Yellowstriped Armyworm
Spodoptera ornithogalli (Guenee), Noctuidae, LEPIDOPTERA


DESCRIPTION

Adult - The yellowstriped armyworm moth has dark forewings with white and brown markings, and white hind wings. The wingspan ranges from 32 to 38 mm.

Egg - Approximately 0.5 mm long and 0.4 mm in diameter, the ribbed, greenish egg gradually becomes pale pink or brown before hatching. The egg mass is covered with scales from the moth's body.

Larva - This smooth-skinned, pale gray to jet black caterpillar has a yellowish-orange stripe along each side and a pair of black, triangular spots on the back of most segments. The sixth larval instar may be as long as 45 mm. Color plate.

Pupa - The brownish pupa is about 18 mm long and 5.5 mm wide.


BIOLOGY

Distribution - The yellowstriped armyworm occurs from New York southward into Mexico, westward to the Rocky Mountains, and in some areas of California and the West Indies. In this country, however, it is most common and most injurious in the southern states. The distribution in North Carolina is statewide.

Host plants - The yellowstriped armyworm is a general feeder. Some of its hosts include alfalfa, bean, beet, cabbage, clover, corn, cotton, cucumber, grape, grass, jimsonweed, morning glory, onion, pea, peach, peanut, sweet potato, tobacco, tomato, turnip, wheat, watermelon, and wild onion.

Damage - This foliage-feeding caterpillar is sporadically injurious to young stands of field crops. Larvae are annually observed in cotton, peanut, and soybean fields and occasionally damage cotton squares and bolls. However, most of its injury consists of defoliating young plants.

Life history - Yellowstriped armyworms overwinter as pupae in the soil. In the southern states, moth emergence begins in early April and continues into May. After mating, the females deposit egg masses on foliage, trees, or buildings. Approximately 6 days later, the eggs hatch and the newly emerged larvae begin feeding. Although these caterpillars emerge by late spring in the South, they may not appear before July in northern and midwestern states. Over a 3-week period, the larvae feed during the day on tender foliage. Mature sixth instars burrow into the soil and change into pupae. Two weeks later, the second generation of moths emerge. In southern states, including North Carolina, three to four generations occur each year.


CONTROL

Yellowstriped armyworms are difficult to control with insecticides. Early detection is important in maintaining populations below economic injury levels. For specific control measures, consult current North Carolina Agricultural Chemicals Manual.