Cabbage Looper
Trichoplusia ni (Hubner), Noctuidae, LEPIDOPTERA

DESCRIPTION

Adult - The cabbage looper moth has a wingspan of about 38 mm. Near the center of each brownish-gray forewing is a silver figure 8 design. The lighter colored hind wings have dark margins.

Egg - The round, greenish-white egg is slightly smaller than a pinhead.

Larva - This green larva tapers from the rear to the head and has 3 pairs of prolegs. Several white stripes run the length of the body. When fully grown, the caterpillar is about 40 mm long and is less noticeably striped. It moves in a characteristic "looping" motion.

Pupa - The green to brown pupa is approximately 19 mm long and encased in a loosely woven silk cocoon. Cocoons occur on vegetation or in the soil litter.

BIOLOGY

Distribution - Native to North America, the cabbage looper is common from southern Canada into Mexico. In the United States, this caterpillar is primarily a problem in the South. Damaging infestations in cotton usually occur after early insecticide applications.

Host plants - The cabbage looper infests a large range of plants. Some cultivated hosts include: crucifers, cotton, potato, spinach, soybean, lettuce, celery, parsley, tomato, chrysanthemum, geranium, and carnation.

Damage - During their 2- to 4-week lifespan, cabbage loopers are voracious foliage feeders. Ragged holes in cotton foliage may be indicative of their presence.

Life history - Cabbage loopers overwinter as pupae attached to host plant foliage which has fallen to the ground. The inconspicuous night-flying moths emerge in the spring and females soon begin depositing 275 to 350 eggs, singly, on the upper and lower surfaces of leaves. About 3 days later (up to 10 days under adverse conditions), young loopers hatch from the eggs and begin feeding. The caterpillars consume foliage voraciously for 2 to 4 weeks before spinning cocoons and pupating. Within 2 weeks the next generation of moths emerge. In North Carolina, 5 to 6 generations may occur each year, primarily on crucifers.

CONTROL

In cotton, cabbage looper populations usually remain low due to a viral disease. Whenever the dead, darkened loopers are found hanging by their hind legs from cotton leaves, controls are usually unnecessary. When damaging infestations do develop, the loopers are usually fairly large and difficult to control. Due to the relative inefficacy of most insecticides now on the market, chemical control should be used only as a last resort. For further information, consult the current North Carolina Agricultural Chemicals Manual.