonly found among suborders. Tiger beetles—Cicindelidae Megacephala virginica Cicindela cuprascens Le Conte (Linn.) Cicindela punctulata Oliv. Megacephala Carolina (Linn.) Cicindela splendida Hentz Cicindela sexguttata Fabr. The two genera of tiger beetles found in cotton fields differ in both appearance and habits. The large, dark-green Megacephala are nocturnal and were found to be abundant after dark in almost all fields. The diurnal Cicindela were most active on hot, cloud- less days. These beetles are smaller, more brightly colored, and have longer legs. They were most abundant on the sandier soils. Both genera appear to feed on various prey. Megacephala virginica was observed feeding on an unidentified noctuid moth. The larvae of both genera are predaceous and live in vertical burrows in the soil. Ground beetles—Carabidae Carabus sylvosus Say Evarthrus seximpressus Calosoma sayi Dej. (Le Conte) Calosoma externum Say Evarthrus sodalis Le Conte Calosoma scrutator Fabr. Agonum punctiformis (Say) Calosoma marginale Casey Agonum rubripes (Le Conte) Calosoma willcoxi Le Conte Harpalus caliginosus (Fabr.) Pasimachus elongatus Harpalus pennsylvanicus Le Conte De Geer Pasimachus punctulatus Hald. Harpalus compar Le Conte Pasimachus depressus Fabr. Harpalus vagans Le Conte Scarites subterraneus Fabr. Harpalus faunus Say Scarites substriatus Hald. Harpalus nitidulus Chaud. Clivina bipustulata (Fabr.) Harpalus gravis Le Conte Bembidion intermedium Cratacanthus dubius (Kirby) (Beauvois) Pterostichus chalcites (Say) Anisodactylus rusticus (Say) Pterostichus permundus Say Anisodactylus dulcicollis Evarthrus sigillatus (Say) (Laf.) 26 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690

Anisodactylus furvus Chlaenius tricolor Dej. Le Conte Colliuris pennsylvanicus Anisodactylus harpaloides (Linn.) (Laf.) Lehia viridis Say Anisodactylus sanctaecrucis Lebia marginicollis Dej. (Fabr.) Lebia viridipennis Dej. Stenolophus ochropezus Lebia analis Dej. (Say) Lebia abdominalis Chaud. Stenolophus dissimilis Dej. Lebia pumila Dej. Agonoderus lineola (Fabr.) Callida punctata Le Conte Agonoderus comma (Fabr.) Callida decora (Fabr.) Agonoderus lecontei Chaud. Callida viridipennis (Say) Dicaelus purpuratus Bon. Galeritula bicolor (Drury) Dicaelus sculptilis Say Galeritula janus (Fabr.) Badister elegans Le Conte Brachinus ballistarius Chlaenius tomentosus (Say) Le Conte Chlaenius sericeus Forst. Brachinus perplexus Dej. Chlaenius memoralis Say Brachinus cordicollis Dej. Chlaenius aestivus Say Brachinus americanus Chlaenius laticollis Say Le Conte Chlaenius erythropus Germar Brachinus fumans (Fabr.) The habits of the members of this large family are extremely varied. Species such as Carabus sylvosus and Calosoma willcoxi are found in cotton fields only near wooded areas, while Ptero- stichus chalcites and Harpalus pennsylvanicus are found in nearly every cotton field in the state that has not been heavily treated with insecticide. Feeding habits vary even more. Species belong- ing to such genera as Calosoma and Lebia are voraciously predaceous, while less than half the food of Harpalus pennsylvanicus is of animal origin, and predatism in some species of Clivina is almost nonexistent. The great variability in the ground beetles is further demonstrated in the subterranean habits of Scarites, the surface-searching of Chlaenius and Galeritula, the tree-climbing of Calosoma scrutator, and the almost completely arboreal nature of adult Lebia. The differences are nowhere better demonstrated than in the complete disappearance of Calosoma where a small amount of insecticide is used and the persistence of Ptero- stichus chalcites populations in cotton in spite of repeated use of chlorinated hydrocarbon insecticides. The importance of this family in the cotton field is greatly underestimated. This may result partially from the subterranean habits of most larvae, many of which feed on other insect larvae in the soil, and partially from the nocturnal habits of the non- P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 27 subterranean carabid larvae and of most ground beetle adults. Many mature carabids patrol the soil surface and attack pest species that fall to the ground. During outbreaks of lepidopterous larvae such as Alabama argillacea, several species of ground beetles, including Calosoma sayi and C. externum, can sometimes be observed feeding on the larvae even in daylight. When bollworms are abundant in cotton, adult C. scrutator can sometimes be seen at night halfway up the cotton plant feeding on bollworm moths or large larvae. Of the ground beetles found in the cotton field, those in the genus Lebia are of particular interest. They are abundant on cotton foliage both day and night everywhere that cotton is grown in Arkansas. So far as is known, they do not reproduce in cotton fields but migrate from soybean fields and possibly from corn fields. The eggs of Lebia analis are laid in the soil at the base of soybean plants, and a cocoon of soil is formed around each egg. The larvae hatch after six days, but the food of the first and second instars is still unknown. In the laboratory, larger larvae consume larvae and pupae of the bean leaf beetle, Cerotoma tri- furcata (Foerster), and of the southern corn rootworm, Diabrotica undecimpunctata howardi, and pupate in the soil. The adults attack fleahoppers, plant bugs, and many other soft-bodied insects. They eat many kinds of insect eggs, including their own. Lebia analis adults consumed an average of six bollworm eggs a day in the laboratory (Table 1). Table 1. Number of Heliothis zea Eggs Consumed By Adults of Lebia analis

Total no. of Av. no. of eggs S pecim en No. of days eggs consumed consumed per day

1 18 71 4.0 2 21 128 6.0 3 21 138 6.5 4 8 30 3.7 5 18 131 7.3

6 18 130 7.2 7 13 82 6.3 8 14 83 6.0 9 18 128 7.1 10 13 81 6.2 Average, all sp ecim en s 6.03

Rove beetles—Staphylinidae Although approximately ten species of this family have been taken in Arkansas cotton fields, none has yet been identified. Classification of these insects is particularly difficult. Rove beetles form a large group of thousands of species, but they are especially 28 A r k a n s a s E x p e r i m e n t S t a t io n , B u l l e t in 690 abundant in forested areas. The family is poorly represented in cotton fields. Many species in this family are active predators. One was observed by the senior author capturing a muscoid fly out of the air. Soldier beetles—Cantharidae Chauliognathus pennsylvani- Podabrus brunnicollis (Fabr.) cus De Geer Podabrus flavicollis Le Conte Chauliognathus marginatus Cantharis bilineatus Say Fabr. Silis latilobus Blatch. The soldier beetles are both herbivorous and carnivorous. Some are even serious plant pests. The larvae of many species feed on small insects on or in the soil. Balduf (11) reported that the adults of various species of Podabrus and Cantharis are common predators on plant lice. Sweetman (86) reported that the larvae of Chauliognathus pennsylvanicus were observed destroying large numbers of striped cucumber beetles, Acalymma vittata (Fabr.) Fireflies—Lampyridae Lucidota atra (Fabr.) Photinus pyralis (Linn.) Pyropyga minuta (Le Conte) Photuris versicolor Fabr. Photinus lineellus Le Conte Pyractomena dispersa Green The most outstanding characteristic of members of this family is their ability to produce light in all stages from egg to adult. Photuris versicolor is apparently the most abundant species of Lampyridae in Arkansas cotton fields. One small species, Pyropyga minuta, numerous in cotton, differs from most other fireflies by not producing light. Most larvae and the majority of female adult fireflies prey on snails. Eggs are laid in crevices in the soil. Sweetman (86) reported that after a long incubation, from 3 weeks to 2 months, the active and voracious larva hatches and seeks its prey. Upon finding a snail, it injects a substance that para- lyzes it. Soft-winged flower beetles—Melyridae Collops balteatus Le Conte Collops quadrimaculatus (Fabr.) Both the smaller Collops quadrimaculatus and the larger C. balteatus are quite abundant in Arkansas cotton fields. According to Walker (91), C. balteatus selected oviposition sites in hollow grass stems, cotton burs, partially decayed cotton stalks, and other similar places. According to the same author, the larvae of Collops spp. were usually found on the soil surface, not on the cotton foliage. C. balteatus is a well-known predator of bollworm eggs and young larvae. When feeding on bollworm eggs, this species seldom P redators of A r k a n s a s Cotton F ields 29 leaves any eggC. shell. quadrim aculatus refused to feed on bollworm eggs or larvae in the laboratory. Both species fed freely on cotton aphids.C. vitta tu s,reported by Walker (91) to be the most common species in Texas cotton fields, has not yet been found in Arkansas cotton. A closer investigation may reveal its presence, at least in Southwest Arkansas. Checkered beetles— Cleridae Cymatodera undulata Say Enoclerus lunatus Klug Cregya oculata Say Checkered beetles are very aggressive predators in both the larval and adult stages. Hunter and Pierce (51) reported that they feed on boll weevil larvae.Enoclerus lunatus, a medium-sized clerid found in both corn and cotton in Arkansas, was taken while feeding on a short-snouted weevil. Unfortunately, checkered bee tles are not common in Arkansas cotton fields. Lady beetles— Coccinellidae Hyperaspis binotata (Say) Hippodamia convergens Hyperaspis fimbriolata Guerin-Meneville Melsheimer Hippodamia glacialis (Fabr.) Stethorus punctum (Le Conte) Hippodamia tredecimpunctata Scymnus americanus Mulsant (Linn.) Scymnus fraternus Le Conte Coccinella novemnotata Scymnus hortensis Wingo Herbst Scymnus iowensis Casey Cycloneda munda (Say) Scymnus loewii Mulsant Cycloneda sanguinea (Linn.) Scymnus puncticollis Le ConteOlla abdominalis (Say) Scymnus rubricaudus Casey Neomysia pullata (Say) Scymnus terminatus Say Axion tripustulatum Delphastus pusillus (De Geer) (Le Conte) Exochomus marginipennis Coleomegilla maculata (Le Conte) (De Geer) Psyllobora vigintimaculata (Say) Twenty-four species of lady beetles or coccinellids have been found in Arkansas cotton fields. Not all of these are numerous; some have been taken only occasionally. The three most common of the larger lady beetles are the spottedColeomegilla lady beetle ( m aculata) (Figure 4), the convergent ladyHippodam beetle ia ( convergens), and the nine-spotted ladyCoccinella beetle novem ( notata) . Any one of these may be the dominant coccinellid in a particular cotton field at any given time. On the whole, the con vergent lady beetle is the most abundant species. Large populations of the spotted lady beetle tend to be found in cotton fields near 30 A r k a n s a s E x p e r im e n t S t a t io n , B u l l e t in 690

Figure 4. The spotted lady beetle, Coleomegilla maculata (De Geer). corn, sorghum, or Johnson grass. In Arkansas, Edwards (34) found that the eggs of this lady beetle hatched in 2 to 5 days, that the four stages of the larval period required 10 to 14 days, and that the pupal period lasted 3 to 5 days, for an average life cycle of only 25 days. The nine-spotted lady beetle was usually moderately abundant, but only occasionally was it the most abundant species. Cycloneda munda is often the dominant lady beetle in early legumes and small grains but has rarely been found abundant in cotton. C. sanguinea is very abundant in cotton fields in more southern areas but is seldom numerous in Arkansas cotton. All of these species have been observed feeding freely on lepidopterous eggs including those of bollworm, cotton leafworm, cabbage looper, fall armyworm [Spodoptera frugiperda (J. E. Smith)], yellow-striped armyworm (Prodenia ornithogalli Guenee), and others. Most have been captured while feeding on small bollworm larvae; they are also excellent aphid predators and feed freely on the cotton aphid. In feeding tests of the convergent lady beetle on one species of aphid, Myzus persicae (Sulzer), Roberts (78) found that 215 convergent lady beetle larvae had a theoretical consumption of 2,919 aphids per day, or a total of 87,599 aphids in 14 days. The larger species of the genus Scymnus are aphid predators; some of the smaller species feed on mites. Stethorus punctum is a voracious predator on mites. Pr ed a t o r s of Ar k a n sa s Co t t o n F iel ds 31 Blister beetles—Meloidae Lytta conferta (Say) Epicauta lemniscata (Fabr.) Epicauta atrata (Fabr.) Epicauta marginata (Fabr.) Epicauta cinerea (Foerster) Epicauta pennsylvanica Epicauta, fabricii (Le Conte) (De Geer) Epicauta funebris Horn These beetles are predaceous only in the larval stage. As adults, they are destructive pests in such crops as potatoes, tomatoes, alfalfa, beans, and beets. The larvae of most Arkansas species feed almost exclusively on grasshopper eggs (Acrididae). According to Horsfall (49), the life histories of five of the species mentioned above are quite closely correlated with the egg-laying habits of the differential grasshopper, Melanoplus differentialis (Thomas), and of the two-striped grasshopper, M. bivittatus (Say). Blister beetles deposit their eggs in tubular cavities in the soil. The young larva emerges from the egg mass, reaches the surface of the soil, and searches for a grasshopper egg pod. If successful, the blister beetle larva matures inside the egg pod. Since grasshoppers are only occasionally numerous in the cotton field, blister beetle larvae and adults are infrequently abundant in Arkansas cotton. Flies— Diptera The feeding habits of this order probably have more surprises for investigators than those of any other major group. The predaceous habits of the robber flies and syrphid flies, as well as the parasitic habits of the tachinids, are well-known, but dozens of small families of flies are largely predaceous. In the family An- thomyiidae, there are plant-feeding species and voracious predators in the same genus. Robber flies—Asilidae Psilocurus nudiusculus Loew Promachus fitchii Dizonias tristis (Walker) Osten Sacken Diogmites misellus Loew Promachus hinei Bromley Diogmites neoternata Bromley Mallophora acra Curran Diogmites platypterus Loew Mallophora clausicella Diogmites symmachus Loew Macquart Atomosia puella (Wiedemann) Mallophora orcina Atomosia sayi Johnson (Wiedemann) Promachus bastardii Nerax aestuans (Linn.) (Macquart) 32 Ark a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690 Nerax interruptus Proctacanthus rufus Williston (Macquart) Proctacanthella cacopilogus Nerax rufibarbis (Macquart) (Hine) Proctacanthus brevipennis Proctacanthella leucopogon (Wiedemann) (Williston) Proctacanthus milbertii Asilus spp. Macquart Robber flies are very abundant in cotton fields in all parts of the state. Probably the most common species is Promachus hinei. This medium-sized robber fly is most active on bright, sunny days. At night, it can be picked off the cotton foliage by hand. Its most common prey are Hymenoptera: at times honey bees or bumble bees, at other times Polistes spp., and at still other times sphecid wasps such as those of the genus Trypoxylon. P art of the prey be- longs to various orders, from Orthoptera to Lepidoptera, and includes the cotton leafworm moth. Diogmites symmachus (Figure 5) fed mostly on Hymenoptera in the cotton field, but in soybeans it fed most often on the three-cornered alfalfa hopper, Spissistilus festinus (Say). The large robber flies Proctacanthus milbertii and P. rufus are especially common in Southwest Arkansas. P. milbertii preys on similar insects to those fed on by Promachus hinei, but its prey is somewhat more varied. Honey bees, bumble bees, the cicada killer [Sphecius speciosus (Drury) ], and a large nymphalid butter- fly are typical prey of Proctacanthus rufus. In the cotton field, robber flies are usually destructive rather than beneficial, since 75 percent of their prey is hymenopterous. Nerax aestuans and N. interruptus are exceptions, since they prey largely on Orthoptera. Even in these cases, any benefit from robber fly activity appears to be of little importance. Mydas flies—Mydaeidae My das clavatus (Drury) These are large flies that resemble robber flies but have one more segment in the antennae than the true robber flies of the family Asilidae. The adults are predaceous on a variety of insects; the larvae occur in rotting wood. The adults of Mydas clavatus are found in almost all Arkansas cotton fields. They make a loud buzzing noise as they search for prey. Dance flies—Empididae Drapetis divergens Loew In this family, adults are almost all predaceous; larvae may be predaceous. The male usually offers prey to the female prior to mating. Each species of dance fly tends to have specific prey. In Pr ed a t o r s of Ark a n s a s Co tt o n F ie l d s 33

Figure 5. Robber fly, Diogmites symmachus Loew, feeding on rice stink bug, Oebalus pugnax (Fabr.)

Arkansas, the authors have noticed that several species tend to feed on other dance flies. The single species found in the cotton field has not been observed with prey. Long-legged flies—Dolichopodidae Pelastoneurus vagans Loew Condylostylus sipho (Say) Diaphorus leucostomus Loew Dolichopus alacer Diaphorus spectabilis Loew Van Duzee Condylostylus caudatus Dolichopus bifractus Loew (Wiedemann) Dolichopus ramifer Loew Condylostylus comatus Asyndetus sp. (Loew) 34 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690 These are very small, metallic-colored flies. Most members of this family are predatory in both the larval and adult stages. Ac- cording to Sweetman (86), mouth parts are adapted for crushing and lapping the blood of the prey. Long-legged flies are unusually numerous in Arkansas cotton fields, where they have been observed feeding on small, unidentified insects. Syrphid flies—Syrphidae Milesia virginiensis (Drury) Syrphus rectus Osten Sacken Toxomerus geminatus (Say) Syrphus torvus Osten Sacken Mesograpta boscii (Macquart) Platycheirus quadratus (Say) Mesograpta marginata (Say) Meromacrus acutus (Fabr.) Mesograpta polita (Say) Helophilus fasciatus Walker Aliograpta obliqua (Say) Eristalis (Eristalis) trans- Sphaerophoria cylindrica versus Wiedemann (Say) Eristalis (Eristalis) Sphaerophoria robusta Curran vinetorum (Fabr.) Metasyrphus americanus Xylota (Xylotomima) (Wiedemann) metallica Wiedemann Eupeodes volucris Tropidia albistylum Macquart Osten Sacken Syrphidae is one of the largest and best known families of the order Diptera. Many species are brightly colored and may be striped, spotted, or banded with yellow on a dark background. The adult syrphid flies are not predaceous but feed on nectar and pollen. The habits of the larvae (Figure 6) are considerably varied; some larvae even feed on plant bulbs and stems. A number of genera and many species prey on aphids and other soft-bodied insects. The eggs of the predaceous species are placed singly on cotton leaves or other foliage near their prey. After hatching, the slug- gish, slow-moving larvae begin consuming the eggs or young of their prey. One larva may destroy hundreds of aphids before it matures. There may be three or more generations of syrphid flies a year. Most species commonly overwinter as pupae. Bee flies—Bombyliidae Anthrax anale Say Villa alternata (Say) Anthrax argyropygus Villa fulvohirta (Wiedemann) Wiedemann Villa sinuosa (Wiedemann) Anthrax tigrinus (DeGeer) Spamopolius lherminierii Poecilanthrax lucifer (Fabr.) (Macquart) The adults of this family are mostly stout-bodied flies with dense hair. The adults are apparently not predaceous but are found on flowers or hovering over grass in open, sunny places. The larvae, Pr e d a t o r s o f Ar k a n sa s Co t t o n F iel ds 35

Figure 6. Syrphid fly larvae consuming aphids. so far as is known, are predaceous or parasitic on eggs of grasshoppers, hymenopterous larvae, caterpillars, and beetle grubs. Although adult bee flies are frequently found in Arkansas cotton fields, the larvae are rarely found. Sciomyzidae Dictya sp. According to Foote, et al. (38), the larvae of many species of Sciomyzidae feed on snails. More than 60 species have been reared on living or dead snails in a laboratory at Cornell University, Ithaca, N. Y. Both larval and adult sciomyzids are common in Ar- kansas cotton, but none of the species taken has yet been identified.

Ants and Wasps— Hymenoptera Predatory habits are more strongly developed in the Hymenop- tera than in most other orders of insects. There are several predaceous families. The great number of ants and their widespread distribution make them a factor that must not be overlooked. The extreme diversity of the many wasp species is quite surprising. At least three unrelated groups prey on spiders. While the paper- nest wasps, the potter wasps, and the solitary wasps of the genus Sphex feed on lepidopterous larvae, each group goes about it in a different way. The paper-nest wasps macerate their prey and roll 36 Ar k a n s a s Ex pe r im e n t St a t io n , Bu l l e t in 690 them into balls; the potter wasps paralyze their prey only partially; and the sphecid wasps completely paralyze their prey by stinging each nerve center. Ants—Formicidae Ponera trigona opacior Forel Iridomyrmex pruinosus analis Aphaenogaster lamellidens (Andre) Mayr Forelius foetidus (Buckley) Pheidole bicarinata Dorymyrmex pyramicus var. vinelandica Forel flavus McCook Pheidole dentata Mayr Tapinoma sessile (Say) Pheidole sitarches Wheeler Brachymyrmex depilis Emery Crematogaster ashmeadi Mayr Camponotus americanus Mayr Crematogaster clara Mayr Camponotus castaneus Crematogaster lineolata (Latreille) (Say) Camponotus ferrugineus Monomorium minimum (Fabr.) (Buckley) Camponotus pennsylvanicus Solenopsis geminata (Fabr.) (De Geer) Solenopsis xyloni McCook Paratrechina (Nylanderia) Solenopsis molesta (Say) spp. Leptothorax curvispinosus Prenolepis imparts (Say) Mayr Lasius neoniger Emery Leptothorax schaumi Roger Formica schaufussi dolosa Leptothorax pergandei Emery Wheeler Iridomyrmex pruinosus Formica (Neoformica) sp. (Roger) Representatives of four subfamilies of Formicidae have been found in Arkansas cotton fields. Most of these are predaceous at least part of the time. The subfamily Ponerinae, a primitive carnivorous group that does not collect honeydew, was represented by only one species, Ponera trigona opacior, which was found in cotton fields in very small colonies. The myrmicine ants, a large cosmopolitan group, includes some of the ants most commonly found in the cotton field, such as those in the genera Pheidole, Crematogaster, Monomorium, and Solenopsis. Workers of the little black ant, Monomorium minimum, have been taken in the act of killing a healthy fifth instar bollworm. In Arkansas, workers of the fire ant, Solenopsis geminata, have been observed killing boll weevil adults. The dolichoderine ants, which tend to be southern in distribution, include the genera Iridomyrmex, Forelius, Dorymyrmex, and Tapinoma. Iridomyrmex pruinosus has proven to be a regular predator on bollworm eggs in the field. The subfamily Formicinae is considered more northern in distribution but is well represented Pr ed a t o r s o f Ar k a n sa s Co t t o n F ie ld s 37 in Arkansas. The carpenter ants of the genus Camponotus are found in the cotton field, particularly on recently cleared land, but are seldom abundant; on the other hand, the genera Prenolepis and Lasius include species that are very important. Ants of the genus Paratrechina have been observed removing bollworm eggs from the cotton plant. Spider wasps—Pompilidae Pepsis elegans Lepeletier Poecilopompilus algidus Pepsis mildei Stal algidus (Smith) Priocnessus nebulosus Poecilopompilus interruptus (Dahlbom) interruptus (Say) Priocnemioides fulvicornis Tachypompilus ferrugineus (Cresson) ferrugineus (Say) Priocnemioides unifasciatus Anoplius aethiops (Cresson) unifasciatus (Say) Anoplius atrox (Dahlbom) Cryptocheilus attenuatum Anoplius bengtssoni (Regan) Banks Anoplius amethystinus Cryptocheilus terminatum atramentarius (Dahlbom) subopacum (Cresson) Anoplius americanus Dipogon papago anomalus americanus (Beauvois) Dreis. Anoplius bellicosus (Banks) Calicurgus hyalinatus Anoplius marginalis (Banks) alienatus (Smith) Anoplius relativus (Fox) Phanagenia bombycina Anoplius marginatus (Say) (Cresson) Anoplius subcylindricus Auplopus architectus (Say) (Banks) Ageniella agenioides (Fox) Anoplius ventralis (Banks) Ceropales femoralis Cresson Aporinellus fasciatus (Smith) Psorthaspis brimleyi Paracyphononyx funereus (Malloch) (Lepeletier) Sericopompilus apicalis (Say) Most wasps of the family Pompilidae provision their nests with spiders. These wasps may be distinguished from other wasps that prey on spiders by the long spiny legs. The hind femora extend beyond the tip of the abdomen. Many of these wasps search the surface of the soil in the cotton field for wolf spiders, fisher spiders, or funnel-web weavers. Others apparently search for specific orb weavers. Still others are less specific, gathering what prey is available. Pepsis elegans is a blue-black wasp, large for a wasp but smaller than most tarantula hawks, and has bright orange antennae. It is especially common in the cotton field. Tachypompilus ferrugineus ferrugineus is a reddish wasp frequently taken in the 38 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690

cotton field with wolf spiders, especially Lycosa helluo Walck., as prey. Members of this family cannot be considered beneficial, since all their prey are predators. L. rabida Walck., a spider that feeds on the bollworm moth, is attacked by at least one species of pompilid. Vespid wasps—Vespidae Vespula maculifrons Rygchium dorsale dorsale (Buysson) (Fabr.) Vespula maculata (Linn.) Rygchium foraminatum Vespula squamosa (Drury) foraminatum (Saussure) Polistes annularis (Linn.) Rygchium megaera Polistes exclamans Viereck (Lepeletier) Polistes fuscatus (Fabr.) Rygchium molestum Polistes hunteri Bequaert (Saussure) Polistes metricus Say Stenodynerus anormis (Say) Polistes rubiginosus Stenodynerus fundatiformis Lepeletier gonosceles Boheman Zethus spinipes spinipes Say Stenodynerus fulvipes Eumenes fraternus Say fulvipes (Saussure) Pseudodynerus quadrisectus Stenodynerus pedestris (Say) (Saussure) Monobia quadridens (Linn.) Stenodynerus vagus Rygchium annulatum arvense (Saussure) (Saussure) The species of this family that are found in the cotton field can be separated into two distinct groups: the social wasps, whose nest is a community consisting of a comb containing brood cells, and the solitary vespids, which construct individual nests. Both groups are predaceous. Although the feeding habits of the genus Vespula of the social wasps are not completely understood, these wasps are known to feed on lepidopterous larvae and other animal matter. The species of the genus Polistes provision their nests almost exclusively with lepidopterous larvae. They macerate the larvae and work them into balls which they carry to the nests. All six species found in Arkansas have been observed attacking the bollworm (Figure 7). Although Isely (55) reported P. metricus as the most common species of this genus in Northwest Arkansas, P. annularis is apparently the most important predator of fourth and fifth instar bollworms in most of Arkansas. The genera Zethus, Eumenes, Rygchium, and Stenodynerus of the solitary vespids provision their nests with whole lepidopterous larvae, which they have partially paralyzed. Eumenes attaches a clay, juglike nest to a twig, places the prey in the bottom, and suspends its own egg on a thread from the top. A detailed life history of various species of this genus was published by Isely (54). Pr ed a t o r s o f Ark a n s a s Co t t o n F ields 39

Figure 7. Polistes annularis (Linn.), a vespid wasp that preys on bollworm larvae. Sphecid wasps—Sphecidae Tachytes elongatus Cresson Sphex aureonotatus (Cam.) Tachytes pennsylvanicus Sphex femaldi Murray Banks Sphex harti Fernald Tachytes obscurus Cresson Sphex nigricans (Dahlbom) Tachytes austrinus Banks Sphex placidus (Smith) Tachysphex sp. Sphex procerus (Dahlbom) Larva analis Fabr. Sphex urnarius (Dahlbom) Trypoxylon clavatum Say Sceliphron caementarium Trypoxylon politum Say (Drury) Trypoxylon texense Saussure Chalybion californicum Chlorion ichneumoneum (Saussure) (Linn.) Zanysson fuscipes (Cresson) Chlorion pennsylvanicum Sphecius speciosus (Drury) (Linn.) Gorytes phaleratus Say Chlorion auripes Fernald Bicyrtes capnoptera Chlorion atratum (Lepeletier) (Handlirsch) Chlorion aerarium Patt. Bembix Carolina (Fabr.) Sphex arvensis (Dahlbom) Philanthus gibbosus (Fabr.) 40 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690

Cerceris bicornuta bicornuta Cerceris compacta Cresson Guer. Cerceris firma Cresson Cerceris clypeata Dahlbom This is a large family of predators with varied prey prefer- ences. Each group usually limits itself to one type of prey. The species of the tribe Tachytini provision their nests with Orthop- te ra ; one Tachytes wasp was taken in the cotton field with a red- legged grasshopper, Melanoplus femurrubrum (De Geer), and Tachysphex may also prey on Acrididae. The organ-pipe mud- daubers of the genus Trypoxylon capture spiders. Several nests of T. politum were opened and found stocked with the orb weavers, Neoscona sacra (Walck.) [A. benjamina (Walck.)] and Araneus sp. The great golden digger, Chlorion ichneumoneum, and its relatives prey on longhorn grasshoppers, katydids, and crickets. Mem- bers of the genus Sphex, which are slender black wasps with the basal half of the abdomen orange, nest in the ground and provision their nests with caterpillars. They have been observed capturing bollworms and carrying them intact to their nests. The mud daubers of the genera Sceliphron and Chalybion provision their nests with a wide selection of spiders, black widows, orb weavers, and crab spiders but not generally including wolf spiders. They are important enemies of the green lynx spider, Peucetia viridans. The cicada killer uses a sandy cotton field as a base of operations and often brings its cicada prey to the cotton field from some distance. Wasps of the genus Bicyrtes prey on immature Hemiptera. The horse guard, Bembix Carolina, captures horse flies on the wing. Cerceris wasps stock their nests with beetles and weevils.

THE SPIDERS

All spiders are predaceous and therefore expected to be beneficial. Actually, from the farmer’s point of view, they have various roles. They prey on destructive insects; there is not a single pest of Arkansas cotton that is not attacked by several species of spiders. Many spiders, however, destroy beneficial forms. Since most predators are very active fliers, they are especially apt to be caught by the large webs spun between cotton plants by the orb weavers; but crab spiders, sack spiders, lynx spiders, and jumping spiders capture big-eyed bugs, the insidious flower bug, lady beetles, and others. One green lynx spider was observed to capture four vespid wasps within a few hours’ time. On the other hand, the enormous numbers of spiderlings in the cotton field serve as much-needed food for various predators. One convergent lady beetle fed on 50 eggs of the sack spider, Chiracanthium inclusum (Hentz), in one P r e d a t o r s o f A r k a n s a s Co t t o n F ie l d s 41

Table 2. Seasonal Abundance of Common Spider Species as Represented by Number of Adults Taken in Cotton Fields in Conway County, during 1960 and 1961 June June July July Aug. Aug. Sept. Sept. Oct. Spider species 1-15 15-30 1-15 15-31 1-15 15-31 1-15 15-30 1-15

Frontinella communis (Hentz) 6 12 7 2 Erigone autumnalis Emerton 6 17 7 "4 3 2 1 Dictyna segregata Gertsch & Mulaik 1 1 2 2 3 3 Theridion australe Banks 1 1 3 7 3 2 Theridula opulenta (Walck.) 3 1 5 3 2

M im ognatha fo x i (McCook) 1 2 1 4 1 Tetragnatha laboriosa Hentz 2 1 3 1 4 1 Cyclosa turbinata (Walck.) 2 2 5 7 2 Acanthepeira stellata (Walck.) 1 9 7 1 Neoscona arabesca (Walck.) 5 12 2 6

Mangora gibberosa (Hentz) 5 2 1 Pardosa milvina (Hentz) 9 16 14 25 2 0 8 14 Pardosa saxatilis ( Hentz) 1 5 2 4 3 Pardosa pauxilla Montgomery 1 6 2 1 3 2 Schizocosa avida (Walck.) 2 2 1 4 2 2 3

Lycosa helluo Walck. 5 3 7 12 23 1 15 Oxyopes salticus Hentz 2 8 10 17 26 2 1 2 Meriola decepta Banks 2 2 2 3 20 Chiracanthium inclusum (Hentz) 1 3 6 7 "5 Clubiona abbotii L. Koch 1 1 8 1 2 1 6 10

Misumenoidee aleatorius (Hentz) 1 1 2 Hentzia palmarum (Hentz) 1 7 1 Metaphidippus galathea (Walck.) 1 1 2 11 28 2 4 11 Phidippus variegatus (Lucas) 3 1 1 2

hour. Still another crucial factor is the constant competition between insects and spiders for food. Immature jumping spiders, for example, capture prey very similar to those taken by the big-eyed bugs. The seasonal abundance of some common spider species in cotton fields in Conway County is shown in Table 2. Filistatids— Filistatidae Filistata hibernalis Hentz This species was found only incidentally in the cotton field. It was found more often under undisturbed stones or in crevices of old buildings. The authors took numerous specimens from leaf litter in woods. Feather-legged Spiders— Uloboridae Uloborus americanus Walck. Hyptiotes cavatus (Hentz) Both of these species were found only occasionally in the cotton field. The web of Uloborus americanus resembles that of an orb weaver. Hyptiotes cavatus, the well-known triangle spider, spins a web shaped like a sector of pie. Uloborus americanus has been taken repeatedly while feeding on the coccinellid Scymnus fraternus on the cotton plant. 42 Ar k a n s a s E x pe r im e n t St a t io n , Bul l e t in 690 Dictynids— Dictynidae Dictyna hentzi Kaston Dictyna volucripes Keyserling Dictyna segregata Gertsch and Mulaik The Dictynidae is a large family of small spiders, but only three species were taken in Arkansas cotton fields. The most common species, Dictyna segregata, was found close to the ground. D. hentzi was taken high on the plant. Comb-footed Spiders— Theridiidae Achaearanea globosa (Hentz) Theridion intervallatum Theridula opulenta (Walck.) Emerton Dipoena nigra (Emerton) Theridion neshamini Levi Latrodectus mactans (Fabr.) Theridion pictipes Keyserling Theridion australe Banks Theridion rabuni Chamberlin Theridion differens Emerton and Ivie Theridion frondeum Hentz The family Theridiidae was fairly well represented. The tangled webs of Theridion were commonly found about two-thirds of the way up the cotton plant. These webs captured various species of small flying insects. Theridula opulenta, a tiny, dark, roundish spider, spins a harp-shaped web of parallel strands between the cotton leaves. This sometimes consists of only three or four threads; each thread is characteristically forked where it is attached. This species often feeds on small Diptera. The black widow spider, Latrodectus mactans, spins its web in the lowest branches of the cotton plant. It feeds freely on beetles, as reported by Exline and Hatch (36). It attacked the boll weevil in both the field and the laboratory. Nesticids— Nesticidae Nesticus pallidus Emerton This species is best known as a cave spider but is not uncommon under clods of dirt in the cotton field. It was often taken in pitfall traps. Sheet-web Spiders— Linyphiidae Linyphiella coccinea (Hentz) Bathyphantoides sp. Frontinella communis Tennesseellum formicum (Hentz) (Emerton) Linyphia maculata Emerton Meioneta meridionalis Linyphia marginata Crosby and Bishop C. L. Koch Meioneta micaria (Emerton) Lepthyphantes sabulosa Centromerus sp. (Keyserling) P r e d a t o r s o f A r k a n s a s Co t t o n F ie l d s 43

The family Linyphiidae is a large group, with many species commonly found in the cotton field, mostly on webs across cracks in the ground, between clods of dirt, or near the base of the cotton plant. Frontinella communis is the “bowl and doily” spider of Com- stock (29). In the over-all predator picture, this family is probably of less importance than some other groups. Erigonids— Erigonidae Ceraticelus creolus Eperigone trilobata Chamberlin (Emerton) Gonatium rubens (Blackwall) Grammonota inornata Erigone autumnalis Emerton Emerton Erig one sp., aff. praecursa Grammonota texana (Banks) Chamberlin and Ivie Islandiana sp., aff. flaveola Eperigone maculata (Banks) (Banks) Eperigone tridentata Walckenaera vigilax (Emerton) (Blackwall) Floricomus sp. The species of this family occupy a somewhat similar niche to that of the preceding family. They were often found when trash from under the cotton plant was placed in the Berlese funnel, and were also taken extensively in pitfall and suction traps. Orb Weavers—-Argiopidae Mimognatha foxi (McCook) Metepeira labyrinthea Tetragnatha elongata Walck. (Hentz) Tetragnatha laboriosa Hentz Acacesia hamata (Hentz) Leucauge venusta (Walck.) Verrucosa arenata (Walck.) Allepeira lemniscata (Walck.) Wixia sp. Argiope aurantia Lucas Araneus sp. aff. thaddeus Argiope trifasciata (Forskal) (Hentz) Cyclosa turbinata (Walck.) Araniella displicata (Hentz) Mangora gibberosa (Hentz) Neoscona arabesca (Walck.) Acanthepeira stellata Neoscona sacra (Walck.) (Walck.) Eustala anastera (Walck.) Acanthepeira venusta Micrathena gracilis (Walck.) (Banks) Micrathena sagittata (Walck.) The orb weavers form one of the dominant arachnid families of the cotton field. They are most easily observed at night. The webs are most visible in early morning, when dew has been deposited on them and they have remained undisturbed. The large species mature late in the season, but the immatures feed freely on both beneficial and pest insects. The large net of the mature 44 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690

Figure 8. A star-bellied orb weaver, Acanthepeira stellata (Walck.) star-bellied orb weaver, Acanthepeira stellata (Figure 8), captures many noctuid moths, such as adult bollworms and cotton leafworms. This is also true of Neoscona arabesca, N. sacra [N. benjamina (Walck.)], and the members of the genus Araneus. Tetragnatha laboriosa was found feeding freely on various species of nemocerous Diptera. Pirate Spiders— Mimetidae Mimetus epeiroides Emerton This species was usually taken on the ground in the cotton field. Archer (4) reported that members of this family fed exclusively on other spiders. Funnel-web Weavers— Agelenidae Agelenopsis emertoni Agelenopsis pennsylvanica Chamberlin and Ivie (C. L. Koch) Cicurina arcuata Keyserling The funnel webs of the two species of Agelenopsis were commonly found in cotton fields throughout Arkansas, usually two- thirds of the way up the cotton stalks. Both of these species apparently mature in the fall. Bilsing (17) reported that Agelena sp. will attack a grasshopper much larger than itself. He also mentioned that one speci- men penned up in a tin box captured 40 leafhoppers in a day. P r e d a t o r s o f A r k a n s a s Co t t o n F ie l d s 45

Cicurina arcuata was taken from the ground stratum only. Mature spiders were captured only in the winter (January and February). Hahniids— Hahniidae Neoantistea agilis (Keyserling) This species was taken on a delicate sheet web near the surface of the ground. The webs were most easily seen on mornings with heavy dew. Nursery-web Spiders— Pisauridae Dapanus mirus (Walck.) Dolomedes triton sexpunctatus Hentz Dap anus mirus [Pisaurina mira (Walck.)] is commonly called the poison ivy spider, since it is frequently found with its egg sac on this plant. It is often found three-fourths of the way up a cotton plant with its legs spread out on a leaf, apparently awaiting prey. Records show it to be more abundant north of the Arkansas River than south of it. Members of the genus Dolomedes tend to be semi- aquatic and were found only in low, wet fields. One adult Dolomedes sp. was taken feeding on a half-grown crayfish. Dolomedes sp. was found feeding freely on other spiders, particularly Pardosa lapidi- cina Emerton. W olf Spiders— Lycosidae Pirata alachua Gertsch and Schizocosa avida (Walck.) Wallace Schizocosa crassipes (Walck.) Pirata sedentarius Schizocosa ocreata (Hentz) Montgomery Schizocosa retrorsa (Banks) Pirata suwaneus Gertsch Lycosa annexa Chamberlin Pirata sylvanus Chamberlin and Ivie and Ivie Lycosa antelucana Pirata n. sp. A. Montgomery Pirata n. sp. B. Lycosa carolinensis Walck. Arctosa funerea (Hentz) Lycosa gulosa Walck. Arctosa sublata Lycosa helluo Walck. (Montgomery) Lycosa punctulata Hentz Pardosa milvina (Hentz) Lycosa rabida Walck. Pardosa pauxilla Montgomery Trochosa acompa Pardosa saxatilis (Hentz) (Chamberlin) This is another dominant spider family in the cotton field (Fig- ure 9). Members of this group were seldom seen on the cotton plant in the daytime. Most species are nocturnal ground dwellers; some make permanent holes, but others are vagrants. Immatures of 46 A r k a n s a s E x p e r im e n t S t a t io n , B u l l e t in 690

Figure 9. A pair of wolf spiders, Lycosa carolinensis Walck., mating. Pardosa milvina were found swarming over the cotton plant at night during much of the summer. Clark and Glick (27) found evidence that this species fed on the pink bollworm moth. Lycosa rabida, a large climbing wolf spider, feeds freely on noctuid moths. At about 9 P.M. on a clear August night in almost any Arkansas cotton field not too heavily treated with insecticide, these spiders can be seen halfway up the cotton stalks feeding on bollworm or cabbage looper moths. Several Schizocosa spp. commonly feed on crickets. Lynx Spiders— Oxyopidae Peucetia viridans (Hentz) Oxyoyes salticus Hentz Oxyoyes aglossus Chamberlin Although only two species of Oxyopidae were abundant in cotton, it is an extremely important group. The striped lynx, Oxyoyes salticus, is one of the most common spiders in the cotton field. It is diurnal, but little was learned of the feeding habits. It has been reported to feed on the red-pine sawfly, Neodiprion nanulus nanulus Schedl, in forests. It was taken in cotton feeding on various mirids, including the cotton fleahopper and the tarnished plant bug. There were at least three species of the genus Oxyoyes in cotton, although the only two taken in the mature stage were O. salticus and O. aglossus. The green lynx, Peucetia viridans, is a large green spider common in southern Arkansas. Whitcomb (94) reported that this P r e d a t o r s o f A r k a n s a s Co t t o n F ie l d s 47 species reached maturity in Arkansas during July, but that egg sacs were not found until the middle of September. It spreads itself out on the upper surface of a leaf in the plant terminal and awaits its prey. The dry carcasses of bees, wasps (especially Polistes spp.), bollworm moths, cotton leafworm moths, and cabbage looper moths were found below the spider. At Hope, this spider was observed seizing bollworm and cotton leafworm moths and capturing wasps of the genus Polistes.

Gnaphosicfs— Gnaphosidae Cylphosa sericata (L. Koch) Drassyllus gynosaphes Drassodes sp., aff. Chamberlin auriculoides Barrows Drassyllus mephisto Geodrassus sp., aff. phanus Chamberlin Chamberlin Drassyllus n. sp. Poecilochroa famulus Zelotes duplex Chamberlin (Chamberlin) Zelotes hentzi Barrows Drassyllus creolus Chamberlin Zelotes laccus (Barrows) and Gertsch Zelotes subterraneus Drassyllus fallens Chamberlin (C. L. Koch) This is a large family of spiders, moderate to small in size, that are found in leaf trash and under stones in the ground zone of cotton fields. As reported by Kaston (62), members of the genus Zelotes move quickly and are difficult to take by hand. Most specimens captured in this study were taken from pitfall traps or Berlese funnels. Sack Spiders— Clubionidae Clubiona abbotii L. Koch Castianeira longipalpus Clubiona catawba Gertsch (Hentz) Clubiona saltitans Emerton Micaria vinnula Gertsch Clubiona sp., aff. johnsoni Trachelas tranquillus (Hentz) Gertsch Meriola decepta Banks Chiracanthium inclusum Scotinella fratella (Gertsch) (Hentz) Scotinella pallida Banks Castianeira descripta (Hentz) Phrurotimpus alarms (Hentz) In the cotton field, members of the genera Clubiona and Chira canthium were most often found during the day in silken tubes under bracts or leaves. Chiracanthium inclusum, a moderate-sized, cream-colored species, was the most common of all spiders beneath the bracts of cotton squares and bolls in Arkansas. At times, as high as 10 percent of the fruiting forms had such spiders present under the bracts. Little was learned about feeding habits, other than that they hunt at night and hide during the day. They were observed near Hope feeding on other spiders (orb weavers). 48 A r k a n s a s E x p e r im e n t S t a t io n , B u l l e t in 690

Wiesmann (98) reported that in Egypt a similar species, Chiracanthium isiacum Cb., fed on larvae of Prodenia litura Fabr. Baerg (6) reported Chiracanthium inclusum as possibly poisonous, and he included it among his six poisonous spiders of North Amer- ica. No bites have been recorded in Arkansas. Eggs and young of C. inclusum serve as food for both larvae and adults of lady beetles, particularly Hippodamia convergens. Members of the genera Castianeira, Phrurotimpus, and Meri- ola were taken in ground trash under the plants. M. decepta was particularly numerous in pitfall traps.

Anyphaenids—Anyphaenidae Aysha gracilis (Hentz) Anyphaena maculata (Banks) Anyphaena laticeps Bryant These spiders are very similar in appearance and habits to clubionids. All specimens, with only one exception, were taken from the cotton plant, particularly from the foliage. Aysha gracilis was occasionally taken from under the bracts of fruiting forms.

Crab Spiders— Thomisidae Misumenoides aleatorius Synaema parvulum (Hentz) (Hentz) Xysticus auctificus Keyserling Misumenops asperatus Xysticus funestus Keyserling (Hentz) Xysticus texanus Banks Misumenops celer (Hentz) Philodromus satullus Misumenops oblongus Keyserling (Keyserling) Philodromus vulgaris (Hentz) Coriarachne versicolor Thanatus rubicellus Keyserling Mello Leitao Oxyptila monroensis Tibellus duttoni (Hentz) Keyserling Members of the family Thomisidae were particularly numerous in the cotton plant terminals. This may explain why sweeping caught a disproportionate number of them. However, they were found on all parts of the plants. Members of the genera Xysticus and Misumenops were frequently taken on or under the bracts of cotton bolls and squares. An Xysticus sp. was taken feeding on the boll weevil. X. funestus was taken both in pitfall traps and on the plant itself. A very few Misumenops spp. were taken from the ground zone. M. oblongus was taken feeding on a tachinid fly. Misumenops spp. were taken feeding on the big-eyed bug (Geocoris punctipes), the tarnished plant bug (Lygus lineolaris), the striped P r e d a t o r s o f A r k a n s a s Co t t o n F ie l d s 49 cucumber beetle (Acalymma vittata), syrphid flies, and several other small Diptera. Berland (16) and others have reported certain crab spiders as feeding freely on bees. Lovell (69) reported the family Thomisidae as feeding on a wide range of prey, from butterflies and bumble bees to dragonflies.

Jumping Spiders— Salticidae Synemosyna formica Hentz Phidippus hirsutus Barrows Peckhanda picata (Hentz) Phidippus mccookii Thiodina puerpera (Hentz) (Peckham) Hentzia mitrata (Hentz) Phidippus mystaceus (Hentz) Hentzia palmarum (Hentz) Phidippus purpuratus Metaphidippus galathea Keyserling (Walck.) Phidippus variegatus (Lucas) Metaphidippus insignis Icius vitis (Cockerell) (Banks) Habronattus coronatus Metaphidippus protervus (Hentz) (Walck.) Metacyrba taeniola (Hentz) Eris aurantia (Lucas) Metacyrba undata (De Geer) Phidippus carolinensis Zygoballus bettini Peckham Peckham and Peckham Zygoballus nervosus Phidippus clarus Keyserling (Peckham) Jumping spiders are very numerous in the cotton field and are represented by a large variety of species. These spiders are found on all parts of the cotton plant from the terminal to the base (Figure 10). They appear to be diurnal in habit, most of their hunt- ing being done during the day. Metaphidippus galathea and M. protervus are most common under the bracts of squares, blossoms, and bolls. Hentzia palmarum is also numerous in this location. Phidippus variegatus [P. audax (Hentz)] is especially common, particularly on the plant itself, although it usually matures after harvest. Members of the genera Icius, Thiodina, and Habronattus are found on both cotton foliage and the ground. Many species of this family mature in the late summer and early fall. The prey of each species appears to include a wide range of insects but is limited to species that alight or crawl on the plant. At Altheimer, R. Bell took specimens of Metaphidippus sp. feeding on second instar bollworm larvae. Immature Phidippus spp. were taken feeding on the first three instars of the bollworm. Mature P. variegatus fed in the field on both the largest larvae and the imago of the bollworm. The species was also taken feeding on the boll weevil at Prairie Grove, Hope, and Morrilton. At Fayetteville, 50 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690

Figure 10. Jumping spider attacking bollworm larva. this spider invaded large cages of robber flies and captured many of them. Bilsing (17) reported observing this species feeding on the bald-faced hornet, Vespamaculata [Vespula maculata (Linn.)]. Clark and Glick (27) reported the same species as having fed on pink bollworm moths.

THE PREDACEOUS MITES The number of species of predaceous mites in the cotton field will probably prove to be greater than that of spiders. Three times as many families of predaceous mites may be found in Arkansas cotton than are now known to be present. Identification is extremely difficult. Many species have not yet been described. Al- though collection of mites was begun three years ago, very few identifications have yet been received. Predaceous mites are especially numerous on the soil surface but are also found on foliage, stems, and fruits of cotton plants. In Arkansas cotton, mites have been observed feeding on lepidopterous eggs, small insects, and half-grown spiders. Phytoseiids— Phytoseiidae Phytoseiidae have been taken feeding on plant-feeding mites in cotton fields in Mississippi and Hempstead Counties, but none of the specimens have yet been identified to genus and species. At least under certain circumstances, they may be as important a P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 51 biological control factor of spider mites in Arkansas as is the six- spotted thrips. Erythraeids— Erythraeidae Balaustium n. sp. Erythraeus n. sp. These reddish predaceous mites, with legs well adapted for running, are fairly numerous in Arkansas cotton fields. The larvae are external parasites on insects and spiders. Sometimes, the wolf spiders Lycosa rabida and L. helluo are so badly crippled with numbers of mite larvae, apparently Erythraeidae and Trombidi- idae, that they can no longer run. The adults of both species have been taken feeding on bollworm eggs. They appear to be most numerous under hot, dry conditions. In the field, one individual has been observed to destroy 15 out of 25 eggs in 5 1/2 hours.

Trombidiids—Trombidiidae Although mites of this family are fairly abundant in Arkansas cotton fields, none has yet been identified to species. A dense coat of setae and their bright color give them the appearance of bits of red velvet. Many trombidiid larvae parasitize arthropods; they apparently are capable of transmitting microorganisms from one arthropod to another. Both nymphal and adult stages attack eggs and early larval stages of many insects. According to Severin (80), the grasshopper mite, Eutrombidium trigonum (Hermann), is an important enemy of locusts. Mites taken feeding on bollworm eggs in cotton in 1962 at Morrilton were identified as members of this family. Trombiculids—Trombiculidae This is another family of mites with the appearance of red velvet. According to Baker and Wharton (10), they may be distinguished from the trombidiids by their figure-eight-shaped body. Trombidiids never have quite this shape. Adult trombiculids appear to be tbundant in Arkansas cotton fields, though none has yet been identified to genus and species. Trombiculid larvae parasitize terrestrial vertebrates, including man and domestic animals; the common chiggers belong in this group. As nymphs and adults, trombiculids feed on eggs and early larval instars of small arthropods. 52 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690 PREDATION ON BOLLWORM EGGS Experiments with Bollworm Eggs, 1962 Little detailed information is available about how many eggs or larvae of pest insects will be destroyed by a given population of predators in the field. For this reason, studies were made of the fate of 6,000 bollworm eggs placed in an untreated cotton field near Morrilton during the summer of 1962. Bollworm eggs were chosen for this experiment partly because of the importance of the bollworm and partly because of the convenience of working with lepidopterous eggs. Moths were collected at night in corn, alfalfa, and Dallis-grass (Paspalum dilatatum Poir.) fields and placed in oviposition cages. Eggs were held on ice until used. A camel’s-hair brush was dipped in egg albumen, touched to a bollworm egg, and then brought against a cotton leaf so the egg was left in position. Eggs were attached on the upper sides of the leaves on one cotton plant and on the lower sides on the next; an egg was placed one-third of the distance up from the bottom of the plant, two-thirds up, and in the terminal of each selected plant. The main set of experiments consisted of ten trials. In each trial, 250 eggs were distributed over 1/50-acre of cotton at a rate of approximately 85 eggs per 100 plants. The eggs were examined 24 hours after being placed in the field (Table 3). Daily predator counts were made (Table 4). It was impossible to distinguish with certainty which species of predator had fed on a given egg. The feeding of most sucking insects left the egg shells compressed and wrinkled, sometimes tepee-shaped. The feeding remains of chewing insects were associated with small pieces of intact egg shell. Some lady beetles and other predators with chewing mouth parts were observed carrying eggs away. The number of bollworm eggs per 100 plants dropped from 84.6 to 52.9 in 24 hours, a reduction of 37.5 percent. Considering that almost three days are required for bollworm eggs to hatch, this is an impressive level of biological control. It projects to a drop from 84.6 to only 20.7 eggs per 100 plants in three days. The most abundant insects with sucking mouth parts in this experiment were found to be the insidious flower bug, big-eyed bugs, damsel bugs, assassin bugs, and green lacewing larvae. They destroyed an average of 11.2 eggs per 100 plants during the first 24 hours. This is a reduction of 13.2 percent and represents 35 percent of the total drop in egg population. P s r o t a d e r

Table 3. Number of Bollworm Eggs Destroyed, Compared with Number

of Predators Present, July 7 to August 24, 1962 f o A Date of record or observation s a s n a k r Item July 7 July 13 July 20 July 27 Aug. 3 Aug. 8 Aug. 15 Aug. 17 Aug. 22 Aug. 24

No. of plants 288 309 305 294 303 300 292 305 264 295 No. of eggs placed 250 250 250 250 250 250 250 250 250 250

No. of eggs pierced1 37 30 21 20 13 21 56 38 52 42 C No. of eggs chewed1 34 11 13 6 22 20 13 21 17 17 No. of eggs missing2 66 38 37 38 33 44 35 50 34 58 n o t t o Predators per 1/50-acre plot (3-day average) Sucking predators Green lacewing larvae 0 0 8 1 15.7 8.1 14.0 19.4 31.5 35.2 40.3 F

Big-eyed bug adults 32.6 13.4 37.6 34.3 23.2 26.0 37.0 42.7 21.1 28.5 s d l e i Big-eyed bug nymphs 3.8 9.3 20.3 60.7 43.4 70.0 60.3 67.1 75.7 107.2 Damsel bug adults 3.8 1.0 2.0 36.2 48.4 39.0 21.4 20.3 16.7 10.8 Damsel bug nymphs 0 0 1.0 5.9 9.1 22.0 14.6 21.3 18.5 14.7 Assassin bugs 1.0 1.0 6.1 2.9 5.0 16.0 6.8 9.1 9.7 6.9 Insid. flower bug adult 10.7 5.1 8.1 13.7 11.1 12.0 64.2 60.0 78.3 68.8 Insid. flower bug nymph 1.0 4.1 12.2 17.6 3.0 3.0 9.7 10.2 8.8 10.8 Total 52.9 33.9 95.4 187.0 151.3 202.0 233.4 262.2 264.0 288.0 Chewing predators Ground beetles (Lebia) 1.9 0 1.0 1.0 0 2.0 22.4 32.5 22.9 27.5 Collops spp. 1.9 0 1.0 1.0 1.0 3.0 2.9 3.0 4.4 2.9 Large lady beetle adults 40.3 12.4 31.5 57.8 30.2 49.0 35.8 33.5 48.3 48.1 Large lady beetle larvae 3.8 1.0 16.3 19.6 19.2 26.0 44.8 27.4 14.1 16.7 Scym nus lady beetles 2.9 9.3 9.2 8.8 12.1 19.0 14.6 12.2 14.1 12.8 Predaceous mites 0 0 0 0 0 0 17.5 18.3 20.2 17.7 Total 50.8 22.7 59.0 88.2 62.5 99.0 138.0 126.9 124.0 125.7 3-day av. temp., °F. 87.2 3 78.4 75.1 75.0 85.5 75.4 77.3 82.2 80.5 3-day av. humidity, % 62.3 78.2 69.4 85.8 72.5 68.9 63.2 71.4 77.6

1During 24-hour feeding period. -A fter 24 hours. 3Not recorded. 53 54 Ar k a n s a s E x pe r im e n t St a t io n , Bu l l e t in 690 0.8 3.0 0 0 0.5 7.5 3.0 1.3 0 0.5 1.8 2.0 2.3 0 5.8 2.3 0 0.8 2.5 0 1.5 9/6 29.0 15.5 20.5 24.5 9/3- 19.3 0.7 9.8 4.0 0 0.2 2.2 0.7 2.2 0.2 1.0 0.7 1.8 0.7 2.2 2.0 0.2 0 4.3 9/1 12.0 16.7 30.2 10.5 33.3 21.8 13.8 14.3 8/27-

0 8.2 5.0 5.8 8.7 0 2.8 3.2 0 1.0 0 1.7 2.0 1.2 0.2 4.3 4.2 0.3 0 4.3 4.8 8/25 12.3 11.7 30.0 24.0 12.5 8/20- 0.7 8.3 7.0 5.5 0 9.8 2.0 2.8 0.2 0.7 0 1.0 0.8 3.7 0.5 6.0 0 4.5 0.7 8.0 8.3 13.0 22.7 23.6 17.5 8/18 12.0 8/13- 0.2 9.8 7.2 5.3 3.8 1.8 0 5.5 1.3 0.3 0 1.0 3.0 5.5 9.3 0.8 0.8 9.7 6.0 0 0 9.8 5.8 8/11 8 /6 - 19.5 14.3 12.2 0.5 9.0 2.7 2.2 0 1.0 1.7 0 4.3 2.0 0 8.0 0.3 0.2 1.2 8.2 6.5 4.8 5.0 0.3 0.3 6.5 3.2 8/4 10.8 15.7 12.8 7/30- 1.5 0.7 8.7 8.5 6.0 0 1.0 0.5 4.0 0 9.7 0 0.5 4.8 3.5 9.8 0.2 2.0 5.8 2.8 0.2 0.2 2.7 2.5 7/28 10.3 15.3 7/23- 0.5 0.5 0 5.5 2.2 5.3 1.0 0.2 2.2 2.3 0 0.7 0.2 0.2 1.5 3.3 0.3 4.0 2.2 2.8 2.0 0 0.3 1.3 4.0 11.7 7/21 7/16- Period of observation 0.2 0.5 0.5 8.8 1.8 0 0.3 2.8 0.3 7.5 0.3 0 1.7 0 0.2 1.0 1.0 1.8 0.5 1.8 4.8 0 0.3 6.0 1.0 4.0 7 /9 - 7/14 0 0 0 7.8 0.7 1.0 0 0 0.3 0.3 6.3 0 0.2 0 0.3 1.3 0.3 3.8 0.5 0.8 2.0 0 0.2 6.2 0.7 7 /7 7 /2 - 10.0 0 6.7 0.5 0 0.2 0 0 0 0 0 2.7 0 0 1.3 0 0.3 0.2 0 3.7 0.3 0 3.7 0.3 6.7 0 6/30 15.3 6/25- 0 3.2 0 0 0 0 0 0 0 2.3 0 0 0 3.7 0 0 0.5 6.2 0.2 0.8 2.0 3.2 0 0 1.3 6/23 6/18- 10.3 0 2.2 0 0.2 0 0 0 0 0 3.5 0.2 0 0.2 0 0 0.2 0.8 0 0 4.7 4.2 0 0 0.5 2.8 6/16 12.2 6/11- 0 0 0.2 0 0 0 0 0 0 0.8 0 6 /9 0.5 0 0 0 0 0.2 0.7 0.2 0 0 0.2 0 0.2 0 8.0 6 /4 - le 4. Average Weekly Predator Populations per 100 Plants in a Cotton Field, Summer, 1962 Tab

n y m p h

sp p . w asp s sp p . sp p . sp p . P re d a to rs Big-eyed bugs Nabid adultsNabid nymphs Big-eyed bug nymphs 9-spotted lady beetleSpotted lady beetle Collops balteatus Green lacewingBrown lacewingslarvae L eb ia Collops quadrimaculatus Convergent lady beetleOther lady beetles Other ground beetles Green lacewings Z e lu s Orius insidiosus Lebia analis Lady beetleS c ylarvae m n u s Other predators S in e a P o listes Robber flies Orius insidiosus A n ts P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 55

The most abundant predators with chewing mouth parts were found to be the nine-spotted lady beetle, the spotted lady beetle, the convergent lady beetle, the Scym nus lady beetles, Collops, and ground beetles of the genus Lebia. Predaceous mites, Trombidiidae and possibly Erythraeidae, destroyed a small number of eggs. Shells of eggs eaten by predators averaged 5.9 per 100 plants. In addition, an average of 14.7 eggs per 100 plants disappeared. Chew- ing insects were observed carrying some eggs away. In experiments in 1963, reported in the next section, essentially all missing eggs were removed by chewing predators. Thus it appears that the missing eggs should be credited to chewing predators. If so, they accounted for 20.6 eggs per 100 plants. This is a reduction of 24.3 percent and represents 65 percent of the drop in egg population. The effect of number of eggs on the level of predation was investigated, beginning in the middle of August. When 50 eggs were distributed over 1/50-acre at 18 eggs per 100 plants, the field population of sucking predators destroyed an average of 4.0 eggs per 100 plants, and chewed and missing eggs amounted to 4.9 eggs per 100 plants. Total predation in 24 hours appeared to be 8.9 eggs per 100 plants or 49.4 percent. Increasing the number of eggs to 84.6 per 100 plants gave values of 11.2 eggs per 100 plants destroyed by sucking predators and 20.6 eggs per 100 plants chewed and missing. Total predation in 24 hours was 31.8 eggs per 100 plants or 37.5 percent. Increasing the number of eggs to 330 per 100 plants gave values of 61 eggs per 100 plants destroyed by sucking predators and 128 eggs per 100 plants chewed and missing. Total predation in 24 hours was 189 eggs per 100 plants or 57.3 percent. The number of eggs destroyed by predators increased as the number of eggs increased. However, the percentage destroyed did not change consistently as the number of eggs increased and probably is well within the range of normal variation. Significantly more eggs (at the 1 percent level) were consumed in the lower part of the plant than in the terminal (Table 5).

Table 5. Effect of Location of Bollworm Eggs on Predator Feeding, Summer, 1962 (Average Number of Eggs Consumed in Nine Experiments, Each Consisting of 1/50-Acre with 250 Eggs)

Location on plant Observation T erm inal Middle Bottom

Eggs pierced 9.1 9.7 13.9** Eggs chewed 4.3 5.8 7.0 Eggs pierced and chewed 13.4 15.5 20.9** Eggs missing 11.3 13.4 18.1** Normal eggs 58.3 55.1 44.0**

**Significantly different at the 1% level. 56 Ar k a n s a s E x p e r im e n t S t a t io n, B u l l e t in 690

When pierced and chewed eggs were checked individually, signifi cantly more pierced eggs were found low in the plant than in the terminal, but this was not true of the chewed eggs. This should be of particular interest to farmers and cotton scouts, since it could explain why terminal egg counts do not always represent the situ ation in the field.

Experiments with Bollworm Eggs, 1963 In the 1962 experiments, when bollworm eggs were placed on the leaves of cotton plants in the field and examined after 24 hours, it was found that almost half of the eggs disappeared without a trace. Other workers have reported a similar disappearance of eggs that were not obviously destroyed by predators. Fletcher and Thomas (37) reported 43.7 percent of eggs miss ing in 1938 and 11.2 percent in 1939 in their study of the fate of naturally deposited bollworm eggs on cotton. Phillips and Barber (76), while working on the fate of bollworm eggs on the corn plant, had an average of about 40 percent missing eggs that were not attributed to predators. Harrison (46), in 1960, had an average of about 25 percent of eggs missing while working with the fate of bollworm eggs on corn silks. In experiments dealing with the fate of tobacco hornwormProtoparce eggs, sexta (Johannson), on to bacco, Lawson (65) reported 47.3 percent of the eggs to be missing. Many explanations have been given as to the possible fate of part or all of these missing eggs. Since it was fe lt that more con crete explanations were needed, tests were conducted during the 1963 growing season primarily to help explain the fate of these apparently missing eggs. The bollworm egg predation observations were conducted in a one-acre field in the Arkansas River bottoms near Morrilton. This field, as well as surrounding crops and pasture, was free from insecticides during the entire growing season. Crops bordering the test field included cotton and soybeans. The experiments were conducted once or twice a week, start ing July 11 and ending September 3. During this period, a total of 14 standardized tests were conducted, each of which started at 6 A.M. and ended at 6 P.M. to give 12 continuous daylight hours of observation. In each test, 150 bollworm eggs were placed on the upper sides of six cotton leaves, so that each leaf received 25 eggs. The leaves were usually located on six different plants. The eggs were at tached to the cotton leaves by the use of fresh egg white and a P redators of A r k a n s a s Cotto n F ie ld s 57

Table 6. Observations of Predator Feeding on Bollworm Eggs in 1963

P re d a to r Total eggs E g g shell E g g s h e ll observed feeding a tta c k e d remains absent remains present

A n ts 119 119 0 Lady beetle larvae 231 175 56 Coleomegilla m aculata 51 51 0 Hippodamia convergens 25 20 5 J umping spiders 38 20 18 Grasshopper nym ph 1 1 0

Predaceous mites 31 3 28 Green lacewing larvae 18 3 15 Orius insidiosus 16 0 16 Ceratocapsus sp . 1 0 1 camel’s-hair brush. An observer was stationed about three feet from the plants. Each feeding observation was recorded separately, and the leaves were examined afterwards fo r the remains of egg shells. The predator involved was recorded as to species when possible. A total of 531 predator feeding observations were made. Five orders of insects, one family of spiders, and one family of mites were represented. Table 6 shows the results of the observation experiments. One hundred nineteen eggs were removed by ants, which were deter mined to Paratrechina be sp. andIr idoomyrmex pruinosus. Upon discovering an egg, the ant chewed and pried around the base of the egg with its mandibles, and when it succeeded in dislodging it, the ant grasped the egg in its mandibles and carried it to its burrow. After three or four I.trips, pruinosus was usually aided by other members of the colony, and a cotton leaf would soon be entirely cleared of bollworm eggs. The remainder of the chewing predators, those that consumed the eggsin s itu on the cotton leaves, destroyed a total of 346 boll worm eggs. Of these, coccinellids consumed 307 eggs, including those eaten by lady beetleColeomegilla larvae, maculata adults, andHippodamia convergens adults. The largest number of eggs consumed was by the lady beetle larvae, which left shell remains in only 56 out of 231 feeding observations.H. convergens adults left identifiable shell remains in five instances out of 25 eggs eaten, whereasColeomegilla maculata consumed 51 eggs and le ft no re mains. Jumping spiders are also included in the mandibulate preda tors, and they destroyed a total of 38 bollworm eggs. While feeding, the jumping spiders pulled the eggs loose in 20 cases. A fte r feeding, they dropped the raggedly chewed shells, and these either fell to the ground or were blown o ff the leaves by the wind. 58 A r k a n s a s E x p e r im e n t S t a t io n, B u l l e t in 690

Another chewing predator, a longhorn grasshopper nymph, fed on only one egg and, in this case, le ft no shell remains. Piercing and sucking predators fed on a total of 66 bollworm eggs. Of these, 31 were destroyed by predaceous mites. Specimens of two of these mites were identified as new species of the two genera,E rythraeus andB alaustium of the family Erythraeidae. Only 3 shells were dislodged during the 31 feeding observations. Green lacewing larvae dislodged 3 shells out of 18 eggs de stroyed. In all 16 cases, the insidious flower bug left the egg shell in place after feeding. A plant bugCeratocapsus nymph, sp., ob served feeding on one bollworm egg, le ft the shell in place. It is evident that predation on the bollworm eggs was not that of one or two species, but rather of a variety of predators. Some species are more abundant at one time, and other species at other times. The results of these studies strongly suggest that most of the missing eggs in the M orrilton experiments o f 1962, and possibly some of the eggs reported as missing by other workers, were not due to mechanical or physical factors but to biotic factors. According to these results, the disappearance of the eggs was largely due to the feeding activity of predators with chewing mouth parts, such as the coccinellids and the ants. In very few cases did the piercing and sucking predators dislodge the egg shell. In these direct observations it was found that, of the total eggs attacked, 74 percent of the shells were completely missing after feeding. However, in the 1962 experiments, where eggs were examined after a 24-hour feeding period, it was found that the shells were missing only about 46 percent of the time. Others doing similar work have found even lower percentages of missing eggs that they could not attribute to predator feeding. The ques tion that then arises is the reason fo r the seemingly high propor tion of missing eggs in the 1963 observations. As was mentioned, the piercing and sucking predators seldom dislodge egg shells after feeding, and in this experiment it can be seen that these predators were less important than chewing predators in regards to feeding activity, especially the insidious flower bug. A large part of the missing shell discrepancy may be due to this lower than normal percentage of insidious flower bug feeding. The field population of the insidious flower bug in 1962, as compared to that of 1963, was about the same (Figure 11). Three possible explanations have been given as to why the insidious flower bug appeared less im portant in the observations of 1963 : (1) it is possible that it tends to feed more at night, and all of the results were based on daytime P redators of A r k a n s a s Cotton F ields 59 feeding; (2) it was observed that the insidious flower bug fed most actively on cloudy days and on days when the hum idity was rela tively high; and (3) the adults of this species were easily frightened away by any sudden movements made by the observer.

Figure 11. Weekly average number of adult insidious flower bugs per 100 cotton plants near Morrilton, 1962 and 1963.

HIBERNATION

Predators are such a varied group that it is not surprising to find them overwintering in every stage. In the family Reduvi- idae, for example,Sinea spinipes hibernates as anZelus adult; exsanguis overwinters as a nym ph; and the wheel bug, as an egg. Within the genusChrysopa of the green lacewings,C. plorabunda overwinters as an adult;C. oculata overwinters as an egg; and still other species overwinter as larvae in pupal cocoons. Among spiders, the black and yellow gardenArgiope spiders, aurantia, overwinter as spiderlings that have hatched but are still w ithin the egg sac; the green lynx spider overwinters in the second and third instars;Lycosa carolinensis, a w olf spider, tends to overwinter half grown; andL. punctulata, another common wolf spider, overwin ters as a mated adult female. Hibernation quarters vary from one species to another. Even though the overwintering habits of seven species in a genus are 60 A r k a n s a s E x p e r im e n t S t a t io n, B u ll e t in 690 well known, the eighth frequently cannot be found during the win ter. A fter leaving cotton, some species pass one more generation on weeds or fa ll legumes before entering actual wintering quarters. Other species, such as the spotted lady beetle, may go directly into hibernation from cotton. Apparently the most important characteristic of any location fo r hibernation is that the area be well drained. Generally, only aquatic or semi-aquatic insects overwinter where water stands. The number of insects hibernating in a rice levee is high because it is the best drained point nearby. It is also axiomatic that there must be some kind of protection from the wind. I f the location is too exposed, the changes in the bioclimate w ill be much too rapid for the insects to adjust to them. Surprising as it may seem, old buildings, abandoned sheds, or even outhouses make excellent overwintering quarters for some predators, especially if they can enter the space between double walls. The various speciesPolistes, of Vespula queens, and many species of spiders take advantage of this kind of protection. Hollow logs or stumps make good hibernation quarters. Dan ger from other predators is high, however. The most active period of some species of spiders is during January and February; they even construct their egg sacs at this time. InVespula spite of this, queens, ground beetles, reduviids, and other insects overwinter there. Dead,standing trees w ith semi-loose bark make good over w intering quarters. The wood must not have started to rot, and the bark must not be too loose. Several species of Hemiptera overwin ter in such a location, including thePselliopus reduviids, barberi andMelanolestes picipes. Jumping spiders overwinter in these quarters as adults in sexual diapause, in thick, white, silken tubes. Several ground beetles and even somePolistes wasps, spp. including andVespula spp., may be found there in the winter. Leaf trash appears to make good hibernation quarters for more species than does any other situation (Table 7). When leaf trash is placed in a Berlese funnel, a surprising number of insects, spiders, and mites emerge. Leaf trash is the normal habitat of some predators and serves as hibernation quarters for others that will not be found there after the first warm days of spring. Ground beetles, especiallyAnisodactylus andStenolophus; the big-eyedGeocoris bug, uliginosus; the nabids,Nobis alternatus, N. ferus, N. roseipennis, N. sordidus, andN. deceptive; the stilt bug,Jalysus spinosus; and the reduviids,Sinea spinipes, Zelus P r e d a t o r s o f A r k a n s a s C o t t o n F i e l d s 61

Table 7. Predator Species Collected from Various Kinds of Trash1

O ak Oak leaves S tra w - leaves, b e rry D ry weeds a nO d n c a n aO l n bayouI n lo w On fie ld grass Species grass b a n k b a n k woods2 h ill tra s h tra s h

Total specimens collected

Nabis alternatus 0 1 1 0 0 0 0 Nabis ferus 0 1 0 0 0 0 0 Nabis roseipennis 1 2 1 0 1 0 0 Nabis sordidus 3 7 3 0 0 0 0 Nabis deceptivus 0 1 2 1 0 2 1 Geocoris uliginosus 1 0 0 0 0 1 0 Sinea spinipes 0 4 0 0 0 0 0 Fitchia aptera 0 1 0 0 0 0 0 Zelus exsanguis 0 13 23 0 0 0 0 Jalysus spinosus 0 0 0 0 1 0 0 M eta pterus fra te rn u .... s 0 0 0 0 1 0 0

adapted from J. Isaza-Restrepo (53). -Site had poor drainage. 3Nymphs were present. socius, Z. exsanguis, andZ. cervicalis, are only a few of the insects found in leaf trash. Sack spiders, jumping spiders, w olf spiders, and funnel-web weavers may hibernate there. The spotted lady beetle appears to prefer dead leaves that are caught between the surface roots of large trees such as pecan and sycamore. The vari ous speciesZelus of overwinter in the leaf trash as half-grown nymphs; in early spring, they climb the nearest bushes and mature. Z. exsanguis becomes sexually mature in April in southern Ar kansas. Many predators overwinter under stones at the edges of fields. In the absence of stones, they overwinter under small logs, boards, or piles of cow dung. Ants, ground beetles, nabids, and several reduviids are typical of this group. The convergent lady beetle can often be found by the hundreds under stones or boards. Spiders of many kinds, particularly w olf spiders, funnel-web weavers, and jumping spiders, also overwinter there. Many predators overwinter in the soil itself, as long as it is well drained. Diapausing adults and last instar nymphs of the reduviidSirthenea carinata are often found in the top four inches of the soil. Both larvae and adult ground beetles overwinter here. Several species of ants apparently simply close up their entrances. Grass clumps are excellent overwintering quarters (Table 8). In Arkansas, broom sedge,Andropogon virginicus Linn., makes especially good hibernation quarters, but other grasses such as crabgrassD ig ( ita ria spp.), wire grass, and weeping lovegrass (Eragrostis curvula) are also satisfactory. The insidious flower bug, the big-eyed bug, Nabis the nabids deceptivus andN. capsi- 62 Table 8. Predator Species Found Throughout the W inter and Their Location1

In dry vegetation In green vegetation

U n d e r B ro o m D r y G reen S tra w M u l Species T ra s h C lum ps stones sedge grass A lfa lf a O ats W h e a t grass V e tc h H e n b itb e rrie s le in

Nabis alternatus X X X X X X X X X X X Nabis ferus X — — __ X X X X X X X — __ Nabis roseipennis X — __ X _ X X ______Nabis sordidus X _ Nabis deceptivus X X __ X X _ _ _ Nabis capsiformis — X — — — X X — — — — — — Geocoris punctipes _ X X X X X X Geocoris uliginosus X _ Orius insidiosus — X _ _ X _ X _ X _ X Sinea spinipes __

X _ _ _ A Fitchia aptera X _ _ _ _ X s a s n a k r Zelus exsanguis X _ _ _ _ _ X _ _ _ Metapterus fraternus X _ _ _ _ X X _ _ _ _ X Jalysus spinosus X X _ _ Jalysus wickhami — — — — — — — — — — — X

1Adapted from J. Isaza-Restrepo (53). E ment n e im r e p x

Table 9. Predator Species Collected From A lfalfa Field in Late Fall of 1957, with Temperature Readings1

Date of collection Temperature ------— ------— ------and species O ct. 21 N o v. 5 N o v . 8 N o v. 12 N o v . 18 N o v . 23 N o v . 26 Dec. 7 Dec. 10 Dec. 13 Dec. 14 Dec. 17 Dec. 29 S Temperature, °C. 16 9 10 9.5 5 8 19.5 8 7 13 7.5 15 18 n io t a t Number of specimens collectedsweeps in 200

Nabis alternatus 18 6 4 7 0 0 6 0 0 0 11 6 0 Nabis ferus 7 1 2 1 0 0 0 0 0 0 11 0 0 B , Nabis roseipennis 192 22 12 72 0 0 42 0 0 0 0 22 0 Nabis deceptivus 0 0 0 12 0 0 42 0 0 0 0 0 0 in t e l l u Nabis capsiformis 3 0 22 0 0 0 1 0 0 0 0 0 0 Geocoris punctipes 0 0 0 0 0 0 8 0 0 0 5 1 0 Geocoris, uliginosus 0 0 0 0 0 0 0 0 0 0 1 0 0 Orius insidiosus 0 0 0 0 0 0 11 0 0 0 0 0 0 Metapterus fraternus 0 0 0 0 0 0 1 0 0 0 0 0 0 690

1 Adapted from J. Isaza-Restrepo (53). 2Nymphs were present. P redators of Ar k a n s a s Cotton F ield s 63

Table 10. Predator Species Collected from Oat Field in W inter of 1957-58, with Temperature Readings1 C o lle ction date Temperature S w eepings N a b is a lte rn a tu s Nabis ferus N a b is roseipennis N a b is dece ptivus N a b is capsiformis G eocoris p u n c tip e s J a lysu s spinosus

°C . N o . Number of specimens collected

Nov. 18, 1957 5 200 0 2 0 0 0 0 0 Nov. 23 10 200 6 5 42 0 0 0 0 Nov. 26 15.5 200 16 15 3 0 2 14 0

Dec. 7 6.5 200 0 0 0 0 0 0 0 Dec. 10 7 200 1 0 0 0 0 0 0 Dec. 13 10 200 8 7 1 0 0 1 0 Dec. 14 14.5 400 11 16 1 8- 0 242 0 Dec. 17 18 300 4 9 0 0 0 0 0 Dec. 23 13 200 1 2 0 1 0 0 0 Dec. 29 7.5 200 0 0 0 0 0 0 0

Jan. 1, 1958 — 1 200 2 0 0 0 0 0 0 Jan. 4 8 200 4 6 2 1 2 3 0 Jan. 6 8 300 3 4 1 0 0 2 0 Jan. 7 — 1 200 0 0 0 0 0 0 0

J a n . 11 15 400 15 10 2 3 2 2 0 Jan. 15 5 200 2 0 0 0 0 0 0 Jan. 17 9 300 4 4 1 0 0 0 0 Jan. 25 12 200 0 6 1 0 0 0 0 Jan. 30 5.5 200 3 1 0 0 0 0 0

Feb. 4 7 200 0 0 0 0 0 0 0 Feb. 5 15 300 10 4 2 0 2 0 0 Feb. 21 14 200 5 0 0 0 0 0 0 Feb. 22 17 700 6 7 1 1 0 0 0 Feb. 23 20 300 3 2 2 0 0 2 0 Feb. 24 19.5 500 10 3 0 0 1 1 1 Feb. 25 20 500 8 9 0 0 0 1 0

M ar. 1 9 300 3 1 0 0 0 0 0 M a r. 2 8 300 2 2 1 0 0 0 0

1 Adapted from J. Isaza-Restrepo (53). 2Nymphs were present. form is, adultLebia spp., and the adult ladyCycloneda beetles ( munda, Olla abdominalis, andScymnus spp.) hibernate in such clumps. Crowns of perennial weeds, such( Verbascumas mullein spp.) and several composites, at times serve as wintering quarters for several predaceous bugs. Some predators such as nabidsNabis alternatus, ( N. ferus, N. roseipennis, N. deceptivus, andN. capsiformis), both big-eyed bugs (Geocoris punctipes andG. u lig in o s, u and s ) O rius spp. w ill go through the winter on green crops like alfalfa and winter grains (Tables 9 and 10). Isaza-Restrepo (53) showed that on warm days, these predators are active (Figure 12) ; and that on cold days, they apparently hide in ground trash in the field itself. As demonstrated by Adarve-R. (1), they are in sexual diapause, and 64 A r k a n s a s E x p e r im e n t S t a t io n, B u l l e t in 690

Figure 12. ComparisonNabis of ferus population in small grain at Fayette ville with the air temperature in degrees Centigrade. the ovaries do not begin to swell until March (Figure 13). Nabids are active at much cooler temperatures than are the big-eyed bugs (Table 10) and the insidious flower bug; therefore, the nabids are more easily collected all winter. Certain predators overwinter in the egg stage. Some eggs are exposed on a branch, as in the case of wheel bug eggs; others are protected. Neither the overwintering stage nor the hibernation quarters of some species are known. Further investigation of hibernation is needed. Predators of A r k a n s a s Cotton F ields 65

Figure 13. A, OvariesNabis of alternatus female in diapause; B, Ovaries of sexually activeNabus ferus fem a le . Adapted from R. Adarve-R. (1).

SOURCE OF PREDATORS

Most predators and parasites must enter the cotton field anew each year, since only a very few overwinter in the field itself. As a result, the nature of the surrounding fields determines, to a con siderable extent, what species of predators inhabit a field of grow ing cotton. A cotton field bordered by pecan orchards and one surrounded by wheat fields are likely to have quite distinct predator populations. Only some of the predators from surrounding fields enter and remain in the cotton field. Not all species of lady beetles pres ent in the pecan orchard appear in theCycloneda cotton field. munda is numerous in small grains and early legumes but almost never becomes the dominant lady beetle in the cotton field. Whit- 66 A rkansas E x p e r im e n t S t a t io n, B u l l e t in 690 comb,et al. (96) showed that, although a pasture bordered a cotton field, only 32 percent of the spiders of the ground stratum of the cotton field were common to both fields. There are a few arthropods that overwinter in the cotton field; no matter how the field is disturbed, they usually manage to maintain themselves. Ants, ground beetles, and wolf spiders have been taken every week of the year in cotton fields. Old buildings are an important source of predators in some cases. This is especially true with paper waspsPolistes, of the genus which overwinter as adults between the walls and emerge to start new colonies in the spring. Several species of spiders also over winter in old houses. Actually, very few predators move directly from overwinter ing quarters to the cotton. Most emerge in late March or early A pril and pass one or two generations on early crops or weeds, and then a portion of the resulting population moves into the cotton field. Early in the season, crimson clover supports large populations of predators. Pea aphids,Macrosiphum pisi (Harris), as well as lepidopterous eggs and larvae of many kinds, serve as an abundant food supply. These predators, however, do not move directly to the cotton field, since crimson clover begins to go to seed in early May before most cotton is up. In those few cotton areas where crimson clover is found, the predators move into com, white clover, vetch, or small grain and then later into cotton. Invetch, the pea aphid again serves as an excellent food sup ply. Syrphids, green lacewings, lady beetles, big-eyed bugs, nabids, and the insidious flower bug multiply greatly in this crop. Unfor tunately, the number of acres of vetch grown in Arkansas is de creasing. A lfalfa is one of the best predator sources in Arkansas. Web- worms Loxostege [ sim ilalis (Guenee) L. and commixtalis (Walk e r)], the green cloverwormPlathypena [ scabra (F abr.)], the alfalfa caterpillarColias ( eurytheme Boisduval), several species of Lycaenidae, the bollworm, and the pea aphid serve as food for a varied group of predators. No other crop normally holds a high predator population over such an extended period. Several species of predators begin to increase even before the last frost in the spring, and counts do not drop completely until after frost. Each time the alfalfa is cut, a mass migration occurs into neighboring crops (Figure 14). This migration may be delayed a few hours in some cases, as injured and exposed prey is consumed. By the Predators of A r k a n s a s Cotton F ield s 67

JUNE Figure 14. Comparison of populations of the convergent lady beetle and the spotted lady beetle in alfalfa and in an adjacent cotton field near M orrilton, 1961. second day, the predator population of a neighboring field usually will have increased. White clover, when it is growing luxuriantly and is not mixed with too much grass, is a fa irly productive source of predators and w ill continue to supply them longer than w ill the early-season legumes. Wheat, oat, and barley fields are good sources of predators. As shown in the previous section, predaceous bugs such as the nabids are active in the field even in the dead of winter when temperatures are high enough.Nabis, In the reproduction genus begins in March, and reproduction of other predators begins soon after that. Several species of aphids and thrips serve as food. Big- eyed bugs, the insidious flower bug, green lacewings, and syrphids are particularly numerous.Cycloneda munda andHippodam ia convergent are usually the dominant lady beetles. About ten days before the grain is ready to cut, the predators begin moving out of the grain. By the time it is cut, only thrips and mites are still numerous in the grain field. Figures 15 and 16 show that as the predator population drops in small grain, it rises in the cotton. 68 A r kansas E x p e r im e n t St a t io n, B u l l e t in 690

Figure 15. Comparison of the convergent lady beetle populations in small grain field A and in an adjacent cotton field near M orrilton, 1961.

Figure 16. Comparison of the convergent lady beetle populations in small grain field B and in an adjacent cotton field near M orrilton, 1961. P redators of A r k a n s a s Cotton F ield s 69

Rice appears to be a poor source of predators. Although nu merous, the spiders found in rice are usually different species from those found in cotton. Corn may be an excellent source of predators. The insidious flower bug reproduces in corn silks faster than in any other crop. Big-eyed bugs become very abundant. A ll common cotton field coccinellids are numerousColeomegilla in corn. maculata tends to be the dominant lady beetle in cotton fields adjoining corn or sor ghum fields.Lebia analis is abundant in corn. The corn leaf aphid [Rhopalosiphum maidis (Fitch)], the bollworm, and the flower thrips are often numerous and serve as prey. Unfortunately corn may become infested with attractive prey and draw the predators from cotton (Figures 17 and 18). The tassel may suddenly extrude, exposing thousands of corn leaf aphids, or the bollworm moth may lay large numbers of eggs on the silks. This may happen when predators are most needed in the cotton. Young, succulent Johnson grass and Sudangrass grown for hay are another predator source. Older Johnson grass, infested

Figure 17. Comparison of the spotted lady beetle populations in corn and in an adjacent cotton field near M orrilton, July, 1961. 70 A r k a n s a sE x p e r im e n t S t a t io n, B u l l e t in 690

Figure 18. Comparison Sof cym the n u slady beetle populations in corn and in an adjacent cotton field near M orrilton, June, 1963. w ith aphids and growing as a weed, may at times supply cotton with large numbers of predators, especially the larger lady beetles and green lacewings. Sorghum, with its heavy populations of aphids and lepidopterous larvae, may be another good source, particularly in late August when other sources are scarce. Sericea lespedeza is a good source of crab spiders, the striped lynx spider, jumping spiders, the insidious flower bug, and predaceous stink bugs. Soybeans planted before May 10 may be a good source of preda tors. Predators of various species feed on lepidopterous eggs and larvae, on leafhoppers, and on Lebia other analis insects. was al most unknown in cotton until soybeans were cultivated in Arkansas on a large scale. On the other hand, late-planted soybeans are usually a poor source of predators; few predaceous insects migrate from such soybeans until late in the season. Bermudagrass pastures are low both in variety and in numbers of predators. Forests are not very promising as predator sources for the cotton field. Although tremendous numbers of predators are present in the forest, they are usually different species from those found in cotton. An exception is the wheel bug. P redators of A r k a n s a s Cotton F ields 71

There is a very long list of weeds that are predator sources, especially fo r certain species. Early-season composites were found to support high populationsThrips abdominalis of (Crawford). The insidious flower bug feedsT. abdominalis freely on and appears in the flower heads very early. In the springs of 1960, 1961, and 1962, dock,Rumex sp., was heavily infested with aphids, and large numbers of syrphids and lady beetles reproduced on it. Careless weed,A m aranthus spp., is often a good source of lady beetles.Coreopsis spp. in bloom have large populations of syrphids, the insidious flower bug, and green lacewings. Flower ing smartweeds,Polygonum spp., provide numbers of lacewings, the insidious flower bug, syrphids, crab spiders, and jumping spiders. Fleabanes,E rig e ro spp., n are populated w ith big-eyed bugs, crab spiders, the striped lynx spider, and jumping spiders. A thorough study is needed to establish which predators are found on the various species of weeds and under what conditions the predators leave the weeds.

NATU R AL ENEMIES OF PREDATORS Other Predators The most spectacular foes of predaceous insects, spiders, and mites are other predators. Many predators are general feeders; it is not surprising that they destroy a few beneficial insects. Others, however, specialize in feeding on certain predaceous arthro pods. Only a few cases involving major predators of the cotton field can be mentioned in this discussion. Van den Bosch,et al. (90) pointed out that, in California, a big-eyed bug is a seriousO enemy rius spp. of In Arkansas, the big- eyed bugsGeocoris punctipes andG. uliginosus attackOrius insidiosus andO. tris tic o lo consistently. r I f plant bugs are numerous, Geocoris spp. appear to attack the plant bugs first. Nymphal big- eyed bugs are preyed on by all species of nabids, and occasionally an adult big-eyed bug is attacked by a nymphal assassin bug. Nab ids are the prey of a wide variety of predators of which the assassin bugs of the generaSinea and Zelus are especially numerous. Robber flies and dragonflies have been captured while feeding on nabids. Various species of true bugs are occasionally taken in the orb webs of several genera of spiders of the family Argiopidae. Lady beetles, especially the convergent and the spotted lady beetles, are destroyed by a host of different predators. Possibly the two most important predators are the Sinea assassin bugs spinipes andS. diadema. Other assassin bugs, especiallyZelus exsanguis, Z. cervicalis, andZ. socius, also attack lady beetles. The 72 A r k a n s a s E x p e r im e n t S t a t io n, B u l l e t in 690 praying mantis,Stagmomantis Carolina, is commonly observed feeding on them. The authors haveCollops observed spp. being attacked by much the same predators as attack lady beetles. Both Collops spp. and lady beetles are attacked by many spiders, both web-spinning and vagabond types. The most im portant enemies of robber flies are other robber flies (Figure 19) ; the larger species feed freely on the smaller species of robber flies of the same or other genera. It is not uncom mon to see a robber fly feeding on another of the same species. Robber flies are captured by dragonflies and by the praying mantis, StagmomantisC a ro lin aRobber . flies are taken in the webs of Neoscona spp. andAraneus spp. Syrphid flies are attacked in both the adult and the larval stages by many predators. Jumping spiders have been observed feeding on the larvae. The adults are captured by robber flies and dragonflies. Syrphid flies have often been ob served in the webs of the big-jawed spidersTetra- of the genus gnatha. The ostm important enemies of wasps o f the families Sphecidae and Vespidae apparently are robber flies. Probably the most com mon robber fly feedingPolistes on annularis in the Arkansas cotton field isPromachus hinei. Another robberProctacanthus fly, mil- b e rtii, kills just as many of this species of wasp in the more southern counties of the state. Many different genera and species of robber flies feed on wasps in general, even occasionally including a pompilid wasp. The large robber fly that resembles a bumble bee, Mallophora orcina, has been taken while attacking a small species ofPepsis of the fam ily Pompilidae. The green lynx spider attacks many wasps, as well as Lepidoptera.P olistes spp. are frequently captured by these spiders while the wasps search the cotton termi nals for lepidopterous larvae. The cotton terminals are a favorite hiding place for female green lynx spiders. As many as six dried, emptyPolistes carcasses have been taken from a cotton leaf just below a female green lynx spider. Spiders themselves are attacked by many insect predators. The yellow-legged mud-dauber,Sceliphron caementarium, attacks a wide variety of spiders, including orb weavers of several species, numerous crab spiders, black widow spiders, and jum ping spiders, but very few wolf spiders. In Arkansas cotton fields, pompilids have been observed attacking mostly wolf spiders and funnel-web weavers. Parasites Less is known about the parasites of predators than about the predaceous arthropod enemies of the predators. Almost all species are parasitized by a hymenopterous or dipterous parasite, and P redators of A r k a n s a s Cotton F ie ld s 73

Figure 19.Diogmites symmachus Loew feeding on another species of robber fly.

many are parasitized by both orders; eggs, larvae, or adults may be parasitized. The eggs of the wheel bug are often parasitized by an unidentified hymenopterous parasite. Syrphid larvae are attacked by several hymenopterous parasites. Nabids are com monly attacked by the tachinid,Leucostoma simplex Fallen (Figure 20). Adult lady beetles are frequently parasitized by a braconid, apparentlyPerilitus coccinellae (Schrank). Spiders are also heavily parasitized. The members of one fam ily of Diptera, the Acroceridae, are exclusively parasites of spiders. Ogcodes dispar (Macquart) is a common parasite of the w olf spi ders,P ira ta spp., in Arkansas. Many spiders are parasitized by several families of Hymenoptera. AAcoloides scelionid, n. sp., was reared in July, 1962, from eggsLycosd of helluo. 74 A r k a n s a s E x p e r i m e n t St a t i o n , B u l l e t i n 690

Figure 20. Parasitized femaleN a b is sp. A d apted from R. Adarve-R. (1). Predators of A r k a n s a s Cotton F ields 75

PREDATORS AND INSECTICIDES

Insecticides may kill predators. However, careful timing of insecticide application can help prevent excessive destruction of predators. Infestations of pest insects vary greatly from year to year, from field to field, and from week to week w ithin the same field. I f fields are carefully scouted weekly, insecticide need be applied only when pest insects are present in destructive numbers. Applications for boll weevil need not begin before late July or early August, except in the case of heavy infestations. In such a program, predators may be of great value in control of bollworms, mites, and aphids. In the summer of 1963, when the boll weevil infestation was especially light, practically no insecticide was applied in Arkansas until after predator populations had dropped excessively from other causes. In this case, the normal situation was reversed. The preda tor population dropped firs t in the source fields and then in the cotton fields, all of this taking place before any insecticide was applied. A bollworm outbreak thus resulted from a natural situa tion and was not insecticide-induced. Predator populations in cotton fields may recover rapidly after insecticide application is stopped, provided there is a high level of predator population in surrounding crops. At Atkins in 1961, a ten-acre cotton field was treated w ith 0.4 lb. of endrin three times. Following these applications, the predator population was as high as ever. A large number of predators on Johnson grass in a nearby soybean field served as a source of predators, and a number of aphids in the cotton field itself gave the predators cause to remain, once they had arrived. It can be stated categorically that the appli cation of insecticide to a field that is a source of predators is even more serious than treatment of the cotton field itself. It is known that certain crops are valuable as sources of preda tors, but selection of crops for maximum financial yield to the farmer and maximum predator yield lies in the future. This ap proach w ill require much more knowledge than we have at present, and its full exploration must await future years. Use of irrigation on nearby fields for greatest crop yield will indirectly benefit the farmer by maintaining a more continuous supply of predators. Proper use of fertilizer to maintain maximum growth and yield also appears to increase predators in many cases. Choice o f insecticides that would k ill destructive insects and not beneficial ones has limited potential for boll weevil or bollworm control. The extremely varied nature of predators reduces the like lihood of finding such a material. A material which would spare 76 A r k a n s a s E x p e r im e n t S t a t io n, B u lle t in 690 only the insidious flow er bug would not solve the problem. It would have to be a material that would not kill ants, lady beetles, the insidious flower bug, nabids, green lacewing flies, and mites, but would kill the boll weevil and the bollworm. Furthermore, the material would have to be one that could be used for eight to ten applications at four-day intervals, without lowering the predator population. There are materials that leave several key predators alive after the fir s t or second application but are no better than standard products a fte r four or five applica tions. Calcium arsenate leaves many im portant predators alive after several applications. However, the number of predators left alive may not be enough for bollworm control, and following the con tinuous use of this insecticide, bollworm populations will often increase. Furthermore, calcium arsenate allows aphids to increase. It kills boll weevils but does not control aphids or bollworms. There is some possibility of the selective use of specific insecti cides for the destruction of plant bugs, the cotton aphid, and thrips when they occur in destructive numbers. Trichlorfon (Dylox), at varied dosages, has been foundet al. by (85) Stern, and others to have selective toxicity favoring a wide range of predators. The widespread, unnecessary use of this insecticide in Arkansas, how ever, could be unfortunate, because many predators may depend for food upon the few plant bugs and thrips present early in the season. Deprived of sufficient prey, predators may destroy each other; for example, the big-eyed bugs sometimes k ill many of the insidious flower bugs in the cotton field. Demeton and Di-Syston may be used as in-furrow treatment at planting time. They control thrips, aphids, and spider mites on seedling cotton through systemic action without directly affecting predators. Aramite, chlorobenzilate, Kelthane, and tetradifon (Tedion) are acaricides that may be used fo r spider mite control without destroying insect predators. Spot treatment may cause no upset o f predator populations, even though predators in the treated spot are killed. An example of this is the use of Ethion and carbophenothion (Trithion) for control of spot infestation of mites. P redators of A r k a n s a s Cotton F ields 77

SUMMARY

Approximately 600 species of predaceous arthropods were found associated w ith cotton. They represented 45 families of in sects, 19 families of spiders, and 4 families of mites. A wide range of techniques was used in the investigation; however, direct field observations were basic and most successful. During the growing season, natural enemies of the boll weevil were of little consequence. However, insecticide applied against the boll weevil often upset the vital predator control of bollworms and spider mites. Dragonflies have often been underrated in studies on natural control; for example, the green jacket dragonfly destroys large numbers of bollworm, cabbage looper, and cotton leafworm moths. Among the mantids, grasshoppers, and crickets, predation appears to be a more widespread habit than previously reported. Green lacewing larvae, members of the Neuroptera or nerve-winged in sects, are among the most efficient predators. The predaceous bugs such as the insidious flower bug, big-eyed bugs, and nabids include some of the best known predators of the cotton field. The greatest number of predaceous species were found among the beetles, 120 species in all. Outside of the large families of Diptera, such as Syrphidae and Asilidae, comparatively little work has been done in Arkansas cotton fields on predaceous flies, although Mydaeidae, Empididae, Dolichopodidae, and Sciomyzidae are mentioned. The predatory habit is strongly developed in the Hymenoptera. The great number and wide distribution of ants make them a factor that must not be overlooked. For example, they attack the bollworm and the boll weevil from egg to adult. The extreme diversity in habits of the various species of wasps proved to be of practical value. A ll spiders are predaceous and supposed to be beneficial. There is not a single pest of Arkansas cotton that is not attacked by one or more species of spiders. However, they also feed freely on beneficial insects. On the one hand, spiderlings serve as much needed food fo r insect predators; on the other hand, they constantly compete w ith insect predators fo r food. The study of predaceous mites in the Arkansas cotton field has only begun. Four families are known to be present, but at least twice that many more may be found when all collected speci mens are identified. Representatives of two families of mites fed on bollworm eggs. To determine the efficiency of bollworm egg predators, boll worm eggs were placed in a cotton field at the rate of approximately 85 eggs per 100 plants or 125,000 eggs per acre. A fte r 24 hours, the 78 A r k a n s a s E x p e r im e n t S t a t io n, B u l l e t in 690 number of bollworm eggs per 100 plants dropped from 84.6 to 52.9, a reduction of 37.5 percent. Considering that almost three days pass before bollworm eggs hatch, the figure of 31.7 eggs destroyed or missing per 84.6 eggs each 24 hours is startling. This figure obviously would increase or decrease, depending on the number of predators present and on other factors. To determine the fate of the missing eggs, 531 predator feed ing observations were made. Ants carried away 119 eggs. Lady beetles destroyed 307 eggs, leaving no trace of egg shell in 246 cases. Piercing and sucking predators, on the other hand, left remains in most cases. Sources of predators appear to be important. Very few preda tors move directly from overwintering quarters to cotton; they usually pass the firs t few generations on early crops or weeds. Alfalfa, wheat, corn, Johnson grass, and sorghum are excellent sources of predators. Careful tim ing of insecticide application can help prevent ex cessive destruction of predators w ith broad-spectrum insecticides. I f fields are carefully scouted weekly, insecticide need be applied only when pest insects are present in destructive numbers. It must also be remembered, however, that predator populations may also be depleted by natural causes. Choice of insecticides that would k ill destructive insects only has limited potential for boll weevil and bollworm control but has possibilities against the cotton aphid, thrips, and plant bugs. In creasing predator populations in source fields, either by crop selec tion or by cultural methods such as supplementary irrigation, must await future investigations. P redators of A r k a n s a s Cotton F ields 79

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COLLOQUIAL NAMES AND THEIR SCIENTIFIC EQUIVALENTS, AS USED IN THE TEXT ambush bugs P h y m a ta spp. big-eyed bugs G eocoris spp. black and yellow garden spiderArgiope aurcmtia Lucas black hunter Leptothrips mali ( F itc h ) bowl and doily spider Frontinella communis (H e n tz ) bum ble bee B o m b u spp,. s carmine spider mite Tetranychus cinnabarinus (Boisduval) carpenter ant C am po n o spp.tu s cicada killer Sphecius speciosus ( D r u r y ) convergent lady beetle Hippodamia convergens Guerin-Meneville damsel bugs N a bis spp. eggplant tortoise beetle Nuzonia pallidula (Boheman) grasshopper m ite Eutrombidium trigonum (Hermann) great golden digger Chlorion ichneumoneum ( L in n .) green jacket dragonfly Erythemis simplicicollis (S a y ) green lynx spider Peucetia viridans (H e n tz ) green lacewings C h ry s o p spp. a horse guard B e m b ixCarolina (F a b r.) insidious flower bug Orius insidiosus (S a y) nine-spotted lady beetle Coccinella novemnotata H e rb s t organ-pipe mud-daubers T ry p o x y lo nspp. poison ivy spider Dapanus mirus (W a lc k .) six-spotted thrips Scolotlirips sexmaculatus (Pergande)1 spined soldier bug Podisus maculiventris (S a y ) spotted lady beetle Coleomegilla maculata (De Geer) star-bellied orb weaver Acanthepeira stellata (W a lc k .) s tilt bugs J a ly s u s spp. striped lynx spider Oxyopes salticus H e n tz triangle spider Hyptiotes cavatus (H e n tz ) wheel b u g Arilus cristatus ( L in n .) white tail dragonflies P la th e m is spp. yellow-legged mud-dauberSceliphron caementarium ( D r u r y )

1Accordingto Bailey (9), the six-spotted thrips that Scolothrips is known sexmaculatus as (Pergande) may be a complex of three or moreS . species,sexmaculatus including. 84 A r k a n s a s E x p e r im e n t S t a t io n, B u l l e t in 690

ACKNOWLEDGMENTS

To individually thank everybody who has contributed directly or indirectly to these investigations would be very difficult. Many people have contributed suggestions for techniques, made field observations, or have collected speci mens. Especially im portant has been the identification of thousands of insects, spiders, and mites.

W ithout the suggestions for techniques made by L. D. Newsom, C. Lincoln, M. H. Muma, H. Townes, H. K. Wallace, W. C. Rhoades, T. Leigh, E. V. W alter, O. Hite, and M. Hite, progress would have been much slower.

Those who made predator observations in cotton fields for two or more summers include G. Dowell, W. P. Boyer, L. Moore, R. A. Bell, P. Deema, R. C. Hunter, J. Trafford, and J. Isaza-R.

Special acknowledgment should be made of the advice and carabid identi fications given by H. Dietrich. Special thanks are due to H. Exline (Mrs. D. Frizzell) for her detailed assistance in spider taxonomy.

Acknowledgment should be made of the assistance in procuring determina tions given by W. H. Anderson and P. B. Dowden, of the Insect Identification and Parasite Introduction Research Branch of the United States Department of Agriculture, and by P. W. Oman and R. I. Sailer, form erly of this branch.

Included among those who identified insects taken in these investigations are: R. T. Allen, P. D. Ashlock, G. H. Bick, B. D. Burks, E. A. Chapin, W. S, Craig, R. R. Dreisbach, H. E. Evans, R. H. Foote, R. C. Froeschner, A. B. Gurney, F. C. Harmston, H. M. Harris, J. L. H erring, J. D. Hood, H. H. Knight, K. V. Krombein, C. H. M artin, F. A. McDermott, C. F. W. Muesebeck, K. O’Neill, R. H. Painter, S. Parfin, H. J. Reinhard, C. W. Sabrosky, R. I. Sailer, M. R. Smith, R. C. Smith, T. J. Spilman, W,. C. Stehr, H. K. Townes, L. M. Walkley, H. V. Weems, M. J. W estfall, C. W. Wingo, and W. W. W irth.

Included among those araneid taxonomists to whom thanks are due are: A. M. Chickering, C. D. Dondale, H arriet Exline, W. J. Gertsch, W. Ivie, H. W. Levi, M. H. Muma, and L. R. Roddy.

Specialists in the taxonomy of mites who aided in these investigations are: E. W. Baker, H. F. Cross, M. H. Muma, and I. M. Newell.

Acknowledgment should be made of the photographs and other illustra tions contributed by P. Deema, R. Adarve-R., J. Isaza-R., and G. Dowell.

Included among those who gave technical assistance on scientific names are R. Arnett, H. V. Weems, M. J. W estfall, M. R. Smith, and H. E. Evans.

Acknowledgment for aid in preparation of the manuscript is given to D. G. Whitcomb.