Bug Guide
Aphids (many species)
Threat Level: Moderate
Aphids feed in large clusters on cabbage, lettuce, and other plants, distorting growth and transmitting diseases. Identify by pear-shaped green, yellow, brown, red, gray, or black bodies. Prevent with ladybugs, lacewings, hoverfly larvae, parasitic mini-wasps, row covers, or insecticidal soaps.
Scale (Multiple species)
Threat Level: Moderate
Small immobile insects attached to leaves and stems that extract plant juices and secrete sticky honeydew. Use horticultural oils or insecticidal soaps to control heavy infestations. Attract lady beetles.
Mealybugs (Multiple species)
Threat Level: Moderate
Small oval insects clustered on stems and leaves extract plant juices, secreting a sticky residue that promotes mold growth. Blast off heavy infestations with water, or apply insecticidal soaps or horticultural oils. Attract ladybugs, lacewings and parasitic wasps.
Thrips (Multiple species)
Threat Level: Moderate
Tiny fringed-wing insects that rasp leaves and transmit plant viruses. Leaves develop silver scarring or discoloration. Use sticky traps and frequent insecticidal soap applications to manage infestations on onions and cabbage family crops. Attract predatory mites and minute pirate bugs.
Grasshoppers (Multiple species)
Threat Level: Moderate
Hopping insects with large hind legs that chew holes in a wide variety of vegetable leaves, pods and even developing fruit. Hand pick actively feeding grasshoppers. Apply Surround kaolin clay spray as barrier. Attract birds and parasitic flies.
Leafhoppers (Cicadellidae jassidae)
Threat Level: Moderate
Small, wedge-shaped insects that feed on plant sap and can transmit plant diseases.
Slugs (Several species)
Threat Level: Moderate
Slugs leave ragged holes in foliage overnight. Trap in beer or use iron phosphate baits. Attract fireflies, ground beetles, parasitic nematodes and flies.
Ants (Multiple species)
Threat Level: Low
Not damaging plants directly, but they "farm" aphids and other sap-sucking insects for their sugary secretions (honeydew). Manage ants and aphids/scales/mealybugs will likely disappear too. Sticky barriers like Tanglefoot and Diatomaceous Earth can be used to exclude them. A mixture of sugar and borax can be used as bait to control the population.
Whiteflies (Trialeurodes vaporariorum)
Threat Level: Moderate
Clouds of tiny white flies clustered on leaf undersides spread plant viruses. Use yellow traps, insecticidal soaps/oils. Attract lacewings, ladybugs, parasitic wasps.
Leafminers (Several species)
Threat Level: Low
Fly larvae tunnel between leaf layers of spinach/beets. Remove infested leaves. Use row covers to exclude adults. Attract parasitic wasps.
Cutworms (Several species)
Threat Level: Moderate
Caterpillars chew through seedling stems at night. Collar new plants, till in fall to disrupt lifecycle. Apply beneficial nematodes or baits. Attract big-eyed bugs, ground beetles, parasitic tachinid flies.
Cabbage Worms (Pieris rapae)
Threat Level: High
Green inch-long caterpillars chew brassica leaves. Stunt growth when left unchecked. Use row covers at planting or apply Bt/spinosad regularly. Attract parasitic braconid and tachinid flies or trichogramma wasps.
Cucumber Beetles (Acalymma vittata, Diabrotica spp.)
Threat Level: Moderate
Bright yellow and black spotted beetles transmit bacterial wilt. Cover plants until flowering or grow resistant cucumber/squash varieties. Attract ground beetles.
Squash Bugs (Anasa tristis)
Threat Level: High
Flat brown bugs and gray nymphs suck nutrients from squash family crops, killing vines. Use row covers until flowering to exclude them. Trap adults under boards. Attract tachinid flies.
Squash Vine Borers (Melittia cucurbitae)
Threat Level: High
Red and black moths lay eggs that yield caterpillars boring inside squash stems. Foil stems, use row cover early, inject Bt into borer holes. Attract parasitic wasps.
Tobacco Hornworms (Manduca sexta)
Threat Level: Moderate
Large green caterpillars with white bands feed heavily on nightshades. Hand pick pests, use floating row covers, spray Bt/spinosad. Attract parasitic braconid wasps.
Tomato Hornworms (Manduca quinquemaculata)
Threat Level: Moderate
Closely related large green tomato-feeding caterpillars. Control methods same as for tobacco hornworms above.
Grubs (Multiple species)
Threat Level: Moderate
C-shaped white larvae of beetles feed on plant roots below soil surface. Can kill young plants or reduce yields. Apply beneficial nematodes. Attract ground beetles, parasitic wasps and flies. Minimize damage by rotating crops and cultivating soil to disrupt life cycle.
Japanese Beetles (Popillia japonica)
Threat Level: High
Large metallic green and copper beetles with white tufts feeding in clusters quickly skeletonize leaves and damage developing fruit on over 300 host plants. Hand pick aggressively and use pheromone traps to capture and kill. Apply neem oil or insecticidal soap sprays. Attract braconid wasps.
Codling Moths (Cydia pomonella)
Threat Level: High
Caterpillars bore into apples and pears, ruining developing fruit and making them prone to rot. Monitor with pheromone traps. Spray Bt every 10-14 days through fruit development, starting when petals fall. Use fruit bagging technique. Attract parasitic tachinid flies and trichogramma wasps.
Asparagus Beetles (Crioceris asparagi)
Threat Level: Moderate
Adults are black with yellow spots. Larvae feed on spears and ferns, damaging next year’s crop. Clean up debris in fall and use row covers or neem/spinosad sprays. Attract ground beetles to feed on larvae.
Carrot Rust Flies (Psila rosae)
Threat Level: Moderate
Flies lay eggs at carrot/parsnip base. Maggots tunnel roots. Rotate plantings, delay planting date, apply beneficial nematodes. Floating row covers also prevent infestations.
Colorado Potato Beetles (Leptinotarsa decemlineata)
Threat Level: High
Round, striped beetles and reddish larvae skeletonize nightshade leaves. Use row covers, hand pick adults, or apply spinosad/neem sprays. Attract ground beetles.
Flea Beetles (Several species)
Threat Level: Moderate
Tiny jumping beetles riddle potato, eggplant, tomato leaves with holes. Use traps, garlic spray, cover young plants. Apply beneficial nematodes. Attract ground beetles.
Mexican Bean Beetles (Epilachna varivestis)
Threat Level: Moderate
Coppery beetles and fuzzy yellow larvae skeletonize bean leaves. Attract predatory wasps with flowers. Apply spinosad at first signs of damage.
Potato Bugs (Leptinotarsa juncta)
Threat Level: Moderate
Similar to but smaller than the Colorado potato beetle, the false potato beetle has a solid brown or mottled coloration. Both adults and larvae feed on potato foliage and can cause defoliation if populations spike. Practice crop rotation. Attract ground beetles. Apply neem or spinosad for organic control when found in high numbers.
Spider Mites (Tetranychus urticae Koch)
Threat Level: Moderate
These tiny arachnids can cause stippling on leaves and weaken plants by sucking out cell contents.
Earwigs (Forficula auricularia Linnaeus)
Threat Level: Low
Nocturnal insects that may feed on plants and flowers. They can be both beneficial and harmful.
