Wheat head armyworm larvae are grayish or greenish gray caterpillars with distinct white, green, and brown lateral stripes. They are distinguished from other armyworms by a relatively larger head with two straight dark bands over the top, and a slender body. The worms hide around the base of the plants during the day. The adult moth has a dark streak running the length of the forewing. The dark streak is interrupted near the middle of the wing and then continues to the outer wing margin.
This insect spends the winter as a pupa in the soil. Moths emerge to lay eggs in the spring, and larvae can be found in wheat by June. There are two generations of wheat head armyworm per year in northern regions. A second moth flight occurs in late August.
First generation wheat head armyworm larvae feed on foliage, and later feed on the ripening seed head. They feed on a variety of grasses and cereal crops and seem to prefer the heads. Timothy is considered to be a preferred host. Damage to wheat kernels is similar in appearance to damage by stored grain weevils, with kernels appearing hollowed out.
No chemical control data or economic threshold studies are available for this insect. Infestations are often limited to field margins. If an outbreak were to occur, any registered contact insecticide should be effective against this insect.
Categories: Small grains, Insects, Mites, Wheat head armyworm
Date: 04/16/2004