The striped cucumber beetle is about 1/5 inch long with black head and wings striped with yellow and black. The spotted cucumber beetle is about 1/4 inch long and has a black head and black legs with a yellowish-green body and wing covers with 12 distinct black spots. The larva stage of both species live in the soil and feed on the underground parts of plants.

Cucumber Beetle Habit

Cucumber beetles overwinter as adults in sheltered places, but only the striped cucumber beetle overwinters in large numbers in Illinois. The spotted cucumber beetle migrates in from the south. In spring, they feed on nearby vegetation of fields and woodlots before suddenly appearing in large numbers on vine or bean crops. Adult beetles lay eggs in the soil at the base of the plant on which they are feeding. The larvae hatch and feed on roots for 2-4 weeks before pupating and emerging as adults. There are several generations per year.

Cucumber Beetle Damage

Cucumber beetles are chewing insects and may attack cucumber, bean, melon, squash and pumpkin. In addition, the spotted cucumber beetle feeds on asparagus, corn, and eggplant. These insects are destructive to new seedlings just pushing through the soil. Later in the season, the adults feed on leaves, blossoms, and fruits. As they feed on crops, cucumber beetles may spread bacterial wilt and mosaic, two serious diseases of vine crops. Either the disease or the feeding may cause serious damage or complete crop loss.

Cucumber Beetle Control

Non-chemical: At planting time in spring, cover vine plants with polyester row covers to protect them from cucumber beetles. Remove row covers when blossoms appear, to allow pollinating insects access to the flowers.

Chemical: Contact your county Extension office for current pesticide controls.