Plant Problem Diagnosis Key / Pests
Cucumber beetles
Acalymma vittatum, Diabrotica undecimpunctata
Yellow beetles with three black stripes, or yellow-green with 12 black spots, that feed on cucurbit seedlings, leaves and flowers. They also spread bacterial wilt, which is often the larger loss.
Signs
- Striped or spotted yellow beetles in flowers and on seedlings.
- Chewed cotyledons, leaves and rinds; scarring on fruit.
- Vines wilting suddenly after beetle feeding (bacterial wilt).
What favors it
Cucurbit plantings early in the season; striped beetles overwinter in leaf litter nearby.
Prevention
- Cover with row cover from planting until flowering, then remove it so bees can pollinate.
- Plant a trap crop of a highly attractive squash (such as Blue Hubbard) at the edge and treat the beetles there.
- Grow varieties less attractive to beetles where available.
Crops it shows up on
Cucumber, squash & melon; Beans & peas.
Often confused with
Sources
- Cucumber beetlesUniversity of Minnesota Extension
- Cucumber Beetles: Spotted or Striped on VegetablesUniversity of Maryland Extension
Treatment by crop
Cultural, biological and chemical options in the order to use them, and notes written for each crop.
Identification is free. Treatment is on the Home and Pro plans.
Questions in the key that lead here
- Look the plant over, leaf undersides included. Are insects, mites, slugs, eggs, webbing or droppings on it?
Yes, something living or its traces - What is on the plant?
Small insects, clustered or flying - Do they fly up when the plant or the soil is disturbed?
No, they stay put or crawl - What kind of insect?
Hard-bodied beetles - Which beetle?
Yellow-green with black stripes or spots
Not a match? Start the key or describe what you see.
More photos
More from university Extension: search Extension pages on cucumber beetles, or find a plant diagnostic lab through your state's Extension.
Other pests
- Aphids
- Bagworms
- Bark beetles of pine and spruce
- Broad mites and cyclamen mites
- Caterpillars
- Cicada and twig-cutting damage
- Colorado potato beetle
- Cutworms
- Elm leaf beetle
- Emerald ash borer
- Flea beetles
- Fungus gnats
- Galls on leaves and twigs
- Hemlock woolly adelgid
- Japanese beetles
- Lace bugs
- Leafminers
- Mealybugs
- Pine sawflies
- Root aphids
- Root-knot nematodes
- Russet mites
- Sapsucker damage
- Scale insects
- Shore flies
- Slugs and snails
- Spider mites
- Spongy moth (gypsy moth)
- Spotted lanternfly
- Squash bugs and stink bugs
- Squash vine borer
- Tent caterpillars and fall webworm
- Thrips
- Whiteflies
- Wood borers