Armyworm, Pseudaletia unipuncta (Haw.)

PLANTS ATTACKED: All forage crops.

DESCRIPTION: Adult. Pale-brown or brownish-gray with a wing expanse of about 1 1/2 inches. There is a small but prominent white dot near the center of each forewing.

Larva. The young worms are pale green and have looping habits; older worms do not loop while crawling. The mature larva is about 1 1/2 inches long, greenish brown and has three stripes on each side of the body. The upper stripe is pale orange, the middle one is dark brown, and the bottom stripe is pale yellow. The worm has a smooth skin, honeycombed head, three pairs of true legs and five pairs of prolegs.

LIFE HISTORY: These insects usually pass the winter as larvae in the soil about clumps of grasses. After a short period of feeding in the early spring, they pupate in the soil and moths emerge from the pupal cases about 2 weeks later. The moths remain hidden during the day but are active at night and are attracted to lights. The females lay greenish-white eggs in long rows or clusters on the lower leaves of the host plants, but they frequently are deposited on clothes hung to dry. Each mass is composed of about 50 eggs. Each cluster of eggs is covered with a white adhesive fluid which fastens them together and draws the edges of the leaf. Eggs hatch in 3 to 14 days, depending upon the prevailing temperatures. The larval period extends usually from 20 to 30 days. There are 3 to 5 generations per year.

DAMAGE: The newly hatched larva begins feeding immediately upon foliage, eating the epidermis at first and causing a skeletonized appearance. Older larvae straddle the outer margins of the leaves, especially grass blades, and cut holes reaching to midrib. They often cut the heads off of small grain plants. Although the insects prefer grass crops, they also feed on legumes. After devouring the food supply in an area where they hatched, the larvae move in armies to nearby fields. Usually, most damage to field crops is caused during the spring by first generation larvae.