Text adapted from Turfgrass Pest Management: A Guide to Major Turfgrass Pests in Oklahoma. Oklahoma Cooperative Extension Service.

INSECT AND DESCRIPTION: Armyworm, Pseudaletia unipuncta (Haw.), and fall armyworm, Spodoptera frugiperda (J.E. Smith). Large, active caterpillars up to 1 1/2 inches long when full grown. Both species have longitudinal stripes on the body. Adults are dull colored, night-flying moths with a wing span of 1 1/4 to 1 1/2 inches.

LIFE HISTORY AND HABITS:
Larvae may feed day and night but are more active after dark. They may migrate into lawns from nearby fields or pastures. The true armyworm has 3 or 4 generations per year but is usually found in turf only in the spring. Fall armyworms have several generations from July to November and may damage turf in the fall.

SUSCEPTIBLE PLANTS: All grasses.

DAMAGE CAUSED: Armyworms feed on the leaves and crown of grasses. Only the larvae are injurious.

METHOD OF DETECTION: Pyrethrum test. Treatment may be needed when 5 or more armyworms are found per square yard.

Figure 2. -- "Fall armyworm (larva)", Oklahoma Cooperative Extension Service

Figure 3. -- "Armyworm (adult moth)", Oklahoma Cooperative Extension Service

Figure 4. -- "Fall armyworm (adult moth)", Oklahoma Cooperative Extension Service