Vegetable garden insects

Flea beetles

• Tiny beetles, under 1/10 inch, often shiny black, bronze or striped, with enlarged hind legs; they jump like fleas when disturbed.^[11]
• Adults overwinter in weeds and debris; remove garden debris in fall. Insecticides normally aren't necessary and work poorly when numbers are high.^[11]

Cutworms

• Dull brown caterpillars, 1 to 2 inches long, that curl into a C when disturbed and feed at night at or just below the soil surface; mainly a spring pest.^[12]
• Destroy crop residue, keep the garden weed-free in winter, plant extra seedlings or hardy transplants, and use sticky collars to keep climbing cutworms out of berries.^[12]
• Bt or spinosad can protect larger plants; pesticides aren't very effective and aren't recommended on ornamentals.^[12]

Squash bugs

• Flat-backed, grayish-brown bugs about 5/8 inch long with orange stripes along the edges and underside; they feed on squash, pumpkin and melon, causing wilting, plant death and rotting fruit.^[13]
• Bronze to brick-red eggs are laid in clusters of 15 to 40 on the undersides of leaves and hatch in 5 to 10 days; look for and remove them.^[13]
• Keep the garden free of debris where adults overwinter.^[13]

Thrips

• Tiny, slender insects under 1/20 inch that scar and distort leaves, flowers and fruit, leaving silvery or brown patches and dark specks of excrement.^[14]
• Avoid overwatering and excess nitrogen, prune off infested parts, use row covers on small plants, and hang blue or yellow sticky traps to detect them.^[14]
• Oils, soaps and pyrethrins give temporary control and spinosad may work better, but sprays won't restore damaged tissue and rarely work alone.^[14]

Leafhoppers, plant bugs and spittlebugs

• Leafhoppers are wedge-shaped, usually under 1/4 inch, and leave pale stippling on leaves; check leaf undersides because mites, thrips and lace bugs cause similar spotting.^[15]
• Lygus bugs, including the tarnished plant bug, are 1/5 to 1/4 inch with a contrasting triangle on the back; they feed on buds, fruit and shoots, and the injury often appears after the bugs have left.^[16]
• Spittlebug nymphs hide in frothy white masses on stems; adults are stout, about 1/3 inch, and jump or fly when disturbed.^[17]

Grasshoppers

• Grasshoppers are among the hardest garden pests to manage; populations can build in foothills and rangeland after a wet spring and move into gardens.^[18]
• Handpick when numbers are low. Row covers, cones and screened boxes protect plants, but hungry grasshoppers chew through fabric, so metal window screening works better.^[18]
• Birds, blister beetles that eat their eggs, and robber flies are among their many predators.^[18]

Colorado potato beetle

• Adults are convex, 3/8 inch, yellow with black stripes on the wing covers; the hump-backed larvae are red with black spots along the sides. Orange-yellow eggs sit in clusters under leaves.^[1]
• Larvae and adults chew leaves and shoot tips of potatoes and eggplant and occasionally other nightshade-family plants; adults overwinter in the soil, and there are two to three generations a year.^[1]

Mexican bean beetle

• Adults look like copper-colored lady beetles, about 1/3 inch, with 16 black spots in rows of 6, 6 and 4; larvae are yellow and covered with soft spines.^[2]
• Larvae and adults feed on leaf undersides of lima and snap beans, leaving a lacy, skeletonized look. Beans tolerate up to 20% leaf loss before yield drops.^[2]
• Cover rows with row cover after planting, crush yellow egg clusters, larvae and adults by hand, or release the parasitic wasp Pediobius faveolatus in larger plantings.^[2]

Squash vine borer

• Adults are day-flying, wasp-like moths with an orange abdomen, metallic green front wings and clear hind wings; the cream-colored larvae tunnel inside stems.^[3][4]
• The first sign is wilting, often in the morning, then holes near the base packed with moist, sawdust-like frass. In Minnesota adults emerge in late June or early July, and a yellow pan of soapy water traps them for monitoring.^[3]
• Grow less-attacked crops such as butternut squash, cucumbers and melons, plant a second crop of summer squash in early July, or cover vines with floating row cover for about two weeks after the first adult appears, removing it when plants flower.^[3]
• It is one of the most damaging and common pests of squash in home gardens.^[4]

Harlequin bugs and stink bugs

• Harlequin bugs are 3/8-inch, shield-shaped bugs, black with bright red, yellow or orange markings, that leave yellow or white blotches on cabbage-family crops; heavy feeding can kill plants.^[5]
• Handpick bugs and their drum-shaped egg clusters, clear weedy areas, especially mustards, in early spring, and destroy old cole crop plants. Insecticides are generally not recommended for stink bugs in gardens.^[5]
• Stink bugs are shield-shaped with a large triangle on the back; some, such as the spined soldier bug, are beneficial predators. The invasive brown marmorated stink bug is mottled brown, about 5/8 inch, with alternating light and dark bands on the abdomen edges.^[6]

Asparagus beetles

• The common asparagus beetle is 1/4 inch, bluish-black with six cream-colored spots; the spotted asparagus beetle is reddish-orange with twelve black spots. Don't confuse either with beneficial lady beetles.^[7]
• Adult feeding makes spears turn brown and hook over, and common asparagus beetle larvae and adults strip the ferns, weakening plants for next season.^[7]
• Check from early May, in the afternoon when they're most active, and handpick them into a pail of soapy water.^[7]

Onion maggots and wireworms

• Onion maggots are white, legless larvae of small gray flies that tunnel into onion seedlings and bulbs, mainly in cool coastal climates. Avoid heavy manure, use transplants, and cover seedbeds with cloth so flies can't lay eggs.^[8]
• Wireworms are slender, yellowish larvae of click beetles that feed on seeds, seedlings and potato tubers, mostly in soils high in organic matter. Trap them with nearly mature carrots buried every 2-1/2 to 3 feet, pulled and checked every 2 to 3 days.^[9]

Spotted-wing drosophila

• This tiny fruit fly, 1/16 to 1/8 inch with red eyes, lays eggs in healthy ripening cherries, raspberries, blackberries, blueberries and strawberries; males have a dark spot near each wing tip.^[10]
• Sprays at harvest won't help because the maggots are already in the fruit. Harvest early and often, pick up fallen and infested fruit and seal it in a plastic bag in the trash, and cover plants with very fine netting before fruit ripens.^[10]

Sources

1. Texas A&M AgriLife Extension, “Colorado Potato Beetle (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/colorado-potato-beetle-potato-bug/ (accessed 2026-10-06)
2. University of Maryland Extension, “Mexican Bean Beetle (Vegetables).” extension.umd.edu/resource/mexican-bean-beetle-vegetables (accessed 2026-10-06)
3. University of Minnesota Extension, “Squash Vine Borers.” extension.umn.edu/garden-and-home/yard-and-garden/yard-and-garden-insects/squash-vine-borers (accessed 2026-10-06)
4. Texas A&M AgriLife Extension, “Southwestern Squash Vine Borer (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/southwestern-squash-vine-borer/ (accessed 2026-10-06)
5. University of California Statewide IPM Program, “Harlequin Bug (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/harlequin-bug/ (accessed 2026-10-06)
6. University of California Statewide IPM Program, “Stink Bugs (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/stink-bugs/ (accessed 2026-10-06)
7. University of Minnesota Extension, “Asparagus Beetles.” extension.umn.edu/garden-and-home/yard-and-garden/yard-and-garden-insects/asparagus-beetles (accessed 2026-10-06)
8. University of California Statewide IPM Program, “Onion Maggot (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/onion-maggot/ (accessed 2026-10-06)
9. University of California Statewide IPM Program, “Wireworms (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/wireworms/ (accessed 2026-10-06)
10. University of California Statewide IPM Program, “Spotted-Wing Drosophila (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/spotted-wing-drosophila/ (accessed 2026-10-06)
11. University of California Statewide IPM Program, “Flea Beetles (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/flea-beetles/ (accessed 2026-10-06)
12. University of California Statewide IPM Program, “Cutworms (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/cutworms/ (accessed 2026-10-06)
13. University of California Statewide IPM Program, “Squash Bugs (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/squash-bugs/ (accessed 2026-10-06)
14. University of California Statewide IPM Program, “Thrips (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/thrips/ (accessed 2026-10-06)
15. University of California Statewide IPM Program, “Leafhoppers (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/leafhoppers/ (accessed 2026-10-06)
16. University of California Statewide IPM Program, “Lygus Bugs (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/lygus-bugs/ (accessed 2026-10-06)
17. University of California Statewide IPM Program, “Spittlebugs (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/spittlebugs/ (accessed 2026-10-06)
18. University of California Statewide IPM Program, “Grasshoppers (Pest Notes, Home and Landscape).” ipm.ucanr.edu/home-and-landscape/grasshoppers/ (accessed 2026-10-06)