Insect Pests of Vegetables

by Kenneth A. Sorensen

North Carolina Agricultural Extension Service AG-404

Published 5/88

Placed on the Web 2/95 by the Center for Integrated Pest Management, NCSU


Contents


Click here to view chart depicting the Seasonal Destructive Activity of Selected Insects


Correctly identifying the insects and other pests that attack vegetables is the first step toward controlling these pests effectively. The pest descriptions in this booklet are designed to help the commercial vegetable grower and home gardener recognize the insects found on vegetables. Information on insect life cycles and habits is included to make pest control recommendations more understandable and usable. More specific descriptions of insects and detailed information on control procedures are available through local county Agricultural Extension Services offices.

Most of the insects considered common vegetable pests undergo a developmental process known as metamorphosis, which simply means that the insect changes form during its life. Metamorphosis may be complete or incomplete. Complete metamorphosis consists of four stages -- egg, larva, pupa, and adult.

All insect life cycles include an egg stage. The insect is immobile during this stage. A larva hatches from the egg. The larval stage is the growth stage and frequently the pest stage of insect life. This is especially true of moths, butterflies, and true flies. Larvae of moths and butterflies are commonly known as caterpillars. Maggots are the larvae of true flies. Many beetles exist as grubs during the larval stage. Larvae vary in size from as short as 1/8 inch to as long as 4 inches.

The larva molts, or changes and enters the pupal stage. As during the egg stage, the insect is immobile during this pupal or changeover period. It is during this stage that the insect develops into an adult.

Adults may or may not feed in the same way and on the same plants as larvae. Beetles, for example, have chewing mouthparts and, like many grubs (beetle larvae), are capable of causing great damage to vegetables. Moths and butterflies, on the other hand, have mouthparts designed for siphoning and are unable to damage plants.

Incomplete metamophorsis consists of three developmental stages -- egg, nymph, and adult. The egg stage is similar whether an insect undergoes complete or incomplete metamorphosis.

Immature insects called nymphs hatch from eggs. Nymphs damage plants and reduce vegetable quality by sucking plant juices. Some insects damage plants not only by extracting juice but also by injecting saliva into the plant. The best known example of this is the injury called hopperburn caused by the potato leafhopper on Irish potatoes.

The pests discussed in this booklet are divided into the following groups: Moths, Butterflies, and Their Young (Caterpillars); Beetles; Sap-Feeding Insects (True Bugs, Aphids, Leafhoppers, and Whiteflies); Flies; Other Insects; and Noninsect Pests.

Moths, Butterflies, and Their Young

Caterpillars, the larval stage of moths and butterflies, damage both the foliage and fruit of a number of vegetables. These insects chew holes in foliage and fruit and leave degrading excrement and silk on plants.

Cabbage Looper

This caterpillar feeds on the underside of leaves of cabbage and related crops and on lettuce, spinach, beets, peas, and tomatoes. It chews irregular holes through leaves. Moths lay greenish-white eggs on the upper surface of leaves. Larvae, or worms, are 1-1/2 inches long when full grown. Larvae are pale green with four thin, white lines along the back and a wide, pale line on each side of the body. These lines can be seen easily, even on small larvae. The head is narrower than the thorax (body sextion behind the head). The larvae move in a measuring or looping motion, thus the insect's name. When disturbed, loopers rear upwards. Larvae go into a resting or pupal stage in a flimsy, lace-like cocoon on the plant. The adult is a brown moth with silver markings on the wings. It has a wingspread of about 1-1/2 inches. There may be three or more generations per year, the number of worms increasing greatldy with each generation. Cabbage loopers do not overwinter in North Carolina. Moths from Georgia and Florida move into the state each year near the middle of May.

Beet Armyworm

Similar to the true armyworm, this insect is a general feeder and attacks foliage, stems, and sometimes roots of a wide variety of vegetables. Among plants attacked by this pest are beets, asparagus, corn, lettuce, cabbage, tomatoes, peppers, potatoes, onions, and peas. This pest is capable of destroying young plants. The beet armyworm overwinters as a pupa, emerging as an adult in the spring. The adult is a moth with a 1-1/4 inch wingspread. The moth's grayish brown front wings are marked with lighter lines and a spot near the center of the wing. Hind wings are white with brown edges and veins. Females lay between 500 and 600 eggs over a 4- to 10-day period. Irregular egg masses are covered with scales from the moth. Mature larvae are green with a prominent dark stripe along each side. Larvae have a dark spot on each side of the thorax, are 1-1/4 inches long, and pupate in the soil. In North Carolina, there are several generations a year.

Corn Earworm

(Also called Tomato Fruitworm and Bollworm)

This caterpillar feeds on a wide range of vegetables and, as a result, is known by several names. It may attack almost any vegetable but does the most serious damage to corn and tomatoes. Other vegetables attacked include peppers, eggplant, beans, okra, sweet potatoes, lettuce, and cabbage.

Fresh corn silk is preferred by this pest as a location to deposit eggs. Eggs may hatch as soon as two or three days from the time they were deposited. Newly hatched larvae feed on buds and leaves or on corn silks. When they are four or five days old, larvae travel down the silks and feed on kernels at the end of the corn ear. If fresh corn silk is unavailable, moths prefer laying their eggs on tomato foliage, especially when plants are flowering. Larvae attack tomatoes from the time the fruit forms until it ripens, boring into the sides of the fruit and near the stem. Sometimes a small, black entrance hole is the only visible sign that a large worm is inside a tomato. Injury to tomatoes is most severe in the late summer and fall.

When full-grown, larvae are about 1-1/2 inches long. They may be brown, green, or pink, with lighter colored longitudinal stripes. The head is yellow, and the underside of the body is always lighter than the back. Larvae enter the soil to pupate.

Moths are cream to grayish-brown, have green eyes, and are marked with a dark spot near each wing tip. They have a wingspread of about 1-1/2 inches. Hind wings are light colored with darker areas near the edges. Moths deposit yellow eggs one at a time on plants. One female can lay as many as 3,000 eggs. There are usually three and sometimes a partial fourth generation of earworms each year in North Carolina.

Cutworm

Many kinds of cutworms attack vegetables. Asparagus, cabbage, squash, and tomatoes are particularly vulnerable. Most cutworms cut off stems of plants at or near the soil. Cutworms feed at night when temperatures are 65 degrees F or higher. During the day these insects hide just beneath the soil close to the site of the previous night's damage. This pest is capable of damage sufficient to necessitate the replanting of corn. Cutworms usually do not eat plants beyond cutting through them, although some species climb stalks and feed on the upper parts of plants, which causes less damage.

When full grown, cutworms are 1-1/2 inches long. They curl up into a tight C shape when disturbed. Most cutworms are a dull color and have practically no hair. They pupate underground. Cutworms generally overwinter in the soil in the larval or pupal stage. Adults are dull colored moths with wingspreads of 1 to 1-3/4 inches. Hind wings are usually light in color. Moths lay eggs on the stems of grasses and weeds or on bare ground. There may be more than one generation of some species each year.

Diamondback Moth

Larvae of this moth feed during the cool parts of the growing season on the underside of leaves of cabbage and related crops. Larvae feed for a time after hatching as leafminers (see section on vegetable leafminers). As larvae grow, they begin feeding on the external portion of leaves and buds. Feeding holes do not penetrate the entire leaf. Larvae are greenish-yellow with black hair and are about 1/3 inch long when full grown. They wriggle actively when disturbed and drop from the plant on silken threads. Larvae pupate inside a lacy cocoon attached to the leaf of the host plant. Moths overwinter in debris of collards, cabbage, cauliflower, and related crops. They have a wingspread of about 1/3 inch. Moths are gray to brown, marked with white. When at rest the moth has white, diamond-shaped markings along the back. The hind wings are paler and have a fringe of hair on the rear margin. Moths lay small, white eggs either singly or in groups of three or four on leaves. There may be five or six generations per year in North Carolina.

European Corn Borer

This borer attacks many species of plants, but corn, peppers, and Irish potatoes are the vegetables most severely damaged. European corn borers feed on leaves and in protected areas until about half-grown, when they bore into a plant's stem or fruit. Nearly an inch long when full grown, the caterpillar is cream colored, has a brown head, and is marked with small, round, brown spots. Caterpillars molt into pupae inside the host plant. This insect overwinters as a nearly full-grown larvae in cornstalks at ground level. Adults are pale yellow moths with irregular dark bands running across the wings. The moth's wingspread is about 1 inch. Males are smaller and somewhat darker than females. Eggs are laid in groups of up to 50 on the underside of leaves and overlap to resemble small fish scales. Most of North Carolina sees at least two generations of this insect each year, while in the eastern part of the state, there are three generations most years.

Fall Armyworm

Like other armyworms, this insect may "march" from field to field. It often is called the shatterworm because of the destruction it causes to corn foliage. Larvae also damage corn ears as well as beans, potatoes, peppers, tomatoes, spinach, cabbage, and cucumbers. Swarms of moths move northward each spring from southern Florida and areas along the Gulf Coast. Females lay about 1,000 eggs each in masses of about 150. Eggs are usually laid on grass. Larvae are very small when they hatch but reach a length of 1-1/4 inches when full grown. Larvae vary in color from light tan to green or nearly black, are decorated with thin, yellow stripes, and have a prominent inverted white Y on the front of the head. Larvae go into the soil to pupate. Adult moths have dark gray front wings that are mottled with light and dark splotches. The wingspread of the adult moth is about 1-1/4 inches. Hind wings are grayish-white. Males have a white spot near each wing tip. It appears that this insect cannot overwinter in North Carolina. Most years there are many generations of the pest.

Imported Cabbageworm

(Also called Cabbage Butterfly)

This caterpillar attacks cabbage, cauliflower, kale, collards, mustard, radish, and turnips. Larvae riddle outer leaves with irregularly shaped, often large holes. Caterpillars are capable of doing enough damage to severely retard plant growth. Females lay one egg per leaf on the underside of leaves. Eggs hatch into caterpillars that are 1-1/4 inches long when full grown. Caterpillars are velvety-green and are decorated with three indistinct gold stripes, one along the back and one on each side. The pupal or chrysalid stage of the insect is brownish-grey and has many projections or spines. This insect is commonly found attached to a leaf during the pupal stage. Glue at the pupa's tail and a silken loop that encircles the middle of the pupa's body hold it in place. The adult is a white butterfly with one or two black spots on each wing. This pest overwinters as a pupa either on old plant refuse or on nearby posts or buildings. There are three or four generations per year.

Pickleworm

Pickleworm larvae bore into many cucurbit fruits. Cantaloupes, cucumbers, and squash are most seriously damaged. Caterpillars feed first on foliage. As the insect grows, it begins feeding on fruit. Pickleworms do the greatest damage to growing vine tips and blossoms early in the season. Larvae are initially white with black spots and have dark heads. There is a dark indention on each side on the back of the head. Larger larvae are up to 3/4 inch long and are green. Sawdust-like excrement produced by larvae can easily be seen extruding from damaged fruit. Winter is spent in the pupal stage in a silken cocoon on crop refuse in subtropical regions of the United States. Pickleworms usually appear in North Carolina in early July. The adult is a moth with a wingspread of about 1 inch. Wings appear fragile and are marked with pale yellow centers and yellowish-brown margins.

Potato Tuberworm

This caterpillar does significant damage feeding on exposed potatoes in the field, riddling them with narrow, silk-lined burrows. Adults are small, narrow-winged, grayish-brown moths with a wingspread of 1/2 inch. Moths tend to fly in late afternoon and evening. Females deposit single eggs on foliage of tomatoes, potatoes and related plants, or on exposed tubers of Irish potatoes. Eggs hatch into pinkish-white or green caterpillars with brown heads. When full grown, caterpillars are about 1/2 inch long. Larvae mature in about three weeks and pupate in gray, silken dirt-covered cocoons on the outside of the tuber. A brush of long dark scales protrudes at the end of the body. Moths deposit clusters of two to seven eggs on fruit, vines, buds, and leaves. There are at least four generations per year in North Carolina. Cultural control is possible by planting for early maturity and destroying plants immediately after harvest, thus preventing movement of the pest to later crops.

To prevent damage, potatoes should be kept covered with soil before harvest, and harvested potatoes should be stored in insect-proof areas. Also, vines should be cut, raked, and burned two or three days before harvesting. There may be several generations of this insect per year.

Squash Vine Borer

This borer can be very destructive to squash and pumpkin plants. By boring into a vine near the base, this thick, white, wrinkled brown-headed caterpillar causes entire plants to wilt. The larva overwinters 1 or 2 inches in the soil within a dark, dirt-encased cocoon and molts into a pupa in the spring. Within two or three weeks after molting, the 3/4-inch-long pupa has worked its way to the soil surface and emerged as an adult. The adult squash vine borer is a moth with a wingspread of about 1-1/2 inches. The front wings are covered with metallic, greenish black scales.

Hind wings are transparent. The abdomen is ringed with red and black. Squash vine borer moths look and act like paper wasps. Females lay red eggs near the base of plant stems. Eggs produce smooth, white caterpillars that bore into the center of the vine a few days after hatching. Small piles of green excrement and wilting of whole vines are signs a plant is infested with squash vine borers. There are two generations of this pest each year. Damage is usually noticed in early June and again in early August.

Tomato Hornworm and Tobacco Hornworm

Tomato and tobacco hornworms feed on tomatoes, peppers, potatoes, and related plants. These green worms are 3 to 4 inches long and can defoliate young plants. Mature tomato hornworms can be distinguished by eight L-shaped, white markings along each side of the body and a bluish-black horn near the rear end of the insect. Tobacco hornworms are decorated with diagonal white bars and have a red horn. The white cocoons of a parasite are usually attached to the worm. Pupae of both species are mahogany brown and are found in the soil. In both species, adults are large, gray moths with mottled front wings. Hind wings are lighter. Two thin, zigzag lines run across the midsection of each hind wing of tomato hornworm moths. There is a dark area between these somewhat obscure lines on the wings of tobacco hornworm moths. On both species, five or six yellowish-orange spots can be found along each side of the body. Moths of both species have a wingspread of 4 to 5 inches and fly mainly around dusk. Females lay eggs individually on plants. Eggs are spherical and greenish-white. This insect overwinters as a pupa. In North Carolina, there are two generations a year.

True Armyworm

This caterpillar is sometimes present in very high numbers. Armyworm epidemics can result in the destruction of large areas of vegetation. This pest attacks grasses, corn, and some legumes. Damage usually starts at the edge of a field. Larvae feed at night and may move in hordes. Armyworms are capable of consuming corn plants up to 8 inches tall. This insect stops feeding and overwinters as a partially grown larva. It resumes feeding in the spring. Armyworms are dark greenish-brown worms up to 2 inches long with white stripes down the sides and back. The insect pupates just below the surface of the soil.

Yellowstriped Armyworm

This caterpillar is a daytime feeder. It is capable of doing significant damage to young tomato plantings, pepper fruit, and, occasionally in August, to sweet potatoes. Its presence is sporadic, however. Overwintering as pupae in the soil, yellowstriped armyworms emerge as moths in the spring. Adults are brown, black, and white moths with a 1-1/2 inch wingspread. The moth's forewings are marked with a diagonal band that runs from the front to the rear of the wing and a smoky white stripe along the outside edge of the wing. Hind wings are white with a dark edge. Eggs, covered with scales from the female's body, are laid in clusters on foliage, trees, and buildings. Larvae are dark green with a yellowish-orange stripe along each side and black spots on their abdominal segments. In North Carolina there are several generations a year.

Beetles

Adult beetles are usually hard-bodied insects with thick forewings. The young are grubs, borers, or wireworms. Often adults feed on different host plants than do larvae, although both stages may be destructive to vegetables.

Asparagus Beetle

There are two beetle species that feed on asparagus -- the asparagus beetle and the spotted asparagus beetle. The spotted asparagus beetle, which is reddish-orange and black, is more destructive in northern asparagus production areas. Asparagus beetles are more troublesome in North Carolina. The asparagus beetle is metallic blue with six yellow areas on the wing covers. Beetles are about 1/4 inch long and have a narrow, red head and thorax. This pest overwinters in protected areas and first appears each year in early April along the edges of fields. Adults gnaw tender asparagus buds and lay eggs on developing spears. Eggs are very dark, bulletlike, and laid in rows. Processing plants sometimes reject otherwise edible spears because eggs have been laid on them. Eggs hatch within a week of the time they were laid. Sluggish, humpbacked, slate-colored larvae with black heads feed and grow on asparagus ferns for about 10 days. The pupal stage is passed on the soil. A week or so after pupation, adults emerge and the cycle is repeated. There may be as many as five generations in a year. Asparagus is the only vegetable this insect attacks.

Bean Leaf Beetle

Adult bean leaf beetles range in color from red to yellow. The insect's markings may also vary, but bean leaf beetles generally have a dark triangular mark on the front of the wing covers, six black spots in the center of the back and a black edge around the outside of the wing covers. This insect is about 1/4 inch long and is long-lived. Adults will drop from foliage when disturbed. Bean leaf beetles feed on foliage, making round, regular holes. This pest also attacks the stems of young plants at or slightly below ground level. Females lay eggs in the soil near the base of plants. From the eggs hatch slender, white larvae that feed on the roots of bean plants. Bean leaf beetles spend the winter as adults in trash near bean fields. There is one generation, possibly two, per year. Beans, peas, cowpeas, and soybeans are common host plants; however, this pest will also feed on corn, some clovers, and many weeds.

Blister Beetle

Several species of blister beetle feed on vegetables. The black, striped, and margined blister beetles are most commonly seen in North Carolina. Blister beetles are slender, rather soft insects with a narrow thorax. The tip of the abdomen is exposed beyond the wing covers. Adults are black or gray and sometimes have narrow, yellow or gray stripes or edges on the wings. Adult beetles are ravenous feeders and are capable of destroying plants. The winter is passed as larvae in the soil. Larvae are about 1/3 inch long and yellow. Blister beetle larvae are beneficial in that they feed on grasshopper eggs. The pupal stage also is spent in the soil. Adults emerge from the soil in midsummer and feed in groups for about five weeks. The beetle's body contains an oil called cantharidin that causes blisters if the insect is crushed against tender skin. Yellow eggs are laid in holes in the soil in clusters of 100 or more. It appears there is one generation per year. Blister beetles will attack most types of vegetables but seem to prefer potatoes and tomatoes.

Colorado Potato Beetle

This insect is perhaps best known as the common yellow- and black-striped potato bug. This pest is, however, a beetle and not a true bug. Both adults and larvae feed on the foliage of potatoes. While potatoes are preferred, this pest also attacks tomatoes, eggplant, peppers, and horse nettle. Adults are about 3/8 inch long and 1/4 inch wide and very convex in shape. Black and yellow stripes run lengthwise along the insect's back. Females lay clusters of 20 or more yellowish-organe eggs on the underside of leaves. A single female beetle can lay over 500 eggs over the course of her four-week life. From the eggs come red, hump-backed, soft-bodied larvae decorated with two rows of black spots along each side of the body. Larvae begin chewing on leaves immediately after hatching. Larvae also feed on the fruit of tomatoes and eggplant. In two or three weeks larvae grow to a length of 1/2 inch, then enter the soil to pupate. Seven days later adult beetles emerge from the soil, feed for a few days, mate, and lay more eggs. This insect overwinters as an adult in the soil. There are at least two generations per year.

Cowpea Curculio

This insect most commonly attacks blackeyed and crowder peas. Adults are black, humpbacked snout beetles about 1/4 inch long. The adult female chews a hole in a pea pod and inserts an egg into the developing seed. This small puncture is difficult to see, and damage may go unnoticed until the crop is harvested. Eggs hatch into small, white, legless grubs with yellowish-brown heads. The grubs destroy the peas in a pod. There is at least one generation per year. Hot, dry weather appears to retard development of this pest. Adults overwinter in refuse around fields. Damage may be avoided by alternating from year to year the site where peas are planted.

Flea Beetle

The many different species of flea beetle attack a variety of vegetables. Species that attack potatoes, tomatoes, and eggplant are the most troublesome, but flea beetles also damage corn and sweet potatoes. Flea beetles are so named because of their enlarged hind legs and jumping ability. Adults are 1/16 to 1/18 inch long and usually black with brown legs and antennae. Eggs are laid in the soil at the base of plants. From the eggs hatch cylindrical, brown-headed, white larvae that are about 1/5 inch long when full grown. Larvae commonly feed on roots, often riddling them with tunnels or eating off rootlets. The pupal stage is spent in the soil. These insects overwinter as adults in trash around field borders and in ditch banks. There are three or more generations per year. Round holes chewed in leaves are the most obvious damage caused by flea beetles. On small plants, this "buckshot" damage can result in plant death. On larger plants these feeding sites provide a good entrance for several blights and wilts.

Japanese Beetle

These beetles are metallic green or greenish-bronze, 1/2 inch long with red wing covers, and are decorated with white spots near the tip of the abdomen. They commonly are found in June and July on fruit, deciduous trees, and vegetables. Japanese beetles also are frequent and persistent pests of sweet corn and beans. The insect spends the winter in the soil as a white grub about 3/4 inch long. Beetles emerge from the soil in midsummer and on warm, sunny days swarm to plants, where they eat the foliage, flowers, and fruit. Females beetles then return to grassy areas to lay their white, spherical eggs in the soil. Grubs feed on decaying vegetation and grass roots. Pupation occurs in the soil. There is only one generation each year.

Mexican Bean Beetle

The brown Mexican bean beetle is decorated with 16 black spots arranged in three rows across its back. Beetles are 1/3 inch long, convex, and resemble lady beetles. Adults overwinter on the ground among leaves and trash near fields where beans were grown. When warm weather arrives in the spring, they leave their overwintering sites and feed on beans for a week or two. Females lay lemon-colored eggs in groups of 25 or more on the underside of leaves. Eggs hatch about 10 days after being laid and yellow larvae with six rows of black-tipped, branched spines on their backs appear. Larvae, which are 1/3 inch long when full grown, feed for two to five weeks, then enter the pupal stage. The yellow pupa is attached to a leaf. Traces of the last larval skin can usually be found where the pupa is attached to the leaf. There are three or four generations per year. Both larvae and adults feed on leaves, usually on the underside. Damaged leaves have a skeletonized or lace-like appearance. Sometimes stems and pods are damaged. The insect attacks all kinds of garden beans, cowpeas, and soybeans.

Spotted Cucumber Beetles

(Also called the Southern Corn Rootworm)

In its adult form, this insect feeds on over 200 different plants. It may be found on beans, cucurbits, corn, potatoes, asparaugs, cabbage, peas, beets, tomatoes, and turnips. It feeds on foliage and new shoots, leaving small holes in foliage. It also gnaws holes in fruit. This insect overwinters as a 1/4 inch long, yellowish-green beetle decorated with 12 black spots. The beetle's head and antennae are black. Females deposit eggs at the base of grass and corn plants. From the eggs hatch yellowish-white, brown-headed larvae that are up to 3/4 inch long when full grown. These larvae, called corn rootworms, tunnel in the roots of plants. This tunneling action can result in severe stunting of corn plants and sometimes kills plants. There appears to be two generations per year in North Carolina.

Striped Cucumber Beetle

These 1/5-inch long beetles are yellow and are decorated with three wide black stripes. Striped cucumber beetles damage plants by feeding on leaves, stems, and fruit. They also carry the organisms that cause bacterial wilt of cucurbits and cucumber mosaic. Adults lay yellow eggs at the base of plants. Larvae, which are white and 1/3 inch long, feed on the underground parts of plants or on fruit that touches the soil. There are at least two generations per year. In addition to cucurbits, striped cucumber beetles feed on beans, peas, and corn. The most severe damage is caused to small plants.

Vegetable Weevil

Larvae and adults of this insect feed on foliage and exposed roots of potatoes, turnips, turnip greens, kale, and mustard greens. Late fall and early spring crops are most severely damaged. Adults are gray snout beetles 1/3 to 1/2 inch long. Two white markings on the rear half of the wing covers form a V shape. Eggs laid in the crowns of plants procude green, slug-like larvae. These grubs are about 1/2 inch long when full grown. This pest goes into a resting stage from June to September.

Wireworms

These beetles do the most severe damage to root crops such as Irish and sweet potatoes, although they injure other vegetables as well. There are many different species of wireworms. Adults are hard-shelled, dull colored beetles, ranging from 1/2 to 1-1/2 inches in length. Beetles are tapered toward both ends and appear streamlined. Adults are also known as click beetles because they snap and flip over when turned on their backs. They have a loose, flexible joint just ahead of the wings. Females lay eggs in the soil around the roots of grass plants. The eggs produce yellow to reddish-brown, tough-bodied larvae that are commonly called wireworms. Larvae range in size from 1/2 to 2 inches when full grown, and most are cylindrical and slender. Some wireworms are almost flat. Larvae feed on underground parts of plants. The pupal stage is spent in the soil. It takes over a year to complete the life cycle of a wireworm. Wireworm damage is most severe on land not previously planted in row crops.

White Grubs

There are several species of these pests. Adults are hard-shelled, light brown to almost black beetles from 3/4 to 1 inch long. These insects are sometimes called May beetles and June beetles. They commonly feed at night on the foliage of trees and hide in the grass and lay eggs during the day. The spherical, pearly white eggs produce white C-shaped grubs with brown heads. Grubs feed on grass roots and other crops. The pupal stage is spent in the soil. Among the common white grubs are the larvae of the green June beetle. Larvae feed mainly on organic matter in the soil. Grubs uproot young plants as they move about in and on the soil. Vegetables should not be planted in soil that was in sod the previous year until the soil has been treated to control white grubs as some grubs live two to three years.

Whitefringed Beetle

Among the many vegetables attacked by whitefringed beetles are Irish potatoes, sweet potatoes, beans, and cabbage. Adults, which emerge in June and July, are dark gray beetles about 1/2 inch long, with a white margin or fringe on their sides. White, oval eggs are laid in a gelatinous mass on objects on or near the ground. Grubs are shite, legless, and 1/2 inch long when full grown. Grubs feed on the underground parts of many kinds of plants. The pupal stage is spent in the soil, while the insect overwinters in the grub stage. There is one generation per year.

Sap-Feeding Insects

Some insects damage vegetables by sucking plant juices from leaves, stems, or roots. The true bugs, aphids, whiteflies, and leafhoppers, all have beak-like mouthparts that are used to suck sap from plants. Some of these insects also produce toxic saliva, which they inject into plants. The best known example of plant injury caused by saliva injection is a condition called hopperburn caused by the potato leafhopper on Irish potatoes. Many of these insects also transmit plant diseases. The green peach aphid, for example, is known to transmit potato leafroll virus, while the melon aphid infects squash and watermelon mosaic virus.

Harlequin Bug

These bugs feed on cabbage and related crops and can cause severe damage. Harlequin bugs also feed on beans, asparagus, okra, and tomatoes. The insect damages a plant by extracting juices from it. Adults and nymphs have similar habits. Adults are flat, shield-shaped bugs about 3/8 inch long. They are red or organe with black markings that give the appearance of a mask. Eggs resemble kegs and are laid on end in groups. Each egg has a black band at the top and bottom. Nymphs, which grow through five developmental stages, resemble adults but are smaller and wingless. There are two or more generations of this insect per year. Adults overwinter in any protected area.

Eggplant Lace Bug

Adult eggplant lace bugs are small, flat insects about 1/8 inch long. They are somewhat rectangularly shaped when viewed from above. The wings are net or lace-like. The head is covered with a hood-like structure. Females lay eggs on the underside of leaves. Nymphs are darker than the adults, wingless, and usually covered with spines. Both nymphs and adults inject saliva and suck juices from eggplant leaves. The insect also excretes a brown, varnish-like material.

Squash Bug

This insect attacks only cucurbits. It prefers squash and pumpkins. Adults and nymphs injure plants by sucking sap from them. Damage usually can be detected by the occasional drooping of a leaf. Adults are about 5/8 inch long, brownish-black or gray, and flat across the back. This insect overwinters as an adult and mates in the spring. Reddish-brown eggs are laid on leaves in rows that come together at an angle. Each cluster contains 15 or more eggs, which produce tiny, light gray, wingless nymphs. There is one generation each year. Destruction of crop residue as soon as the crop is harvested helps to control these insects.

Tarnished Plant Bug

Among the many different vegetables this insect attacks are asparagus, Irish potatoes, chard, celery, and beans. A small spot surrounded by a yellow area is evidence a tarnished plant bug has been feeding on a bean seed. Blossoms may drop from a plant as a result of tarnished plant bugs feeding on them. This insect also feeds on the terminals of potatoes, causing leaves near the top of the plant to wilt. Tarnished plant bugs also transmit disease. Adults are small, flat bugs about 1/4 inch long. These somewhat oval insects are mottled brown with irregular splotches of white, yellow, reddish-brown, and black. Eggs are usually inserted into plant tissues. The nymphs resemble adults but are smaller and wingless. There appear to be four or five generations per year in North Carolina. This insect overwinters as an adult. Two other true bugs -- stink bugs and leaffotted bugs -- cause similar injury, especially on beans and southern peas. Damage inflicted by these two bugs on southern peas and butter beans occasionally is serious.

Aphids

Aphids, or plant lice, feed on most vegetables. These insects cause the greatest damage when they suck juices from and inject saliva into plants. Many aphid species transmit viruses that cause diseases. Adults are soft-bodied, pear-shaped, and may or may not have wings. Two cornicles, or "exhaust pipes," extend from the hind end of most aphids. Aphids may be green, pink, yellow, or black. Nymphs resembe adults but are smaller and always wingless. These pests usually feed in clusters.

Potato Leafhopper

This insect feeds on many different host plants including beans and Irish potatoes. Saliva injected by this pest into Irish potato plants causes a deadening and upcurling of the tissues known as hopperburn. Sap feeding on beans causes leaves to be stunted, crinkles, and curled downward. Adults are pale green, wedge-shaped, and about 1/8 inch long. Eggs inserted into plant tissues produce green nymphs that resemble adults but are smaller and wingless. Adults and nymphs suck plant juices. Potato leafhoppers are a problem primarily in western North Carolina. At least three generations of this pest occur each year. The potato leafhopper is one of several leafhopper species found on vegetables.

Whitefly

Whiteflies feed on a wide variety of vegetables. This insect can be found in the field and the greenhouse. Host plants include beans, tomatoes, eggplant, and cucumber. Adults are very small sucking insects with two pairs of broadly rounded wings. The wings and body are covered with a snow white, waxy powder. The insects look like tiny moths and may fly up in a cloud when disturbed. Eggs, which are almost microscopic, are laid on the underside of leaves. Young nymphs are small, flat, and hard to see. All stages are found on the underside of leaves. Leaves may become discolored and fall from a plant on which whiteflies are feeding. Plants on which this insect feeds may also be stunted. Whiteflies secrete honeydew on plants, which allows unsightly black sooty mold to grow.

Flies

True flies are a diverse group. Many species attack humans and animals and can spread diseases. Some flies are beneficial. They feed on decaying matter and prey on or parasitize other insects. Others are plant pests, their maggots or larvae feeding on various vegetables.

Cabbage Maggot

This insect prefers cabbage, cauliflower, broccoli, and related crops. It also attacks beets, radishes, turnips, celery, and other vegetables. The cabbage maggot does most of its damage in the mountain regions of North Carolina. The adult is a gray fly with two wings. It is smaller than a house fly but has proportionately longer legs. Eggs are white and are laid on the soil close to young plants. The eggs hatch into white, wedge-shaped maggots that are about 1/4 inch long when full grown. Maggots feed on roots, either on the surface or by tunneling through them. Fleshy parts of radishes or turnips will show brown streaks where tunneling has occurred. Cabbage maggots overwinter in the pupal stage, which is spent in the soil. There appear to be three generations per year of this pest.

Pepper Maggot

This pest prefers peppers but also attacks eggplant. It is believed that its natural food is horsenettle. Adults are yellow striped flies about 1/4 inch long with dark bars on the wings. Females deposit eggs under the skin of peppers. Maggots are white, legless, and about 1/2 inch long when full grown. Maggots eat the core of the pepper, causing it to decay or drop from the plant. The pupal stage, in which the insect overwinters, is spent buried 2 to 4 inches in the soil. Adult flies appear in late June. There is one generation each year.

Seedcorn Maggot

This insect attacks the sprouting seeds of many different vegetables. Damage may be done to seed pieces of Irish potatoes; seedlings of corn, beans, peas, and cucumbers; or stems of other vegetables. The most serious infestations occur in the spring during cool, wet weather and in soils high in organic matter. Adults are grayish-brown flies about 1/5 inch long. Eggs, from which hatch cream-colored, wedge-shaped maggots, are deposited in the soil close to plants. Maggots are 1/4 inch long when full grown, legless, and have chewing mouthparts at the narrow end of the body. It is as a maggot that this insect is destructive. This pest overwinters in the soil in the pupal stage. The pupa is enclosed in a brown, capsule-like case. There are three generations of this pest each year. Destruction of crop refuse and shallow planting in warm soils will enhance plant establishment.

Vegetable Leafminer

This insect's name derives from the maggot's habit of tunneling or mining in leaves -- feeding between the upper and lower leaf surfaces. Damage appears as winding white trails or broad white spots. Leafminers attack many vegetables but do the most damage to cucumbers, squash, tomatoes, and leafy vegetables such as cabbage, kale, and collards. The leaves of a plant that is attacked by vegetable leafminers are weakened, while the mines serve as sites for disease and decay. Adults are gray to shiny black flies less than 1/8 inch long. Small, white eggs deposited in leaves produce white or yellow maggots that tunnel through the leaves. The tunnel is narrow and winding at first. It becomes larger as the maggot grows, finally forming a blotch. The pupal stage is spent in the soil, and it is in this stage that this pest overwinters. There are several generations each year in North Carolina.

Other Insect Pests

Moths and butterflies, beetles, sap-feeding insects, and flies are not the only insects capable of damaging vegetables. Grasshoppers, mole crickets, and thrips also attack vegetables.

Grasshoppers

Many species of grasshopper damage vegetables. Usually these pests migrate from dried up vegetation to more succulent vegetables. Adults and nymphs cause damage by feeding on foliage. Adults have front wings that are longer than the body and are held roof-like over the insect. Hind wings are softer and are folded fanlike beneath the forewings when the insect is at rest. The hind legs are long and adapted for jumping. Size varies according to species. Nymphs resemble adults in habits and appearance but are smaller and wingless. Most species overwinter as eggs, which are laid in packets in the soil.

Mole Cricket

This insect burrows in the soil, causing major damage by uprooting young plants. Mole crickets are capable of severely damaging the roots and tubers of Irish and sweet potatoes. Damage to foliage may also occur. Adults are velvety brown and about 1-1/2 inches long. This insect has short forewings and long, membranous hind wings. The front legs, rake-like and developed for digging, somewhat resemble the forepaws of a mole. Hind legs are enlarged. Eggs are laid in an underground chamber. Nymphs are small, wingless versions of adults. Nymphs and adults overwinter. There is one generation each year in North Carolina.

Thrips

Several species of thrips damage vegetables. The most severe damage usually occurs in hot, dry years. Damage appears as white flecks or streaks on leaves. Adults are small slender insects about 1/20 inch long. They vary in color from light to dark brown. Wings are narrow and fringed, giving them a feathery appearance. The males of some species are wingless. Eggs are thrust into plant tissues. Nymphs are active, light-colored, wingless insects. The mouthparts of adults and nymphs are similar and unusual; they are designed to rasp plant tissues then suck the juices. The last nymphal stage is spent in the soil. Adults and nymphs pass the winter on plant tissue. There may be as many as five generations each year in North Carolina.

Noninsect Vegetable Pests

Spider mites and slugs, although not insects, are capable of inflicting severe damage on vegetables.

Spider Mites or Red Spiders

Mites are closely related to insects. Many species of this pest attack vegetables. Beans and tomatoes may be severely damaged, while crops such as eggplant, cucumber, and celery are also susceptible. These pests appear to cause more severe damage during hot, dry years. Adults are usually red, yellow, or green, about 1/ 50 inch long, and have four pairs of legs. The body is oval. Adults lay eggs on plants. The eggs hatch into young mites that resemble adults but are smaller. Adults and nymphs suck plant juices. Plants attacked by mites appear sickly and white-speckled. Affected leaves curl, turn brown, and drop from the plant prematurely. When an infestation is severe, fine silk webs may entangle an entire plant, and moving spider mites can easily be seen in the webbing. Many generations may occur each year.

Slugs

Slugs are similar to snails but lack the snail's hard, protective shell. Six species of slugs attack vegetables and ornamental plants in North Carolina. Slugs feed on mold, decaying organic matter, and live plant tissue including foliage, flowers, or fruit. Slugs may chew jagged edges along leaves, shred leaves, or eat completely through leaves or stems. Damage is most severe in damp areas or during extended rainy periods. Slugs vary in size from less than 1/2 inch to more than 4 inches long and range in color from ash-gray or yellow-gray to black. Some are mottled. Young slugs resemble adults but are smaller and lighter in color. Eggs, gelatinous and water appearing, are laid in clusters of about 25 on the soil in concealed, moist areas. Slugs are active at night, leaving silvery slime trails that can be seen the next morning.