WSU CAHNRS

CAHNRS and WSU Extension

Wheat and Small Grains

Army Worm

Armyworms can be problematic pests in cereal grains. Armyworms are moth caterpillars that vary in color (gray or green) with a distinct yellow, white, and brown strip along the body. The adult is a yellow-brown moth. Moths emerge in spring months and lay eggs on wheat or barley. Larvae developing from these eggs then feed on wheat from May into the summer.

Symptoms

Research in Washington by Diana Roberts and colleagues noted up to Armyworm35% yield losses due to this insect in spring wheat trials near Davenport. Feeding on wheat heads at night is most common. Characteristic damage is indicated by a small hole bored in the base of florets. However, this pest is generally not an economic concern for most growers.

Prevention

Wheat head armyworm is not typically a pest that causes economic harm, although sporadic indicents of major economic damage have been reported. Due to limited research, it is unclear what strategies work best to control this pest. There is some evidence that biological controls may help limit armyworm populations.

Management

Because the pest does not typically cause economic harm, insecticides are not routinely recommended. Sampling can be done with a sweep net or traps if armyworm populations need to be monitored.

Wheat and Small Grains, P.O. Box 646420 Washington State University, Pullman, WA 99164-6420, 509-335-1719, Contact Us
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