Grape colaspis beetles feeding on corn leaves

While usually a rare pest in corn, the grape colaspis has been found feeding in two corn fields in Cuming County this summer.

The grape colaspis is a rare pest of corn in Nebraska and is usually found in the southern counties. Its larvae damage plants by feeding on root hairs.

The damage appears earlier than damage caused by corn rootworm and can be confused with wireworm or white grub injury, since the feeding causes stunting and purpling of young corn plants. The grape colaspis usually causes root damage to corn planted after red clover, or more infrequently sweet clover, alfalfa, or soybeans.

Adults emerge in mid-June to early July in the Cornbelt. Females lay eggs and the larvae feed on roots in the late summer and early fall. Unlike corn rootworms, the larvae overwinter. Adults have been reported feeding on corn silks but rarely leaves.

Colaspis beetles are similar in size to corn rootworm beetles but are more of a brownish color with light stripes. The larvae are smaller and more rounded than corn rootworm larvae, and appear slightly curved (comma shaped). Most larval feeding should be complete in Nebraska and some adults should now be visible in some fields.

Keith Jarvi
Integrated Pest Management
Northeast REC, Norfolk

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Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture.

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