Fall Armyworm
 Spodoptera frugiperda (J.E. Smith), Noctuidae, LEPIDOPTERA

DESCRIPTION

Adult - The adult moth has a wingspan of about 38.5 mm. The hind wings are white; the front wings are dark gray, mottled with lighter and darker splotched. Each forewing has a noticeable whitish spot near the extreme tip.

Egg - Minute, white eggs are laid in clusters and are covered with grayish, fuzzy scales from the body of the female moth. The eggs become very dark just before hatching.

Larva - The full-grown, green, brown, or black larva is about 30 to 40 mm long and has a dark head capsule usually marked with a pale, but distinct, inverted "Y." Along each side of its body is a longitudinal, black stripe, and along the middle of its back is a wider, yellowish-gray stripe with four black dots on each segment.

Pupa - The pupa, approximately 13 mm long, is originally reddish brown and darkens to black as it matures.

BIOLOGY

Distribution - The fall armyworm is a continuous resident of the Gulf states, the tropics of North, Central, and South America, and some of the West Indies. Each year it migrates as far northward as Montana, Michigan, and New Hampshire, but usually attains significant populations only in the southeastern states.

Host Plants - Corn, sorghum, coastal Bermuda and other plants of the grass family are preferred foods. However, the fall armyworm may attack alfalfa, bean, peanut, potato, soybean, sweet potato, turnip, spinach, tomato, cabbage, cucumber, cotton, tobacco, all grain crops, and clover.

Damage - In the southern Plains states just east of the Rockies and in the deep South, fall armyworms occasionally damage mature stands of grain as well as early, fall-seeded grain crops. However, in North Carolina, damage is restricted to late summer and fall plantings of small grains. During severe infestations, foliage can be completely removed, so that replanting is sometimes necessary.

Life History - Fall armyworms overwinter in tropical areas in several life stages, but usually as pupae. Moths appear in North Carolina during late June. Under favorable temperature conditions, new moths may continue to appear until early November. Each female lays about 1,000 eggs in masses of 50 to several hundred. Two to ten days later, the small larvae emerge, feed gregariously on the remains of the egg mass, and then scatter in search of food. Unlike nocturnal true armyworms, fall armyworms feed any time of the day or night, but are most active early in the morning or late in the evening. When abundant, these caterpillars eat all the food at hand and then crawl in great armies to adjoining fields. After feeding for 2 or 3 weeks, the larvae dig about 20 mm into the ground to pupate. Within 2 weeks, a new moth flight occurs. The moths usually fly several miles before laying eggs. Several generations occur each year in North Carolina.

CONTROL

During favorable seasons, a number of parasitic enemies keep fall armyworm larvae down to moderate numbers. Cold, wet springs seem to reduce the effectiveness of these parasites and allow large fall armyworm populations to develop. Should an infestation occur late in the summer, delay fall planting as long as practical.

The fall armyworm is more difficult to control chemically than the true armyworm. For specific control information, consult the current North Carolina Agricultural Chemicals Manual.