Cucumber beetles are the most important insect pests of vine crops or cucurbits (cucumber, squash, melons, and pumpkins) across much of the United States. The striped cucumber beetle (Acalymma vittatum) and the spotted cucumber beetle (Diabrotica undecimpunctata howardi) occur in the Northeast. The striped cucumber beetle, typically the most common in New Jersey, feeds primarily on cucurbits, whereas the spotted cucumber beetle has a much wider range of host plants. The immature spotted cucumber beetle is called the southern corn rootworm because it feeds on roots of corn. Cucumber beetles can cause losses to cucurbits by direct feeding on young plants, blossoms, and fruit. They also transmit bacterial wilt, which is caused by Erwinia tracheiphila, a particularly important disease of cucumbers and melons.
Natural History
Adult beetles overwinter and leave their hibernating quarters in the spring when temperatures reach 65F degrees or more. When cultivated cucurbit plants begin to emerge through the soil surface, large numbers of beetles may suddenly appear and feed on the seedlings or crawl into soil cracks in reach of sprouting seed. Beetles soon mate and continue feeding throughout the season. Eggs are laid 8-25 days after mating. Females deposit 225-800 in small clusters or singly into soil cracks at the base of cucurbit plants.
Eggs hatch 5-8 days later, widh larvae spending about 15 days feeding on the roots and stems of fruit that is in contact widh the soil. The pupal period is 6-7 days. The time from egg to adult for The first generation of beetles requires about 1 month and slightly longer for succeeding generations.
After cucurbit plants mature and cool autumn weather approaches, beetles migrate to wooded, bushy areas, crawling under litter to overwinter. Some may overwinter a mile from the hatching site. In northern states, only 1 generation occurs while 2 or more generations may be produced in the Gulf states.
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| Cucumber Beetle Larvae |
Spotted Cucumber Beetle (Diabrotica undecimpunctata howardi)
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| Credit:Natasha Wright, Florida Department of Agriculture and Consumer Services, Bugwood.org |
Striped Cucumber Beetle (Acalymma vittatum)
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| Credit: Scott Bauer, USDA Agricultural Research Service |
Management Strategies
- Crop production practices that promote strong root growth and a vigorous crop will make the plants more tolerant to cucumber beetle feeding. Fertilize properly so plants grow rapidly early in the season.
- Early beetle feeding can be avoided by pushing boxes or cones into the ground over the seedlings, open at the bottom and covered with fine netting, as a barrier to the beetles. Remove when plants are established.
- All cucurbits except watermelons are susceptible to bacterial wilt, and control is difficult without insecti- cides. Treat early to prevent beetles from feeding on the seedlings and thus reduce the spread of bacterial wilt. It may be necessary to apply an insecticide treatment every 4 to 7 days as needed until vines begin to run to protect plants.
- Toxic baits, such as Adios, are commercially available. These baits are a mixture of carbaryl insecticide plus a feeding attractant. Before using any pesticide, read and follow all label directions and restrictions. Observe the proper number of days wait before harvest for each particular crop.
Additional Information
Cucumber Beetles - University of Kentucky
NJAES Cucumber Beetle Fact Sheet 225 - Rutgers University
Striped Cucmber Beetle HYG-2139-88 Fact Sheet - Ohio State University
Managing Striped Cucumber Beetle Vine Crops
Bacterial Wilt of Cucurbits - Cornell University
Erwinia tracheiphila - University of Hawaii
