Science, Tech, Math › Animals & Nature 12 Worst Vegetable Garden Pests Take Back Your Garden Without Using Chemicals Share Flipboard Email Print Hero Images/Getty Images Animals & Nature Insects Basics Behavior & Communication Ants. Bees, & Wasps Beetles Butterflies & Moths Spiders Ticks & Mites True Bugs, Aphids, Cicadas, and Hoppers Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Marine Life Forestry Dinosaurs Evolution View More By Debbie Hadley Entomology Expert B.A., Political Science, Rutgers University Debbie Hadley is a science educator with 25 years of experience who has written on science topics for over a decade. our editorial process Debbie Hadley Updated May 24, 2019 There's nothing more discouraging to a gardener than having a whole crop of your favorite vegetable wiped out by pests. Once those hungry insects have found your garden, they're likely to come back year after year. But don't give up hope. All is not lost. You can take your garden back from insect pests, and you don't even need to resort to using chemical pesticides. These 12 garden pests cause the most damage in home vegetable gardens. Learn to recognize each pest, as well as the signs and symptoms of an infestation, and how to control each pest organically. 01 of 12 Colorado Potato Beetle USDAgov/Flickr/CC BY 2.0 Colorado potato beetles were once a pest of the west, but they migrated east by feeding on potato crops in the 1800s. Description Colorado potato beetles are dome-shaped and measure just 3/8-inch long. Adults are yellow with 10 narrow black lines running longitudinally along their elytra. Larvae look similar to other beetle larvae - soft-bodied, with two rows of black dots along the sides. Colorado potato beetle larvae are brick red with black heads in the earliest instars. Eggs are yellow-orange and laid in clusters on the undersides of leaves. Life Cycle Adult Colorado potato beetles overwinter in the garden soil, emerging in spring. Females lay eggs on the foliage of early crops of solanaceous plants, especially potatoes. First generation larvae feed for 10-30 days, dependant on temperatures. Fourth instar larvae drop to the ground and pupate in the soil, emerging as adults within 2 weeks. These adults will feed, mate, and reproduce as well. The second generation of adults feeds until fall when they burrow into the soil for winter. Crops Damaged Potatoes, tomatoes, peppers, eggplant. Both adults and larvae feed on foliage, stems, flowers, buds, and fruit of affected crops. Signs and Symptoms If left unchecked, Colorado potato beetles can completely defoliate potato plants and other hosts. If you see signs of defoliation, check for beetle larvae. Late instar larvae cause the most damage to plants. Also, look at the undersides of leaves for clusters of yellow eggs. Control Measures Crush egg masses by hand.Handpick adults and larvae, dropping them in a can of soapy water to destroy them.Use a barrier, such as cheesecloth, on young seedlings to prevent beetle damage.Plant varieties that mature early to avoid damage by second generation beetles.Attract beneficial insects, especially ladybugs and stink bugs, to prey on beetle eggs and larvae.Apply Bacillus thuringiensis var. tenebrionis when larvae are young (first and second instars).Weed the garden before spring adults emerge to eliminate food sources. Colorado potato beetles will feed on ground-cherry, jimsonweed, thistle, mullein, and horse nettle when potatoes or other garden crops are absent. 02 of 12 Cabbage Looper Whitney Cranshaw, Colorado State University, Bugwood.org The cabbage looper is primarily a pest of brassica crops, but will sometimes expand its smorgasbord to include everything from cantaloupe to tomatoes. Description Cabbage looper larvae move like inchworms, in a looping motion, because they lack legs in the middle portion of their bodies. Older caterpillars are light green, usually with a white stripe down each side. Younger larvae tend to be paler. Adult moths are grayish brown, but can be recognized by a distinct silvery mark on each forewing shaped like a figure eight. Cabbage looper eggs are very pale green to white, and found on the upper surfaces of leaves. Life Cycle Adult cabbage looper moths migrate to northern areas in spring or summer. Moths deposit eggs on host plants, usually singly. The eggs hatch in 2-10 days, dependent on temperature. Early instar larvae feed on the lower surfaces of leaves, while larger caterpillars do more conspicuous damage. Mature larvae pupate on the undersides of foliage or in the soil. The adult emerges in 1-2 weeks. Multiple generations occur during the growing season. Crops Damaged Mainly brassicas: cabbage, cauliflower, broccoli, kale, turnips, mustard, and others. Sometimes damages other crops, including tomatoes, peppers, eggplant, potatoes, watermelons, cucumbers, melons, squash, cantaloupe, peas, beans, and others. Signs and Symptoms Ragged holes in leaves, mainly between the veins. Dark green frass. When looper numbers are high, damage may be enough to stunt plant growth or prevent head formation in cabbage and similar crops. Control Measures Keep the garden free of weeds, especially those preferred by cabbage loopers – wild mustard, peppergrass, and wild cabbage.Monitor susceptible plants for cabbage looper eggs and crush them before they hatch.Check the undersides of leaves for young looper larvae. Hand pick and destroy them by dropping the caterpillars in soapy water.Use floating row covers as a barrier to moths. Be sure to anchor all sides of the row covers.Collect diseased caterpillars and make your own cabbage looper remedy. Cabbage looper larvae are susceptible to a virus that kills them. Infected caterpillars will look yellow or white, and swollen. Blend these sick caterpillars with water and spray it on plants to infect other larvae.Apply Bacillus thuringensis when larvae are young. 03 of 12 Bronzed Cutworm and Other Cutworms Bronzed cutworm. Whitney Cranshaw, Colorado State University, Bugwood.org Cutworms are so named for their annoying habit of cutting down seedlings, usually right at or near the soil surface. Description: Cutworms are the caterpillars of various moths in the family Noctuidae. They vary in color and markings according to species, but a common behavior of cutworms is their tendency to curl into a letter C shape when disturbed. The adult moths are medium-sized, somewhat drab night fliers. The moths pollinate flowers, and don't do any direct harm to garden crops. Life cycle: Cutworms generally overwinter as larvae, so they're ready to feed as soon as temperatures warm and the first garden plants are installed. By late spring, the caterpillars have tunneled into the soil to pupate. Adult moths emerge in summer, when they mate and lay eggs. A singe female may lay hundreds of eggs, often on weeds in the garden. The new generation of larvae feed until temperatures drop low enough to send them into hibernation for winter. Crops damaged: Tomatoes, peppers, eggplant, potatoes, corn, peas, beans, celery, carrots, lettuce, and many other common garden crops. Different cutworm species prefer different host plants. Signs and symptoms: Young garden plants severed at or near the soil surface, usually overnight. Most cutworm problems occur in spring when plants are tender and small. Some cutworms feed on foliage, buds, or fruit, and others feed on the roots. Control measures: Turn and till your garden soil before planting in the spring to disturb overwintering cutworms.Look for signs of cutworm activity late in the day or in the early evening, when the caterpillars are most active. Damaged or severed stems or the presence of frass may indicate a cutworm problem.If you find evidence of cutworms, try to find them in the soil around the affected plant. Collect and destroy any cutworms you find hiding in the soil.Install collars around seedlings to act as a barrier to cutworms. Push one end into the soil a few inches, and allow the other end to extend above the soil surface. Cardboard toilet paper rolls can work well for this.Plant a perimeter of sunflowers around your garden to act as a trap crop for cutworms. Monitor the sunflowers for cutworms and destroy them as you find them.Remove any plant debris and pull weeds to minimize places for small cutworms to shelter.At season's end, turn and till your garden soil again. 04 of 12 Bean Leaf Beetle Bean leaf beetle. Adam Sisson, Iowa State University, Bugwood.org Multiple generations of bean leaf beetles may attack snap beans and other legumes in the home garden. Description: Adult bean leaf beetles come in several colors, from yellow-green to red, and their markings can vary as well. Regardless, all bean leaf beetles have a characteristic black triangle mark at the front of the elytra, just behind the pronotum. Generally only the adult beetles will be visible, as all other forms live in the soil. The eggs are oval and orange-red in color. Larvae are white with black ends. The pupae are ghostly white copies of the adults. Life cycle: Adult bean leaf beetles overwinter in leaf litter or in the soil, usually preferring wooded areas for shelter. As soon as temperatures begin to warm up in the spring, the first adults emerge to feed and mate. Females lay about a dozen eggs at a time in the soil under legume hosts. After several weeks of feeding on the roots, larvae pupate in the soil. Adults emerge to repeat the cycle. In southern areas, bean leaf beetles can produce multiple generations within a growing season. Crops damaged: Snap beans, soybeans, and other legumes. Adults feed on both the foliage and pods, while larvae feed on the roots. Signs and symptoms: Round holes in foliage, within the leaf margins. Stunted plant growth due to larvae feeding on roots. Cosmetic damage to pods late in season. Control measures: If you notice feeding damage, hand pick adult beetles and drop them in soapy water to destroy them. Beetles are most active in the afternoon, so monitor your plants at this time.Young seedlings are most susceptible to bean leaf beetle damage. Be vigilant when plants are young.If you've had problems with bean leaf beetles in past growing years, consider planting snap beans later in the season to avoid early emerging adults in spring. 05 of 12 Aphids Aphids. Getty Images/Corbis Documentary/Paul Starosta In moderate numbers, aphids don't do as much harm to garden plants as one might think. But once you start seeing sooty mold or curled leaves, it's time to act. Description: Aphids are tiny true bugs with piercing, sucking mouthparts designed to suck the juices from plants. They are usually wingless and pear-shaped. You can recognize aphids easily by the pair of cornicles projecting from their hind ends – two tiny "tailpipes" that other soft-bodied insects lack. Aphids vary in color according to species and host plants. Life cycle: The aphid life cycle is unusual in that females can birth live young, and do so without mating. Aphids overwinter as eggs, from which wingless females hatch in spring. These females give rise quickly to the next generation of Amazon aphids, and the cycle continues throughout the growing season. As fall approaches, aphids begin producing some males with which they mate. Only then do the female aphids rely on traditional reproductive methods, laying eggs that will carry her genes through the winter months. Crops damaged: Nearly all garden crop. In particular, aphids prefer beans, peas, melons, cucumbers, pumpkins, squash, tomatoes, potatoes, and cabbage. Aphids can also transmit diseases to many of these crops. Signs and symptoms: Curled or yellowed leaves. Stunted growth. Blackening on foliage (sooty mold). Control measures: Use a strong spray of water to knock aphids from sturdy plants.Attract beneficial insects to your garden. Most predatory insects will feast on aphids when they are present in high numbers. Avoid using broad spectrum pesticides that will kill beneficials along with pests.Don't over fertilize your plants. When you give your aphid-infested plants a nitrogen boost, you're actually boosting aphid reproduction and creating a bigger problem.Keep the garden free of weeds, and check for infested ornamentals near your vegetable garden that might harbor aphids.When possible, prune any heavily infested shoots from plants and destroy them, aphids and all.Apply neem oil, horticultural soap, or horticultural oil when appropriate. These products work on contact, so repeat applications will be necessary. Be sure to get the undersides of leaves where aphids may be hiding. 06 of 12 Cucumber Beetles Cucumber beetle. Flickr user (CC by SA license) Two kinds of cucumber beetles are poised to eat your seedlings. Worse yet, they transmit bacterial wilt. Description: The striped cucumber beetle, as you might expect, bears three longitudinal stripes down its wings. The spotted cucumber beetle, in contrast, is marked with 12 black spots. Both kinds of cucumber beetle are somewhat oblong in shape with black heads and yellowish bodies. Cucumber beetle larvae are thin white grubs with brown head capsules. Eggs are yellow to orange in color, oval, and found in clusters of up to 50. Life cycle: Adult cucumber beetles overwinter, usually sheltering in woodlands or dense grasses. They emerge in spring, feeding on pollen and other plants until their preferred cucurbit hosts are available. Once garden crops are planted, the adults move onto cucumbers, squash, and other favorite plants to continue feeding. Mated females lay eggs in the soil below; each female can produce up to 500 eggs. When larvae hatch, they feed on plant stems and roots in the soil before pupating. The next generation of adults emerges in mid-summer, and repeats the cycle. Crops damaged: Cucumbers, squash, pumpkins, cantaloupe, gourds, and melons. Occasionally also beans, peas, or corn. Spotted cucumber beetles will feed on a wider range of host plants, including tomatoes, eggplant, and potatoes. Signs and symptoms: Girdled seedlings. Scarring on fruit. Feeding damage to leaves and flowers. Flagging of leaves and eventual vine wilt are signs of bacterial wilt disease, spread by cucumber beetles. Control measures: Promote good root growth by fertilizing crops properly early in the season. Healthy plants will better withstand cucumber beetle infestations.Use barriers to protect young seedlings from adult beetles. Cones, row covers, or cheesecloth will keep cucumber beetles from feasting until plants are large enough to tolerate them.Delay planting cucurbit crops until later in the season.Remove and destroy and wilt-infected plants immediately.Plant resistant varieties, such as Blue Hubbard squash or Gemini cucumbers. 07 of 12 Squash Vine Borer Squash vine borer. NY State IPM Program at Cornell University (CC by SA license) Squash vine borers can wipe out the entire year's harvest of squash, pumpkins, or zucchini. Description: The squash vine borer is a moth. Squash vine borer larvae are cream-colored, with brown heads, and grow to nearly an inch long. Adult moths resemble red wasps, with black dots on their abdomens and greenish forewings. Squash vine borer eggs are tiny, brown, and flat. Life cycle: Squash vine borers overwinter as cocoons in the ground, emerging as adults in late June or early July. Adult moths lay eggs on the stems of host plants, usually just above the soil line. Adults will oviposit eggs through mid-summer. When larvae hatch they immediately penetrate the plant stem, where they feed on plant tissue for up to a month. Final instar larvae move into the soil to pupate and overwinter. In southern areas, two generations of squash vine borers may occur in a season. Crops damaged: Squash, zucchini, pumpkins. Rarely cucumbers and melons. Signs and symptoms: Sudden wilting is a sure sign of vine borers. Larvae feeding in the plant stems disrupt the flow of water and nutrients within the vine. Careful examination of the stem just above the soil line may reveal entrance holes, piles of frass, or visibile larvae. Control measures: Monitor for adult moths using yellow pan traps. Place yellow pans filled with water near vine crops in mid-June, and check them daily for adults vine borers.Use row covers or other barriers over susceptible plants when you begin seeing adult vine borers. Be sure to remove any barriers when plants start flowering to allow pollination by bees.Wrap lower plant stems with foil to prevent adults from laying eggs.Monitor plant stems for holes and frass, signs that a vine borer has entered the vine. If you find a vine borer, use a sharp, clean knife to slit the stem open lengthwise and remove the borer. Mound moist soil around the stem after you've removed any borers to encourage root growth.Remove and destroy any dead vines immediately.Turn or plow garden soil at the season's end, and again in spring before planting, to disturb any overwintering vine borers in the soil. 08 of 12 Squash Bug Squash bug. Getty Images/PhotoLibrary/Dr. Larry Jernigan Squash bugs suck sap from squash, pumpkins, melons, and other cucurbits in the home garden. Description: Like many true bugs, squash bug adults are flat with wings that fold over their backs. The edges of their abdomens have light orange stripes, but otherwise, these pests are black or brown. Newly emerged nymphs are greenish in color with black heads and legs. As they progress through five instars, the young bugs darken to their adult colors. Squash bug eggs, found in clusters on the undersides of foliage, are bronze or yellow. Life cycle: Adult squash bugs overwinter by seeking shelter in leaf litter, garden debris, woodpiles, or other protected places in the yard. When vines begin running in early summer, these adults mate and lay eggs on host plants in the garden. Eggs hatch in about 10 days. Nymphs develop over the course of 4-6 weeks. In late summer, it's common to observe eggs, nymphs, and adults together in the garden, as generations overlap. Crops damaged: Squash and pumpkins. Sometimes gourds, melons, or cucumbers. Both adults and nymphs damage plants by sucking on sap. Signs and symptoms: Yellow spots on foliage of susceptible plants. Wilting or withering vines. Spots or entire vines turning black. Control measures: Hand pick adults and nymphs, dropping them in a can of soapy water to destroy them. Squash bugs flee and hide when disturbed, so this is easier said than done.Use trap boards on cool nights in spring to collect squash bugs. Check under boards in early morning before bugs become active, and destroy any gathered underneath.Monitor plants for eggs, and crush any squash bug eggs present.Remove and destroy vines immediately after harvesting fruit to discourage squash bugs late in the season.Limit places where squash bugs can shelter in the garden. 09 of 12 Flea Beetles Flea beetle. Flickr user Katja Schulz (CC license) Flea beetles are tiny pests that take tiny bites, but collectively they can do some damage to garden plants. Description: With the exception of the larger spinach flea beetles, these pests are tiny, measuring just a few millimeters long. Most species are dark colored, and many have a metallic shine. Flea beetles are so named for their ability to jump when disturbed; they have large hind legs that give them a surprising vertical leap. Life cycle: Adult flea beetles overwinter in leaf litter, garden debris, or other sheltered places. As temperatures begin rising in spring, the adults emerge and locate suitable host plants on which they feed. Some flea beetles will feed on weeds until garden crops are available. In late spring, female flea beetles lay eggs in the soil around the base of host plants. Tiny larvae feed on roots and root hairs for about a month, and then pupate in the soil. Multiple generations of flea beetles may occur in many areas. Crops damaged: Corn, cucumbers, squash, melons, pumpkinds, gourds, eggplant, potatoes, tomatoes, cabbage, lettuce, celery, radishes, peppers, spinach, sweet potatoes, carrots, watermelon, and others depending on flea beetle species. Signs and symptoms: Numerous small holes in plant foliage, giving leaves a buckshot-ridden appearance. Stunted or wilting seedlings. Blemished or pimples root crops. Control measures: Keep the garden free of weeds, especially in early spring when emerging adult flea beetles are looking for food.Plant transplants instead of seeding directly, and the larger the better. Seedlings and small transplants are most susceptible to flea beetle damage.Use barriers – row covers or cheesecloth – on young plants to prevent flea beetles from feeding on them.Delay planting until later in the season, especially after mild winters. Early season flea beetles do the most damage, and will be more abundant if the winter weather wasn't cold enough to kill them.Use yellow sticky traps, available at home and garden centers, to monitor for flea beetles in the garden.Plant an early trap crop – radishes work well – to lure the flea beetles away from your more desired garden vegetables.At season's end, clear the garden of all debris and pull any weeds to minimize overwintering by adult flea beetles. 10 of 12 European Corn Borer European corn borer. Getty Images/Michael Siluk/UIG Though named for its impact on corn, the European corn borer will feed on a huge variety of crops, and has a particular preference for peppers. Description: European corn borer caterpillars are light pink or gray, with brown head capsules and dark dots down each side of their bodies. The yellow pupae are rarely seen, since metamorphosis occurs within the confines of the larval tunnel. The night-flying moths are somewhat nondescript, with grayish brown wings marked by darker lines and yellow areas. Freshly deposited eggs are cream-colored, but age to a deeper beige or tan. Life cycle: Late instar caterpillars overwinter in corn stalks or other garden litter, then pupate in early spring. Adult moths emerge in late May or June. Females deposit eggs in clusters of 15-20. The larvae develop, feeding on the host plant, and pupate about a month later. In all but the most northern areas, at least two generations occur during the growing season. Crops damaged: Primarily corn, snap beans, lima beans, peppers, and potatoes. Less frequently, okra, cabbage, beets, celery, eggplant, tomatoes, and other thick-stemmed herbaceous plants. Signs and symptoms: In corn, European corn borers feed first on the leaves, then move to the tassels and pollen. Older larvae bore into the stalks and ears. In potato plants, borers tend to penetrate the stem, sometimes causing the plant to topple over. For most other crops, the damage is usually restricted to the fruit. Control measures: At season's end, clear the garden of all weed debris and plant stalks large enough to shelter overwintering borers.Destroy all corn stalks after harvest. Don't put corn stalks or ears in compost piles, as this may allow borers to overwinter.Attract beneficial insects, especially lacewings, lady beetles, and predatory or parasitic wasps.Plant hot pepper varieties, which are more resistant to European corn borer than bell peppers.In northern areas where only one generation of corn borer occurs, planting corn later in the season may limit infestations.When European corn borer populations are high in corn and peppers crops, a pesticide spray may be warranted. Consult your local extension office for advice. 11 of 12 Asparagus Beetles Spotted asparagus beetle. Getty Images/PhotoLibrary/Dr. Larry Jernigan Both the common and spotted asparagus beetles feed on asparagus plants, though the common variety does more damage. Description: Both the common and spotted asparagus beetle are oval in shape and measure just 1/4 inch long. Beyond these similarities, they look quite different. The common asparagus beetle is a colorful adult, with blueish-black wing covers with 6 rectangular yellow markings and red margins. In contrast, the spotted asparagus beetle is uniformly orange with 12 black spots on the elytra. In both species, the larvae have light-colored bodies and black head capsules. Eggs in both cases are oval. The spotted asparagus beetle tends to lay its eggs on the ferns, while common asparagus beetles prefer to oviposit on stalks. Life cycle: Asparagus beetles overwinter as adults, seeking shelter in piles of garden debris, under tree bark, or in old asparagus stalks. The common beetles emerge first in spring, followed by the spotted variety. Both feed on the tender shoots of young asparagus, then mate and lay eggs on the host plants. Common asparagus beetle larvae, which hatch in about one week, feed mostly on the ferns. Spotted beetle larvae prefer the berries. Mature larvae burrow in the soil to pupate. In most areas, more than one generation of asparagus beetle occurs per year. Crops damaged: Asparagus. Signs and symptoms: Brown, scarred, or bent asparagus stalks. Defoliation of ferns. Control measures: Hand pick adult beetles when they first appear, and larvae later in the season. Destroy beetles by dropping them in a can of soapy water.Use a soft broom to brush asparagus plants and knock larvae to the ground. The larvae will usually die on the ground before climbing back up the plant.Clean up plant debris and pull weeds at season's end to limit overwintering sites for adults.Crush any asparagus beetle eggs.Avoid using broad spectrum pesticides in your garden, which may kill a parasitic wasp that kills asparagus beetles. Look for these tiny green wasps around your asparagus crop. 12 of 12 Tomato and Tobacco Hornworms Hornworm. Getty Images/Moment Open/©Studio One-One A late instar tomato hornworm can chew a good-sized tomato plant to the ground overnight. Description: Early instar caterpillars range in color from white to yellow. As they molt and grow, tomato hornworm caterpillars turn to green with 8 v-shaped white marks on each side of their bodies. Tobacco hornworms differ slightly, having 7 diagonal white marks down each side instead. Both tomato and tobacco hornworms have a hornlike projection on their last segments – thus the name hornworm. Both pests are the larvae of sphinx moths, fat-bodied moths with small forewings. Eggs are oval and green, and laid singly on leaf surfaces. Life cycle: Both tomato and tobacco hornworms overwinter in the soil as pupae. In spring, adults emerge from the ground to mate and lay eggs. When garden crops are not yet available, the adult moths will lay their eggs on other solanaceous plants, including weeds like jimsonweed, nightshade, and horse nettle. Caterpillars feed on foliage, reaching maturity within 4 weeks. The larvae then drop to the ground and pupate. A second generation of moths in midsummer, just when tomatoes and other nightshade crops are beginning to flower. These second generation caterpillars tend to do the most damage in the garden, before pupating in the soil in fall. Crops damaged: Tomatoes, potatoes, eggplants, and peppers. Caterpillars feed on foliage and sometimes on unripened fruit. Signs and symptoms: Defoliation of host plants, especially near the top of the plants. As caterpillars get larger, defoliation accelerates and entire plants can be devoured quickly. Frass (black or green caterpillar droppings) on lower leaves or on ground under affected plant. Control measures: Hand pick caterpillars and drop them in soapy water to destroy them. This requires a good eye, as hornworm caterpillars are well camouflaged.Turn or till soil at the end of the season to disturb any burrowing caterpillars or pupae.Keep the garden free of solanaceous weeds that provide tomato and tobacco hornworms additional hosts.Apply Bacillus thuringensis when larvae are young.Attract beneficial insects, such as predatory wasps and lady beetles, that feed on eggs and young caterpillars.Braconid wasps parasitize hornworms. If you find a hornworm with white, cylindrical projections on its body, leave it in the garden. These are braconid wasp pupae, and more parasitic wasps will emerge from them and find other hornworms to parasitize.