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Bean leaf beetle (Cerotoma trifurcata), an occasional pest of beans, chews roundish holes in cotyledons, leaves, and pods. Adult beetles are about ¼ inch, oval in shape, and have a characteristic rear-pointing black triangle behind the head of each wing. Body color is either greenish-gray or dark red. There can be four additional back spots on wings or spots may be missing.

Bean leaf beetle.

(Photo: Ric Bessin, University of Kentucky)

Bean leaf beetle.

(Photo: Ric Bessin, University of Kentucky)

Management:

• Monitor adult insects on seedling plants, and look for damage to cotyledons and leaves.
• Control with insecticides only as needed, using 20% defoliation or 10% infested plants as a guideline.

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