Soybean Looper
Pseudoplusia includens (Walker), Noctuidae, LEPIDOPTERA


DESCRIPTION

Adult - The soybean looper moth has mottled brown forewings with a golden sheen and prominent silver markings near the center. The hind wings are dusky brown. The wingspan ranges from 30.0 to 39.0 mm. Color plate.

Egg - The egg is small, round, and greenish-white.

Larva - This green caterpillar may or may not have pale, longitudinal stripes and small dark spots. The thick body of the looper gradually narrows from the rear to the small head and has three pairs of prolegs. The sixth instar may be as long as 35 mm. Color plate 1, Color plate 2..

Pupa - The pupa of the soybean looper is creamy white or greenish-white with irregular, black spots. Its length is approximately 16.0 mm.


BIOLOGY

Distribution - The soybean looper is found in all areas of the United States where soybeans are grown. However, damaging infestations rarely occur north of Tennessee and North Carolina.

Host Plants - The preferred hosts of the soybean looper are soybean, sweet potato, and peanut. Other hosts include cotton, tomato, crucifers, pea, tobacco, and cocklebur.

Damage - In the Southeast, soybeans are attacked by both cabbage loopers and soybean loopers, but over 90 percent of these are usually soybean loopers. Although loopers infrequently cause pod damage, they are capable of inflicting heavy foliage losses. Defoliation by these pests leaves the plants with a ragged appearance. In North Carolina, damage usually results after a prebloom insecticide application removes most of the looper's natural enemies. Soybean loopers are difficult to control with insecticides.

Life History - In North Carolina, soybean loopers have three or four generations a year. They overwinter as pupae within loosely spun cocoons which are usually attached to plant debris. Soon after adults emerge in the spring, each mated female begins laying an average of 640 eggs, singly, on the upper surface of the host plant leaf. The larvae, which emerge approximately 3 days later, pass through six instars in 2 or 3 weeks. The caterpillars then enter a pupal stage which lasts 1 week during the summer. In North Carolina, looper populations reach a peak in August or September.


CONTROL

Prior to full bloom, chemical control should be employed only if a foliage loss of 35 percent occurs, regardless of the defoliating pest. Fields treated with insecticides prior to bloom have a higher risk of soybean looper infestation than untreated fields. After full bloom, a foliage loss of 15 percent constitutes an economic threshold. For specific control information, consult North Carolina Agricultural Chemical Manual.