WSU Extension

Hortsense

Dahlia : Western spotted cucumber beetle
(revision date: 2/14/2019)


Biology
The western spotted cucumber beetle is a pest of many ornamentals and vegetables. About 1/4" long, the adult beetles have yellow wing covers with black spots. The rest of the body is black. Adults feed on leaves of plants, while the larvae feed on the roots of some plants.
Management Options

Non-Chemical Management
  • Pick and kill individual beetles.
Select non-chemical management options as your first choice!

Chemical Management

Repeated applications are necessary most seasons. Apply when first observed on plant. Esfenvalerate is toxic to bees. Do not apply products containing esfenvalerate on or near blooming plants. To minimize risk to bees, apply in the evening after bees have stopped foraging for the day.

Images
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Caption: Western spotted cucumber beetle
Photo by: K. Grey
Caption: Western spotted cucumber beetle
Photo by: A.L. Antonelli