FYI, last week, while examining our potato crops, I found a 1/4-inch long, yellow and black striped beetle — the Striped Cucumber Beetle — on one of the leaves! This chewing insect can devastate a crop if allowed to munch and reproduce unchecked. Besides the obvious leaf damage that they do, (which compromises a plant’s ability to photosynthesize, i.e., create food), these insects can oftentimes be vectors of plant diseases such as bacterial wilt and cucumber mosaic virus. The adults feed on squash family plants, beans, corn, peas, and blossoms of many garden plants, often killing the plants. Larvae feed on roots of squash family plants only, killing or stunting the plants. Adults overwinter in dense grass or under leaves, emerging in early-spring to early-summer. Eggs are layed at the base of target plants, and hatch in 10 days. Larvae burrow into the soil to feed on roots for 2-6 weeks, pupate in mid- to late-summer into 1/2-inch, white grubs with brown heads, then, in 2 weeks, emerge as adults to feed on blossoms and maturing fruit. One to two generations per year.
NOTE: Besides the adult beetle’s description, the above information regarding the Striped Cucumber Beetle also applies to the Spotted Cucumber Beetle. See above journal entry for photo of the Spotted Cucumber Beetle.
Striped Cucumber Beetle (adult)
For more info on the Cucumber Beetle, and to see a diagram of the Life Cycles of both the Striped and the Spotted Cucumber Beetles, click here.
To control: Remove and destroy crop residues where adults overwinter. Use floating row covers to protect seedlings and plants, and hand-pollinate (using cotton swabs) the squash family plants. Pile salt marsh hay or straw deeply around plants to discourage beetle movement amongst plants. Apply kaolin clay to uncovered plants, using special care to coat the undersides of leaves, too. Reapply after rain. Hand-pick or vacuum adults, and/or apply parasitic nematodes, (Heterorhabditis bacteriophora), weekly to soil to control the larvae. If all else fails, pyrethrin (a plant-based insecticide), may be applied to beetles seen feeding on pollen in flowers.