How to Manage Pests

Pests in Gardens and Landscapes

Pest identification and confirmation—Cucumber beetles

Cucumber beetles are very common pests in vegetable gardens and may also attack ripening stone fruit. The most abundant species in California is the western spotted cucumber beetle, Diabrotica undecimpunctata; however, the similar western striped cucumber beetle, Acalymma trivittata, may also cause damage. The western spotted cucumber beetle is greenish yellow and has twelve black spots on its back; the western striped cucumber beetle is yellowish orange and has three black stripes. Cucumber beetles may sometimes be confused with predaceous lady beetles, but can be distinguished by the antennae. Lady beetle antennae are short and stubby; those of cucumber beetles are long and threadlike.

Larvae of the spotted cucumber beetle feed on the roots of corn, small grains, beans, sweet pea, and several grasses but do not usually cause noticeable damage in gardens. The striped cucumber beetle larva feeds exclusively on cucurbit roots and can damage these crops when infestations are heavy.

The convergent lady beetle
The convergent lady beetle
Western spotted cucumber beetle
Western spotted cucumber beetle
Western striped cucumber beetle
Western striped cucumber beetle

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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