Cucumber Beetle

• Yellow-green beetles with black stripes or spots on cucurbit plants
• Ragged feeding damage on leaves, flowers, and young fruit
• Wilting that progresses from one vine to the whole plant over days — a sign of bacterial wilt
• Holes bored into stems near the soil line by larvae
• Seedlings killed or stunted shortly after transplanting

Adults overwinter in leaf litter and field edges, emerging in late spring when cucurbit seedlings appear. They feed on pollen and plant tissue while transmitting bacterial wilt (Erwinia tracheiphila). Eggs are laid at the soil surface; larvae feed on roots through summer. A second adult generation may emerge in late summer in warmer regions.

1. 01Delay planting a week or two after the first flush of adult emergence — reducing early exposure
2. 02Cover transplants with floating row cover until flowering begins; remove for pollination
3. 03Use yellow sticky traps to monitor adult populations
4. 04Plant resistant or tolerant cucumber varieties where bacterial wilt has been a recurring issue
5. 05Kaolin clay applied to foliage can deter feeding
6. 06Pyrethrin or spinosad sprays applied in the evening can reduce adults — prioritize protecting young transplants

If plants wilt and die within a week or two of transplanting despite no obvious drought stress, bacterial wilt is likely. A local extension office can confirm with a quick field test and advise whether the pressure in your county warrants a different variety selection.

• Cucumber Beetle Management— Penn State Extension
• Cucumber Beetle and Bacterial Wilt— University of Wisconsin-Madison Extension