Managing Above-Ground Pests in the Garden is part three of three in the Garden Bugs series.
Nonchemical methods for managing garden pests that feed on the foliage and fruit of garden vegetables.
- To repel aphids, anchor aluminum foil to the soil for 1 foot around transplants. Slope soil away from plant so rain water and mud do not obscure reflective surface. You may remove foil after plants flower.
- Make a water trap by painting a small, shallow pan bright yellow and filling it with soapy water. Place several pans in the garden and refill them after each rain. Use bright yellow-painted (Rust-Oleum 659 or Safety Yellow) 6- x 8-inch cards or pieces of plywood as sticky traps. Anchor vertically to garden stakes and spray with Tanglefoot or other sticky substance. Replace Tanglefoot weekly.
- Hand remove and destroy aphid colonies on plant leaves.
- Use a strong spray of water from the hose to knock aphids from plants.
- Spray plants with RTU insecticidal soap or horticultural oil (RTU = ready to use). Test tender plants first to ensure they are not burned by the soap or oil solution. Follow all label directions if using a concentrated product.
- Because aphids can transmit plant virus disease, remove and destroy diseased plants to delay spread of virus to healthy plants.
- Plant marigolds near asparagus to repel beetles.
- Destroy and bury plant refuse in the fall to remove overwintering sites.
- Handpick and destroy eggs, larvae, and adults in the morning before they become active.
- Spray asparagus ferns with pyrethrin or rotenone in late summer so fewer beetles will overwinter.
- Cut foliage off at the ground as soon as it begins to die back.
Cabbage Loopers and Cabbageworms
- Cover plants with cheesecloth or floating row cover to prevent egg-laying.
- Handpick. The green worms are much easier to spot on red-leaf varieties.
- Spray plants with Bacillus thuringiensis when worms are still small.
- Remove alternate host weeds, such as wild mustard and shepherd’s purse, from the garden.
- Interplant a hot pepper plant between every two cabbage plants.
Colorado Potato Beetle
- Potato beetles prefer to feed on potato, eggplant, and tomato. Rotate these preferred hosts with other crops in alternate years.
- Interplant nonhost crops, such as beans, with preferred host crops.
- Handpick orange egg masses, reddish brown larvae, and yellow-and-black-striped adults and destroy.
- Place straw mulch around plants as a barrier to beetle colonization of plants in the spring.
Corn Earworm (Tomato Fruitworm)
- With no controls applied, earworms usually damage only the tip of the ear. Cut off the damaged tips and you can eat the rest.
- If possible, avoid planting other vegetables near corn, a favorite food of corn earworm.
- Plant and harvest corn as early in the season as possible to avoid heavy infestations.
- Drop 1⁄4 teaspoon of mineral oil on the silks of each corn ear after the silks have wilted but before they begin to dry; this helps to repel moths and egg-laying.
- Select tight-husked corn varieties for planting. Tight husks inhibit worm movement into the ear.
- Beginning at the flower stage, check upper tomato leaves once a week for small, round, white fruitworm eggs. Spray plants with Bacillus thuringiensis weekly as long as you detect eggs.
- Plant nonbitter cucumber varieties; the bitter compound in cucumber attracts beetles.
- Cover young plants with cheesecloth or floating row covers until just before bloom.
- Interplant cucumber with radishes; radish seems to repel cucumber beetles. Tansy, marigolds, and nasturtiums also
- Eliminate weeds in and around the garden; some weeds are hosts for bacterial wilt disease that is spread by cucumber
- Unless flea beetle populations are heavy, their feeding will not kill plants or reduce yields; control is usually unnecessary.
- Flea beetles are most numerous in the spring; plant susceptible crops like eggplant and radish later in the season.
- Weeds bordering the garden may serve as alternate hosts; removing weeds will reduce flea beetle populations.
False Chinch Bugs
False chinch bugs are weed-feeding insects that may build up in large numbers in arid conditions. They migrate in huge numbers that may overwhelm any control efforts.
- Early-season control of cruciferous weed hosts may help reduce numbers.
- If damage from false chinch bugs reaches unacceptable levels, treatments to field edges will help control this pest.
- False chinch bugs are easily drowned. Heavy watering or use of a strong hose spray will drown many. Trenches or pans of water may be put around plants during periods of insect migration.
- Trap grasshoppers by using a 1 quart container half filled with a 10% molasses and water mixture.
- Grasshopper populations are most damaging in late summer. Use a floating row cover to protect late-season plantings.
- Plow the garden in the fall to expose grasshopper eggs to the weather and insect predators. Be sure to plow fence rows and
garden borders too.
- Avoid planting garden near lawns or in land previously containing lawn.
- Purchase a Japanese beetle pheromone trap to reduce beetle numbers. Locate trap at least 30 feet away from crop plants.
- Protect plants with floating row covers.
- Apply milky spore powder to surrounding lawn or pasture. Milky spore powder is generally available on the Internet.
- Protect plants with cheesecloth or other fine mesh row covering.
- Hang bright yellow (Rust-Oleum 659 or Safety Yellow) 6- x 8-inch boards covered with a thin coat of Tack Trap or Tanglefoot at crop level. When the boards are filled with insects, wash them and repeat.
- Spray plants with insecticidal soap.
- Because leafhoppers can transmit virus diseases, remove diseased plants to delay spread to healthy plants.
Mexican Bean Beetles
- Handpick and destroy egg masses and beetles in early morning before they become active.
- Interplant nonhost crops like potatoes among bean plants to disrupt egg-laying.
- Use soybeans as a trap cover. Bean beetles prefer soybeans planted nearby over snap or lima beans.
- Spray plants with insecticidal soap.
- Keep the foliage wet to deter mites, which don’t like moist conditions; however, keeping the foliage wet can also encourage
- Cover plants with an old blanket to create a cool, moist environment that deters mites.
- Spray plants with water or insecticidal soap; then cover infested plants for 3 days and follow with a second soap spray.
- Remove and destroy clusters of oval, orange-brown squash bug eggs.
- Remove and destroy vines and unused fruit after harvest to eliminate overwintering sites.
- Place shingles or boards near squash or pumpkin plants in spring or early summer to attract squash bugs; then collect and destroy adult bugs under the boards each morning.
- Plant nasturtiums and marigolds near squash plants to deter squash bugs.
Squash Vine Borers
- Cover plants with fine mesh cloth or row cover until female flowers appear. Female flowers have a bulge between flower and stem that is absent in male flowers.
- Plant squash varieties with long vines. These varieties of squash may continue to grow despite borer damage.
- Plant in late summer or fall to avoid heavy vine borer infestations.
- Cut open borer entry holes in the stem with a knife; then remove the worm and pack moist earth around the stem.
- Handpick worms from plants; check plants in the evening with a flashlight.
- Spray Bacillus thuringiensis when the worms are still small.
- Plant dill next to tomatoes as a preferred trap crop; hand-pick worms off the dill.
- Do not destroy hornworms with small, white cocoons attached to their body. These are parasite cocoons from which small, parasitic wasps (beneficial) will emerge.
- Turn the soil in the fall to expose hornworm pupae to weather and predators.
Weevils (Bean Weevil or Cowpea Curculio)
- Plant resistant, thick-hulled southern pea varieties like AUbe or Freeze-Green.
- Plant beans as early as possible, and turn plants under after harvest.
- Pick shell beans when somewhat green; then blanch before freezing; this will kill weevil eggs and larvae which are seldom seen in the frozen beans.
- Before storing, heat beans in a 175°F oven for an hour. Cool beans; then bag and freeze them for a week to kill any weevil larvae or eggs. After this, store beans at room temperature.
- Whiteflies are rarely a problem in outdoor gardens. Make sure purchased transplants are not infested with whiteflies or other insects.
- Hang bright yellow (Rust-Oleum 659 or Safety Yellow) 6- x 8-inch boards, covered with a thin coat of mineral oil, Tack Trap, or Tanglefoot at crop level.
- Spray plants with insecticidal soap.
Chemical Control of Garden Pests
Check with your local Extension System office for available insecticides and the proper application rates.
Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse or guarantee any product and does not recommend one product instead of another that might be similar.
Garden Bugs Series
- Making Your Garden Vegetables Less Susceptible to Insect Damage
- Managing Soil Pests in the Garden
- Managing Above-Ground Pests in the Garden