Characteristics: The striped lynx, Oxyopes salticus, and the green lynx, Peucetia viridans, are common spiders in cotton and are found throughout the Cotton Belt. The striped lynx is brown, about 1/4 inch long with 4 long, gray stripes behind the head on the front half of the body. The green lynx is a bright green spider about 1/2-3/4 inch long with small red spots on the legs and abdomen. Both species have eight eyes and two black lines running down the face and jaws, and the end of the abdomen is pointed. The legs are long and thin and armed with many long spines. They often run and jump erratically when disturbed.
Prey: Lynx spiders are probably the most important spiders in cotton because of their wide distribution and abundance. They are active and aggressive hunters that chase their prey or hide in wait and leap out. They do not build webs. Lynx spiders feed on a wide variety of insects, both pests (fleahoppers, bollworm/tobacco budworm larvae and eggs) and occasionally, beneficial insects. The striped lynx is a key predator of the cotton fleahopper.
General Biology: Spiders “balloon” into cotton fields by floating on wind-blown strands of silk. The egg-sac of the striped lynx is disc-shaped and attached to a leaf. The female guards the egg-sac until the spiderlings emerge. Reproduction occurs throughout the growing season and there are one or two generations per year. The green lynx produces a straw-colored egg-sac in the fall and guards it until the spiderlings emerge about 4 weeks later. Immature spiders overwinter and mature in July and August. The life cycle from egg hatch to mature adult is about 300 days. There is one generation a year.
Celer Crab Spider
Characteristics: Crab spiders can be identified by their front legs which are much longer and more robust than the other legs, giving it a crab-like appearance. Crab spiders also move quickly backwards or sideways like a crab, facing their antagonist or prey. The celer crab spider is a common species in cotton. The color of the female ranges from dull to bright yellow to white. There is an X-shaped mark on the back. The male has red along the edges of its body. In some individuals, two black or red bands are present on the abdomen. Several other species of crab spiders are found in cotton, including M. formosipes, a large species which changes color to match its surroundings.
Prey: Crab spiders feed on many cotton pests and occasionally on beneficial insects. Crab spiders do not build webs but wait to ambush passing insects using their strong legs and venom.
General Biology: Celer crab spiders are found in other crops and uncultivated areas and are carried into cotton fields on strands of silk by breezes early in the season. There are 1 or 2 generations per year.
Characteristics: Jumping spiders have compact, rectangular bodies with short, powerful legs. Their eyes are organized into three rows. The front portion of their body is as large or larger than the rear portion (abdomen). They range in size from 1/8 to 1/2 inch. Color is highly variable depending upon species. Some species have bright iridescent scales that give them a metallic green or purplish appearance. A commonly seen species, Phidippus audax, is a large, black and hairy spider with a large white spot on its back. All jumping spiders have large eyes that provide excellent eyesight for visually locating and pursuing prey. True to their name, they quickly jump when disturbed or when attacking prey. Jumping spiders are found throughout the Cotton Belt.
Prey: Jumping spiders feed on a wide variety of pest insects and occasionally beneficial insects. Adults can capture large caterpillars and boll weevil adults and are important predators of fleahoppers. Jumping spiders will also feed on moth eggs.
General Biology: Jumping spiders have excellent eyesight which they use to stalk and capture their prey with a sudden pounce. Females place their egg sacks inside nests of silk and remain with them until the spiderlings hatch and disperse. One generation is completed each year
Characteristics: Adults are delicate, slender insects 1/2 to 3/4 inch long, green with golden eyes and long antennae. The large, delicate wings are laced with a network of veins and are held roof-like over the back. Larvae are alligator-shaped, grayish-brown with long sickle-shaped mandibles projecting from the head. Full grown larvae are 1/2 to 3/8 inch long. Eggs are laid singly on top of a fine thread attached to leaves or stems except those of C. nigricornis which are also attached to stalks, but are deposited in a large, tight cluster. Adult Chrysopa species release a pungent odor when handled. C. carnea is found throughout the Cotton Belt while C. rufilabris is found from Texas eastward. Various other species of Chrysoperla and Chrysopa can be found in cotton.
Prey: Lacewing larvae are important predators of aphids, mites, whiteflies, and eggs and small larvae of bollworms, budworms, armyworms, and loopers. They also feed on other lacewing larvae. Lacewings become very abundant when aphids are present. Like their larvae, adult Chrysopa species also feed on insects, while adults of the Chrysoperla species feed only on honeydew, nectar and pollen.
General Biology: Eggs hatch in 3-6 days. Larvae feed for 2 weeks and then spin spherical, white cocoons of tough silk which are found behind bracts and in plant terminals. Larvae pupate inside the cocoons and the adults emerge in about 2 weeks. Adults fly at night and may travel several miles during the first 2-3 nights after emergence. Females lay their first eggs 4-6 days after emergence, produce a total of 200-800 eggs, and live for several weeks. C. carnea and C. rufilabris overwinter as adults while Chrysopa nigricornis and oculata overwinter as pupae in cocoons.
Characteristics: Adults are similar in appearance to the adult green lacewing but are smaller, brown and appear to be hairy. Larvae are reddish-brown with two to four white spots in the middle of the body. Like green lacewing larvae, they are alligator shaped with long, sickle like mouthparts used to suck juices from their prey. Brown lacewing larvae have a characteristic side-to-side “head-wagging” behavior which also distinguishes them from green lacewing larvae. Brown lacewings can be found throughout the Cotton Belt.
Prey: Adults and larvae feed on aphids and whiteflies. Larvae have been observed feeding on a variety of pest eggs, including bollworms, budworms, loopers and armyworms.
General Biology: Unlike the green lacewing, brown lacewing eggs are not placed on a stalk. Eggs are laid on the underside of leaves and turn from a cream color to pink or purple before hatching. Full grown larvae pupate inside an elliptical cocoon in concealed locations, such as within bracts. The cocoon consists of loosely woven silk through which the pupa is visible. Adults fly during the evening and at night. Brown lacewings tend to be more abundant when weather conditions are cool, when rain is frequent, and when the plant canopy closes. Most species have 2 or 3 generations per year.
Carabidae: Calasoma species
Characteristics: Ground beetles are dark and shiny with long, slender legs and antennae, and prominent eyes. These beetles run quickly but many species are not commonly seen because they are most active at night. Immatures are worm-like predators with well developed legs and jaws. Both stages are active on the soil surface or may climb into the plant canopy in search of prey.
Prey: Adults and larval ground beetles hunt caterpillars, including cutworms and bollworms that drop to the soil to pupate, and other insects in the soil. Some species such as Lebia climb the cotton plant in search of caterpillars. Tiger beetle adults feed on the same types of prey as ground beetles. Larval tiger beetles feed on insects active on the ground.
Seven-spotted Lady Beetle or “C-7”
Characteristics: The seven-spotted lady beetle is a large (1/3 inch long), orange-red lady beetle with seven, distinct dark spots on the forewings (back). The shield behind the head (pronotum) is black with a white mark on each side. Larvae are alligator-shaped and black with an orange-white strip down the middle of the thorax (central body region where legs are attached). Full grown larvae are about 1/2 inch long. This species is found throughout the eastern U.S. west to Oklahoma and Texas.
Prey: Both adults and larvae feed primarily on aphids but will also prey on eggs and caterpillars of various moth pests. Like the convergent lady beetle, the seven-spotted is most abundant in cotton when aphids are present. Adults can survive on pollen and nectar when aphids are absent.
General Biology: This species was introduced into the U.S. from Europe. Eggs are yellow-orange, football-shaped and laid on end in groups of 10-30. Each female can deposit up to 1,000 eggs during a 6-8 week period. Eggs hatch in 7-10 days. Larvae are full grown in 10-50 days, depending on temperature and availability of food. Pupae are black with spots of yellow. Adults emerge in 3-10 days. The life cycle is completed in about 2-3 weeks, and there are several generations each year. Small groups of adult beetles gather in protected areas to overwinter.
Harmonia or Asian Lady Beetle
Characteristics: Adults are a bright yellow-orange to reddish orange to red. The number of spots varies from 0 to 20. A black “M” shaped mark or solid mark in the center of the white pronotum (shield-like area just behind the head) identifies the harmonia or Asian lady beetle. The two large white areas on each side of the pronotum create the appearance of two large “eyes.” Larvae are alligator-shaped, black, with an orange jagged streak or blaze on each side of the abdomen. Eggs are yellow, football-shaped and laid in masses of 10-30 on leaves. H. axyridis is found throughout the southeastern U.S. to central Texas.
Prey: Both adults and larvae feed primarily on aphids but also feed on armyworm eggs and small caterpillars.
General Biology: The harmonia lady beetle was introduced into the U.S. to control aphids on pecan trees. It commonly moves into cotton when cotton aphids are abundant. Eggs hatch in 4 days and larvae feed for about 2 weeks and then enter the pupal stage. After about 6 days, the adult emerges. Females begin laying eggs 7-12 days later and each can produce 500-700 eggs. Adults live 30-80 days under laboratory conditions. Adults overwinter in masses in protected areas, sometimes becoming a nuisance in homes.
Convergent Lady Beetle
Characteristics: The convergent lady beetle is named for the two white lines on the pronotum (plate behind the head) that, if extended, would converge. The margin of the pronotum is also lined with white. The number of black dots on the adults ranges from only a few up to 13. Larvae are alligator-shaped and black with rows of orange spots. Eggs are bright yellow, football-shaped and laid in clusters of 10 or more on plants or on debris on the soil. Pupae are immobile, attached to the plant. The convergent lady beetle is found throughout the U.S. and is one of the most common lady beetles in cotton.
Prey: Adults and larvae feed primarily on aphids. When aphids are not available, adults feed on bollworm and budworm eggs and small larvae. Convergent lady beetles and larvae become very abundant when aphids are present. Adults also feed on nectar and pollen.
General Biology: Females lay 200-1,000 eggs during a 1- to 3-month life span. Eggs hatch in 3-4 days and larvae feed for 2-3 weeks and then enter the pupal stage. Pupae are immobile and attached to stems and leaves. Adults emerge from the pupae in about a week. There are several generations per year. Adults congregate in sheltered sites to overwinter.
Pink Spotted Lady Beetle
Characteristics: The pink spotted lady beetle is a slender, pink beetle with six very large black spots on each forewing. The spots sometimes join. There are two large triangular black marks on the area just behind the head. Larvae are alligator-shaped and black with cream or yellow spots. Eggs are yellow and football-shaped and laid on end in masses of 10-30. The pink spotted lady beetle is found throughout the eastern half of the U.S. to east Texas and only along the southern border of west Texas, New Mexico, Arizona and California.
Prey: Adults and larvae feed primarily on aphids but may also feed on eggs and small caterpillars. Adults feed heavily on pollen and may become abundant when cotton is blooming.
General Biology: Adults emerge from overwintering sites in the spring and lay egg masses on leaves often near aphid colonies. Females lay several hundred eggs during a 2-3 month period. Larvae feed for several weeks and then molt to the pupal stage. The pupa is attached to a leaf or stem and does not move. The adult beetle emerges from the pupa in about a week. There are several generations each year, and adults overwinter in protected sites.
Characteristics: These are active, soft-bodied beetles. They are dark blue with orange spots or stripes. C. quadrimaculatus is often called the ‘red-cross’ beetle because of the orange-red cross on its back. C. vittatus is dark blue with an orange stripe on each side. The front section of the thorax of these beetles is often orange and may or may not have a central dark spot. Larvae have a pincher-like structure at the tip of the abdomen and are rarely seen. In California and Arizona, C. marginellus and C. vittatus are important species in cotton.
Prey: Adults feed on moth eggs and small caterpillars, aphids, whiteflies, spider mites, aphids and stink bug eggs. C. quadrimaculatus commonly feeds on bollworm eggs and larvae. In Arizona, C. vittatus feeds on whiteflies in cotton.
General Biology: Eggs are yellow to pinkish-orange and spindle-shaped. Most eggs are laid in clusters on soil debris but sometimes are found in the plant terminal. Larvae are pink to brownish-red and feed on insects in the soil. These beetles overwinter as adults.
Characteristics: When viewed from the side with a hand lens, the hooded beetle is easily recognized by the horn-like projection which extends over its head, creating a “hood.” These small, ant-like beetles are tan or reddish with black patches, often forming zig-zag patterns on the back (elytra).
Prey: Feeding habits of this insect in cotton are not well known. Adults feed on nectar, and under laboratory conditions, readily feed on budworm and bollworm eggs and small larvae.
General Biology: Adults are often found hidden behind bracts on squares or nestled in terminals. Larvae live in sandy soil. They are believed to complete several generations a year and overwinter as adults.
Characteristics: The striped earwig is a slender, flattened insect 3/4-1 inch long with large pinchers at the tip of the abdomen. The two lengthwise stripes on the front of the thorax (pronotum) help identify L. riparia. Immature earwigs resemble adults but are smaller. Earwigs are active at night and search for food both on the soil and on plants. During the day they hide in soil crevices and thus are seldom seen. L. riparia is found along the East Coast to Florida and west to California.
Prey: Earwigs feed on eggs, larvae, and pupae of many different kinds of moths and beetles.
General Biology: Females deposit eggs in nests constructed in the soil and care for the eggs and nymphs. Development of egg to adult requires about 4 months, and there are 1 or 2 generations per year.
Characteristics: Adults are tiny to small, black to brown slender beetles which run and fly rapidly. The wings are very small, leaving much of the abdomen exposed. The tip of the abdomen may be curled forward, much like a scorpion, when the beetles are disturbed, although the beetles have no stinger. Adults are sometimes found in cotton flowers. Larvae are elongate with well developed legs.
Prey: Adults and larvae feed on a variety of small, soft-bodied insects and insect eggs. Some species feed on aphids, others on caterpillars or spiders. Little is known about the species present in cotton. Larvae commonly live in the soil and larvae of some species are parasites of insects.
General Biology: The rove beetle family contains a large number of species. Little is known about most species, especially those found in cotton.
Characteristics: Damsel bugs, also called nabids, are slender, dull tan to gray, sometimes black, insects about 3/8 to 1/2 inch long with long antennae and legs, and prominent eyes. Damsel bugs are shaped like some assassin bugs but are smaller and less colorful. Like assassin bugs, damsel bugs have a narrow head and a long beak and can inflict a painful bite. However, unlike assassin bugs, the damsel bug’s neck is wider than its head. Nymphs look like small adults without wings. Damsel bugs of various species occur throughout the Cotton Belt.
Prey: Damsel bugs feed on moth eggs and small larvae, aphids, fleahoppers, lygus and tarnished plant bugs, whiteflies, mites and occasionally other predatory insects such as lacewing larvae, pirate bugs, and big-eyed bugs.
General Biology: Eggs are white and cylindrical, and are inserted into stems with only the egg’s end (or cap) visible above the surface. Eggs hatch in 8-12 days and nymphs develop in 3-4 weeks. Females produce 150-300 eggs. There are 2 or 3 generations per year and adults overwinter in a variety of sheltered areas.
Spined Soldier Bug
Characteristics: Adults of this stink bug are pale brown, about 3/8 to 1/2 inch long and look like other stink bugs. This insect is named for the single, large spine on each “shoulder.” Adults resemble members of the plant-feeding brown stink bug group (Euschistus) but the shoulder spines are more pronounced on the spined soldier bug than on most brown stink bugs. There are some pest species, however, that closely resemble this predator. The most reliable way to distinguish between plant-feeding and predatory stink bugs is to examine the straw-like mouthparts (beak). Flip the stink bug over and look at its mouthparts (see drawings). If the mouthparts are broad (roughly twice the width of an antenna) and stout, it is a predatory species. If the mouthparts are slender (about the width of an antenna) then it is a plant-feeding stink bug. Like other stink bugs, Podisus emits a strong odor when disturbed. Eggs of the spined soldier bug are metallic silver or gold, with a fringe or crown of hairs about the top. Nymphs are oval-shaped and black with bands of red, yellow-orange and cream on the abdomen. This predator occurs throughout the Cotton Belt.
Prey: Adults and nymphs feed primarily on caterpillars. Occasionally they may attack beneficial insects and spiders in cotton. Young nymphs often “gang up” on larger prey.
General Biology: Eggs are barrel-shaped and laid in tight clusters of 20-30 on leaves and twigs. Newly hatched nymphs remain clustered around the egg mass before dispersing. Young nymphs feed only on plant sap while older nymphs and adults feed on insects. Development from egg to adult requires about 3 weeks. Adults live 1-2 months and females deposit 200-300 eggs. Spined soldier bugs are more common when caterpillars are present.
Spined Assassin Bugs
Characteristics: Spined assassin bugs are slow moving, medium to large bugs (1/2 to 3/4 inch long) with a long, curved beak held beneath the body. The front legs are enlarged and spined for grasping prey, and spines are also present on the thorax. Color varies from black to reddish-brown. The head is narrow and antennae and legs are long and slender. Nymphs resemble adults but lack wings. When disturbed, these bugs will often arch back, pulling their forelegs up and back in a defensive posture. The spined assassin bug, Sinea diadema, is found throughout the Cotton Belt. Other species of Sinea that may be found in cotton include S. confusa, S. complexa and S. spinipes.
Prey: Assassin bug nymphs and adults eat a variety of prey including caterpillars, aphids and many other insects, such as lady beetle adults and spiders.
General Biology: Eggs resemble those of the leafhopper assassin bug — they are barrel-shaped and laid upright in tight clusters or in rows on leaves or stems. However, the top or cap of the egg may be shaped in bizarre shapes or ornamentations, unlike that of the leafhopper assassin bug. Eggs hatch in about 14 days, and nymphs require 25-35 days to complete development. Adults live 1-2 months and females lay up to 300 eggs. These predators typically sit and wait to attack passing prey.
Leafhopper Assassin Bug
Characteristics: This assassin bug, Zelus renardii, is slender, about 1/2 inch long, and yellowish-green to red and brown in color. The head is very narrow and is armed with a large, strong beak. The nymph resembles the adult but is smaller and lacks wings. Other related assassin bug species include Zelus exsanguis, Z. cervicalis, Z. socius, Z. tetracanthus and Z. bilobus.
Prey: Assassin bugs attack moving prey and both adults and nymphs eat a variety of insects, both pest and beneficial. Assassin bugs are one of the few predators in cotton that can capture large caterpillars and adult boll weevils.
General Biology: Eggs are dark shiny brown with white caps and laid in tight clusters on cotton plants. The front legs of nymphs and adults are coated with a sticky substance believed to be used for capturing prey. They often have debris stuck to these legs. These predators are usually only abundant after mid-summer.
Characteristics: Adults and nymphs have broad heads and large, bulging eyes. Geocoris punctipes is common throughout the Cotton Belt. Adults of Geocoris punctipes are about 3/16 inch long and silvery grey. Adults of Geocoris uliginosus are smaller (1/8 inch long), oval and black to reddish-black. Geocoris pallens is slender, varies in color from buff to yellow-brown to black and is found from Arkansas to California. Nymphs of all species look like small adults without wings and can be mistaken for chinch bugs. Big-eyed bug nymphs, when crushed, release a strong, offensive “stink bug” odor. Both adults and nymphs run rapidly with a distinctive “swagger” and often fall from the plant when disturbed.
Prey: Big-eyed bug adults and nymphs feed on many insects, including bollworm and budworm eggs, small caterpillars, whiteflies, plant bugs, aphids and mites. The also feed on cotton nectar and occasionally plant sap.
General Biology: Eggs are deposited singly and are easily seen on leaves and stems of the cotton plant. Eggs are grayish-white to pink and shaped like a hot-dog. A bright red eyespot develops a few days after the egg is laid. Eggs hatch in 5-8 days. Development from egg to adult requires about 3-4 weeks. Females produce 150-300 eggs and live 3-4 weeks. All species overwinter as adults.
Hover or Syrphid Fly
Characteristics: The larva is a green to brown slug-like maggot with no legs. The tiny head is located at the small end of the tapered body. Although they have no legs, larvae can move well, stretching out their bodies in a looping action. Full grown larvae are about 1/4-1/2 inch long. Adults vary in size (from 1/4 to 1/2 inch long) and are striped with bright yellow and black. Some species have a slender, striped body, while others have a broad, striped abdomen and look like a bee. When at rest, the wings are held out at an angle from the body, unlike bees and wasps which fold their wings over their backs. Adults fly quickly and can often be seen hovering near plants and flowers, hence their common name.
Prey: Hover fly larvae pierce their prey and suck out the body fluids. They commonly feed on aphids, but may also consume moth eggs and sometimes small caterpillars. The adult flies feed only on nectar and honeydew.
General Biology: Eggs are white, sculptured, and elongate, and are laid on leaves near aphid colonies. Larvae swing their heads from side to side until they touch and seize an aphid. The larva then lifts the aphid into the air and holds it the while the aphid is sucked dry. Larvae feed for 2-3 weeks and large larvae can eat as many as 50 aphids per day. Larvae feed at night and rest near aphid colonies during the day. The pupa is pear-shaped and fastened to leaves, stems, or ground debris. The winter is spent in the pupal stage. Hover flies are most abundant when aphid numbers are high.
Characteristics: These are small (1/8 inch), slender flies with long, stilt-like legs. They are metallic blue, red or green and are often seen resting on leaves in the sunlight. They move rapidly on and among leaves, running and flying quickly. The wings are typically held out from the body at about a 45 degree angle.
Prey: Adult flies and larvae feed on small insects. Long-legged flies are not known to be an important predator of any cotton pest but are often noted in the field.
General Biology: Very little is known about this insect family. Adults are predaceous on other small insects, and the larvae are also assumed to be predaceous, although this is not known for most species. The adult flies can be very abundant, particularly from mid-season to harvest.
Minute Pirate Bug
Insidious Flower Bug
Characteristics: The insidious flower bug is more common in the Southeast and mid-South while the minute pirate bug is the dominant Orius species in the Southwest. Their distributions overlap through central Texas and Oklahoma. Adults are very small, 1/8 inch long, flat and oval shaped. They are black with a white X pattern on the back and have a prominent, forward projecting beak. Adults of the minute pirate bug typically have a black clavus (“V” shaped mark on back) and a faint gray spot on the wing membrane. Insidious flower bug adults have a white clavus and light yellow-tan wings. Young nymphs of both species are yellow-orange with a distinct orange scent gland on the abdomen. Older nymphs are tan to dark brown. Adults and nymphs run quickly.
Prey: Adults and nymphs use their beaks to pierce and suck the fluids from thrips, mites, aphids, whiteflies, and eggs and small larvae of budworms, bollworms, loopers, and armyworms. Orius are very effective egg predators. Both species also feed on pollen.
General Biology: Eggs are inserted in leaves and other soft plant tissue and hatch after 3 days. Nymphs become adults in 12-20 days; adults live 2-3 weeks and females lay about 100 eggs. Both species move into cotton early in the season to feed on thrips and spider mites. Later in the season they are often found in terminals and blooms.
Scymnus Lady Beetle
Characteristics: Scymnus lady beetles are very small, dull orange to brown beetles. One species, S. loewii, has a black center line forming a “V” pattern on the wing covers. Larvae are covered with long, white streamers of wax. These fuzzy, white larvae are sometimes confused with mealybugs. Species of Scymnus are found throughout the Cotton Belt.
Prey: Adults and larvae feed primarily on aphids, but may also feed on spider mites in cotton.
General Biology: Eggs are tiny, barrel-shaped and golden and laid singly in tight spots on the plant such as at the base of cotton leaves where the hairs are dense. Eggs hatch in 3-4 days and larvae develop in 14-17 days. Pupae resemble larvae in that they are covered with wax but unlike larvae do not move. Adults emerge from pupae after 5-8 days and live 3-6 weeks. There are typically 2 or 3 generations per year in cotton and numbers are greatest when aphids are present. The wax covering may provide Scymnus larvae some protection from fire ants as they are not attacked by ants as readily as other aphid predators.
Stethorus Lady Beetle
Characteristics: The adult is jet black and very small, about the size of a pinhead and commonly seen in spider mite colonies. The adults run rapidly when disturbed. Larvae are dark brown to black and covered with fine hairs.
Prey: Both adults and larvae feed on spider mites and their eggs.
General Biology: Stethorus lady beetles appear in cotton when spider mites are present. Eggs are laid in spider mite colonies.
Characteristics: The red imported fire ant is a reddish-brown to black ant identified by its very painful sting which results in the formation of an itching, white pustule. The size of workers is ranges from very small to large ants.
Prey: Fire ants are voracious predators of bollworm and budworm eggs and small caterpillars, fleahoppers, boll weevils and other insects. Fire ants often search cotton plants during the night and thus go unobserved. Fire ants quickly recruit nest mates to overcome large caterpillars and other prey. Fire ants are the only insect predator of boll weevil larvae and will chew into fallen squares to butcher and carry away weevil grubs. However, fire ants readily feed on aphid honeydew and “farm” aphids by driving away or killing predators and parasites that attack aphids. As a result, large numbers of fire ants can contribute to increases in aphid infestations. Fire ants probably have little impact on populations of predatory insects or spiders in cotton, except those feeding on aphids.
General Biology: Imported fire ants reside in large colonies in the soil consisting of 100,000 to more than 500,000 ants. Colonies may construct large mounds, especially after rains. During dry weather, mounds may not be visible. Fire ants may be more abundant along field margins and in reduced tillage fields where colonies escape cultivation.
Characteristics: Like plant-feeding species, the predatory six-spotted thrips is a tiny (1/16 inch), slender straw colored insect with short antennae. It is named for the six black spots on its wings which are held folded above the abdomen. Larvae lack wings and are white to yellow and cigar-shaped. The six-spotted thrips is commonly found in spider mite colonies.
Prey: Adults and larvae feed on plant-feeding spider mites and their eggs. Six-spotted thrips are well adapted to penetrating the silk webbing made by plant-feeding mites and have been credited with reducing spider mite outbreaks in some years. In laboratory studies, females killed more than 1,700 mite eggs during their 45-day lifespan.
General Biology: Eggs are inserted into leaf tissue and hatch in about 7 days. Larvae feed for about 5-6 days and then enter the pupal stage in the mite colony. Development from egg to adult requires about 2 weeks.
Parasites, Parasitoids and Diseases
Characteristics: The Tachinid fly, Archytas marmoratus, is a large, stocky fly about 1/2 inch long with long black bristles on its abdomen and thorax. The silvery-white “face” is characteristic of this species which is found throughout the southern U.S. Lespesia is a small (4-8 mm) gray fly which runs and flies quickly and is found throughout the Cotton Belt. Eucelatoria bryani is an active, grayish black fly about 1/4 inch long with a reddish tinge at the tip of its abdomen and is found from Mississippi west to Arizona.
Hosts: A. marmoratus is an important parasite of the larval stage of the bollworm, budworm, black cutworm, fall armyworm and related moth species in cotton, alfalfa and corn. Medium to large larvae, 4-5th instars, are most commonly parasitized. E. bryani is a parasitizes bollworm, budworm and fall armyworm larvae. Lespesia archippivora parasitizes many different kinds of caterpillars, including bollworm, fall armyworm, beet armyworm, cabbage looper and black cutworm.
General Biology: The adult A. marmoratus fly deposits maggots, rather than eggs, on cotton leaves where bollworms and budworms are feeding. The bluish-green maggots can lie in wait several days and quickly attach themselves to bollworms or other caterpillars that crawl within reach. The maggot penetrates the bollworm/budworm larva but does not begin to eat or develop. Parasitized bollworms continue to feed and develop normally. Once the bollworm or budworm has entered the soil and pupated, the fly maggot begins to consume the pupa. The maggot feeds for 6-10 days and then pupates. A single adult fly emerges about 8-10 days after the host pupates. A female can produce 2,000 or more maggots during her lifespan of 50-70 days. Winter is spent in the adult stage. Adults of Lespesia and Eucelatoria deposit their eggs or larvae in or on the host caterpillar.
Characteristics: Adults are large dark brown to black wasps about 1/3 inch long. The abdomen and legs are yellow to red and the wings are dark. The cocoons are off white to yellowish and smooth with long ridges. M. croceipes is found throughout the Cotton Belt except it is not reported from California.
Hosts: In some areas, M. croceipes is one of the most common parasites of bollworm larvae in cotton. All stages of larvae are attacked but 3rd and 4th instars are preferred. Budworm larvae are also parasitized. M. croceipes parasitizes bollworms infesting alfalfa, sorghum, tomato, wild hosts and corn in the whorl stage but not in the ear stage.
General Biology: The adult female stings the bollworm larva and deposits her eggs inside the caterpillar. Third instar larvae are most commonly parasitized. Larger larvae often drive off the parasite before it can sting. The wasp’s egg hatches into a grub which feeds inside the bollworm for about 8 days. The parasitized bollworm soon stops feeding. Once full grown, the wasp grub bores out of the dead bollworm and spins a white cocoon. The adult wasp emerges from the cocoon in about a week. Development from egg to adult requires about 15 days at 86°F. There are 3 or 4 generations per year and the wasps overwinter in the soil as mature larvae (prepupae) inside cocoons.
Characteristics: The adult wasps are about 1/4 inch long with long antennae and very dark wings. The head and thorax are black while the abdomen and middle and hind legs are red. C. nigriceps is sometimes called the “red-tailed” wasp because of the red abdomen. The ovipositor (stinger) is short and black and often not visible. This parasite is widely distributed across the southeastern Cotton Belt west to Oklahoma and Texas. These brightly colored wasps may be seen hovering about cotton plants in search of caterpillars to parasitize.
Hosts: C. nigriceps is one of the most important parasitoids of the budworm. It can only successfully parasitize budworm larvae and a related species, H. subflexa, which is not a cotton pest. Wasps will sting bollworm larvae but the parasite eggs do not develop and the bollworm survives. Also, beet armyworm larvae are occasionally parasitized by this wasp. All sizes of budworm larvae are attacked but late second and third instars are preferred.
General Biology: Adult female wasps sting budworm larvae and deposit eggs internally. Eggs hatch into grubs which feed internally for about 2 weeks. Small budworm larvae continue to grow once parasitized while those in the 4-5 instar do not. Once full grown, the parasitoid grub emerges from the dead budworm larva and spins a cocoon in the soil. The adult wasp emerges in about 2 weeks and lives for about 2 weeks. There are about 3 or 4 generations per year and wasps overwinter as pupae in the soil.
Characteristics: This small (1/8 inch) robust wasp has a small white patch on each side of the front of the abdomen C. insularis is found throughout the Cotton Belt.
Hosts: C. insularis parasitizes eggs of the bollworm, beet armyworm, fall armyworm and several other armyworm species.
General Biology: The female places her egg inside the bollworm or armyworm larva while the larva is still inside the egg. The larva hatches and develops normally for several days but soon appears shrunken and dry as the Chelonus larva feeds internally. The parasitized host larva then spins a fine-meshed, yellow silk cocoon, called the “death-cell”, around itself. About 2 days later the armyworm larva dies. A day later, the full grown Chelonus larva emerges from the shriveled body of the armyworm and pupates nearby.
Characteristics: The adult B. mellitor is a brownish-orange wasp about 1/16-3/16 inch long. The dark eyes, antennae and legs and the dusky areas on the wings give it a black appearance. The abdomen is broad and the female has a black ovipositor (stinger) almost as long as her body. Bracon mellitor is native to the U.S. and found throughout the Cotton Belt and northern Mexico. Bracon hebetor is a related species.
Hosts: B. mellitor parasitizes boll weevil grubs. It is often the most common insect parasite of the boll weevil. It also parasitizes other weevil species and some caterpillars, including the pink bollworm. Adult wasps feed on nectar produced at the base of cotton squares.
General Biology: The female Bracon mellitor searches cotton squares and bolls and probes the fruit with her ovipositor to detect weevil grubs inside. Once a grub is located, the female drills through the fruit and paralyzes the grub by stinging it. A single egg is then placed on the grub or nearby in the grub’s cavity. The egg hatches in a day and the tiny parasite larva pierces the paralyzed weevil grub and feeds on its body fluids. After 4-5 days, the parasite larva is full grown and it spins a white silk cocoon in which it pupates inside the weevil’s cell. The adult wasp emerges from the cocoon in about 3-6 days and escapes from the weevil’s cell by chewing through the square or boll. Female wasps live about 3 weeks and produce about 160 eggs each. Winter is spent as a mature larva (prepupa) inside the cocoon.
Characteristics: These are slender, elongate wasps (1/4 inch long), with mostly orange abdomens that are flattened on the sides. The abdomen is narrowly attached to the thorax. Cocoons are attached to leaves, are shaped like short fat sausages, and are typically banded in silver/grey and black. Although Hyposoter spp. are reported throughout the Cotton Belt, they are more prevalent from Texas westward.
Hosts: Hyposoter wasps attack a wide range of caterpillars, including bollworms, budworms and armyworms.
General Biology: The adult female attacks small caterpillars, laying a single egg inside. The parasite grub emerges from the larva after 8-10 days and spins a cocoon on the leaf. The adult parasite emerges from the cocoon 5-7 days later.
Characteristics: Cotesia marginiventris is a small wasp, about 1/8 inch long, slender and black. The white cocoons, containing Cotesia pupae, are commonly seen on cotton leaves. The cocoons are solitary and resemble a fuzzy grain of rice attached to the leaf.
Hosts: Cotesia parasitizes larvae of bollworms, budworms, loopers and beet, fall and southern armyworms in cotton and other field crops. This parasite is particularly effective against beet armyworms.
General Biology: The adult wasp lays her egg inside the host caterpillar. The egg hatches in 1-2 days and the parasite grub feeds inside the caterpillar for about 6 days. The full grown grub then bores out of the caterpillar, causing it to die, and spins a white cocoon around itself. The adult wasp emerges from the cocoon about 4-5 days later. A single female can parasitize (kill) 200-300 host caterpillars during its 10- to 14-day life. There may be 4 to 6 generations per year.
Braconidae: Meteorus species
Characteristics: The adult is a golden brown, slender wasp about 1/4 inch long. Females have a long stinger (ovipositor) projecting backward from the abdomen about the length of the abdomen. Cocoons are brown, about 1/3 inch long, shaped like a football and are suspended from the leaf on a filament.
Hosts: Meteorus attacks a wide range of caterpillars, including beet, fall and southern armyworms in a variety of crops and wild plants.
General Biology: Meteorus females lay eggs in nearly all larval stages of their hosts, although small larvae are most frequently parasitized. After feeding internally for 10-12 days, the parasite grub emerges from the host and spins its football-shaped cocoon while suspended from the leaf on a silken thread. The adult lives 3-6 weeks and is capable of parasitizing 150-300 hosts during its lifetime. There appear to be 3 or 4 generations per year.
Characteristics: Lysiphlebus testaceipes is a shiny, slender black wasp about the size of a cotton aphid. Wasps can often be seen in aphid colonies as they sting (parasitize) aphids. More commonly, the parasitized aphid mummies are seen, evidence this parasite is active in the field. Aphid mummies are dead swollen aphids stuck to leaves. The mummies are tan to gold and contain a developing wasp or have a hole cut in the top through which the wasp emerged.
Hosts: L. testaceipes attacks the cotton aphid in cotton and other aphid pests such as greenbugs in wheat.
General Biology: The female pierces (stings) the cotton aphid and deposits an egg inside. The egg hatches in about 2 days and the parasitoid grub feeds internally on the living aphid. The grub is full grown in about a week at which time the aphid takes on a swollen, tan appearance and dies. The parasitized aphid is termed a “mummy” and is attached to the leaf. The grub enters the pupal stage and about 4-5 days later, the adult wasp emerges through a circular hole cut towards the back of the aphid mummy. Development from egg to adult requires about 2 weeks. A single female can parasitize about 100 aphids during her 4- to 5-day life span.
Encyrtidae: Copidosoma species
Characteristics: This tiny (1/16 inch) shiny black wasp resembles a small fly. Looper caterpillars parasitized by Copidosoma are most easily recognized after they spin their pupation cell on the underside of leaves. Unparasitized loopers form a green pupa that later darkens to brown. Parasitized loopers, in contrast, fail to pupate, but instead elongate, causing the head to fold into a hook shape under the body. The larva takes on a cream or light tan color, and appears to be made of styrofoam. Each of the “foam” cells in the caterpillar’s body is actually a developing wasp. These parasites are found throughout the Cotton Belt.
Hosts: These wasps attack soybean loopers and other looper caterpillars.
General Biology: Adult wasps sting looper eggs, laying a single egg in the host egg. After the looper hatches, the nucleus in the wasp egg divides repeatedly and each nuclei becomes a wasp larva. Up to 2,000 wasps can develop in a single host looper. The parasitized looper requires a bit longer to develop than an unparasitized looper and eats up to 50 percent more foliage than an unparasitized looper. Development from egg to adult requires about 17-27 days and there are 2 or 3 generations per year. A single female is capable of parasitizing 10-30 loopers. Late in the season, these parasites can practically eliminate a soybean looper population in a single generation.
Stink Bug Egg Parasites
Family Scelionidae:Telenomus species
Characteristics: These are tiny (1/20-2/20 inch), shiny black wasps with antennae that are elbowed downward. The wings have very little venation. The shape of the body varies from slender and somewhat flattened top to bottom, to short and very stout. These parasites are found throughout the Cotton Belt.
Hosts: These wasps parasitize eggs of different stink bug species, including predaceous stink bugs in some cases. The species of stink bug attacked depends on the parasite species. Some attack many species of stink bugs while others parasitize only a few species. Trissolcus basalis is an important parasite of the southern green stink bug which can be a pest of cotton.
General Biology: The parasite females lay their eggs in the eggs of the stink bug, usually only one parasite egg per host egg. A single wasp develops in each egg. Parasitized stink bug eggs turn black within a few days of parasitism. The adult parasite emerges from the egg about 8-20 days after the parasite egg is placed in the stink bug egg. Adult parasites live about 2-6 weeks and can parasitize from 30 to over 100 stink bug eggs in a lifetime.
Family: Aphelinidae: Eretmocerus species
Characteristics: Although these wasps are very tiny, about 1/25 inch long (1 mm), they are among the most important natural enemies of whiteflies. Because of their small size, adults are rarely seen. However, whitefly nymphs parasitized by these wasps can be identified by the circular hole cut in the top of the nymph through which the adult wasp escaped. Whitefly nymphs parasitized by some Encarsia species turn black while those parasitized by Eretmocerus do not. Both Eretmocerus and Encarsia are distributed throughout the Cotton Belt but the range of individual species is variable and often unknown. Eretmocerus spp. near californicus is an important native species in the Southwest. Encarsia pergandiella is an important native species while E. formosa is introduced into the U.S.
Hosts: These wasps parasitize nymphs of whiteflies. Adult wasps also act as predators as they sting whitefly nymphs, creating a hole and feeding on the body fluids that flow out.
General Biology: Adult wasps search for whitefly nymphs and lay an egg in the nymph (Encarsia) or under the nymph (Eretmocerus). The wasp larva feeds internally, killing the whitefly nymph. The parasite larva then pupates and later the adult wasp escapes through a hole cut in the top of the whitefly nymph. In contrast, whitefly pupae from which an adult whitefly emerged have a “T” shaped slit in the pupal skin. Nymphs parasitized by Eretmocerus are a dark amber color compared to the lighter colored healthy nymphs. Development from egg to adult requires 18-25 days for Eretmocerus and somewhat less for Encarsia. A single female wasp parasitizes 40-50 whitefly nymphs and kills many other nymphs by direct feeding.
Family: Mymaridae: Anaphes iole
Characteristics: These very tiny wasps, less than 0.04 inch (0.6mm), have very slender hind wings. They may be captured in yellow pan traps or with sweep nets made of canvas or reared from lygus bug eggs collected from cotton and alfalfa. Parasitized lygus eggs are black. Anaphes iole is known to occur in Louisiana, California and Arizona and is probably present throughout most of Cotton Belt.
Hosts: Anaphes iole is an important parasite of eggs of the lygus bug, Lygus hesperus and the tarnished plant bug, L. lineolaris. A. iole also parasitizes eggs of some species of damsel bugs in beans. However, studies in the Southwest showed A. iole did not attack damsel bug eggs in cotton.
General Biology: The adult parasite deposits her egg into the lygus eggs which are inserted into plant tissue. The wasp egg hatches into a grub which consumes the contents of the lygus egg and pupates. A single adult wasp later emerges from the lygus egg. Development from egg to adult requires about 15 days.
Characteristics: Trichogramma are extremely tiny wasps which develop inside the eggs of moths and butterflies. Adults are rarely seen in the field because of their small size. However, eggs of bollworms and budworms which are black indicate the presence of Trichogramma wasps. A powerful hand lens or microscope is necessary to clearly see these minute parasites. Adults are yellow and brown and the wings have only a few veins. T. pretiosum is found throughout most of the Cotton Belt. T. exiguum has been reported from Alabama, Arkansas and Texas and may be present in other areas also. Identification of the species requires high magnification and specialized training. Bollworm/budworm eggs also turn black when parasitized by another tiny wasp named Telenomus heliothidis (Scelionidae). Telenomus adults are uniformly shiny black.
Hosts: Trichogramma parasitize eggs of bollworms, budworms, loopers and other caterpillar pests. Some species also parasitize eggs of green lacewings. Trichogramma rarely parasitize beet armyworm or fall armyworm eggs which are covered by scales left by the female moth.
General Biology: The adult female places one or more eggs inside the host egg using her “stinger” (ovipositor). The egg(s) hatch in a day and the wasp larvae feed inside the egg for about 3 days and then pupate inside the host egg. At this time, dark deposits on the inside of the host egg cause it to turn black. After 4-5 days, the adult wasp cuts a hole in the side of the host egg and emerges. Development from egg to adult requires 8-10 days. Adults live about 10 days. Trichogramma will parasitize all stages of bollworm/ budworm eggs except those within a few hours of hatch (black-head stage). Adults are active throughout the season. Immature stages overwinter in host eggs and adults are active during warmer days of the winter in southern climates.
Cotton Aphid Fungus
Characteristics: Cotton aphids recently killed by this fungus are covered with a velvety white or light gray growth. Soon, other fungi begin to appear on the dead aphid, giving it a fuzzy olive-brown appearance. Fungus-killed aphids should not be confused with aphid “skins” which are white and shriveled or with parasitized aphids. N. fresenii is found from Georgia to central Texas.
Hosts: N. fresenii is the most important pathogen of the cotton aphid in the mid-South and Southeast. Widespread outbreaks of this fungus, called epizootics, often occur when aphid numbers are high and can eliminate aphid infestations in 7-10 days. These epizootics can occur during relatively dry weather. This fungus only attacks aphids.
General Biology: Cotton aphids infected with N. fresenii produce fungal spores which land on leaves. The sticky spores attach to the legs of aphids as they walk across leaves. Once the spores contact an aphid, they germinate and penetrate the aphid’s body. The fungus grows internally and the aphid dies in 3-4 days. The fungus then grows outside the dead aphid and later tiny spores are released and carried on the wind. A single aphid can release 3,000 spores and up to 60,000 spores per cubic meter of air have been reported at night in cotton fields during epizootics. The fungus completes its life cycle in 3 days, allowing rapid increase in the number of infected aphids. Cotton aphid infestations often crash 7-10 days after aphids killed by N. fresenii are found in a field. Careful scouting to detect the fungus earlier can be used to predict epizootics and possibly avoid the need for aphicides. Resting spores survive in the soil. Winged aphids, infected yet still alive, can also carry the fungus.
Nuclear polyhedrosis virus
Characteristics: Caterpillars killed by NPV are discolored and limp. They often hang from leaves attached only by one or two legs and are easily broken open when handled, releasing a dark liquid. NPVs, also called baculoviruses, are found nearly everywhere. Different strains or “species” of virus occur and each tends to attack only a limited number of caterpillar species.
Hosts: NPVs infect more than 400 insect species. Caterpillars of moths and butterflies are commonly infected. In cotton, cabbage loopers are often attacked by NPV while beet armyworms, bollworms and budworms are less commonly infected.
General Biology: The liquid released from insects killed by NPV contains millions of virus particles which fall onto leaves. Other caterpillars ingest the virus particles while feeding on contaminated leaves and become infected. Virus particles can also enter through natural openings in the caterpillar, or be carried on the stinger (ovipositor) of a parasitic wasp. Two to five days after ingesting the virus, caterpillars become sluggish and eat less. Death follows in 5-12 days. Shortly before dying, the caterpillar may climb to the top of the plant and hang by its prolegs. The insect’s body wall is easily ruptured, thereby releasing liquid and virus particles onto leaves. Other caterpillars contact the virus and the cycle is repeated.
Beauveria and other Fungi
Characteristics: Insects killed by Beauveria become covered with a white, thick mass of fungal growth. The infected insect becomes stiff and if broken apart is found to be filled with a solid, fungal mass. Beauveria bassiana is found throughout the U.S. Erynia and Nomuraea are other fungal diseases of insects.
Hosts: B. bassiana attacks many different species of beetles, moth caterpillars and true bugs. In cotton, bollworms, boll weevils and a variety of other pest and beneficial insects are sometimes infected with this disease. Nomuraea and Erynia attack caterpillars.
General Biology: Spores (conidia) of B. bassiana and other fungi occur in the soil and are released from infected insects. Spores that contact the insect germinate and grow through the body wall or enter the insect’s body through natural openings. Spores which are eaten germinate on the insect’s mouth parts or in the digestive tract and grow into the insect’s body. The insect dies in a few days as its body is filled with fungal growth. The fungus then grows externally over the insect’s body and releases spores to infect other insects.