Yellow Woollybear
Diacrisia virginica (Fabricius), Arctiidae, LEPIDOPTERA


DESCRIPTION

Adult - With a wingspan of nearly 40 mm, the moth is nearly pure white except for the abdomen and a few black spots on each wing.

Egg - The white to golden-yellow spherical eggs occur in clusters of 50 to 60 and are usually covered with hairs from the body of the moth. Individual eggs are about 0.6 mm in diameter.

Larva - Densely clothed with long and short hairs, the woolly caterpillar may be pale yellow, brownish-yellow, red, or white. It usually blackens in color near the head. A fully grown caterpillar may be as long as 50 mm.

Pupa - Approximately 16 mm long, the reddish-brown pupa is enveloped by a thin, fragile silken cocoon.


BIOLOGY

Distribution - The yellow woollybear is common throughout North America.

Host Plants - Yellow woollybear caterpillars feed on a wide range of garden, field, and ornamental crops as well as weeds. Some vegetable hosts include asparagus, bean, beet, cabbage, carrot, cauliflower, celery, corn, eggplant, onion, parsnip, pea, potato, pumpkin, radish, rhubarb, salsify, squash, sweet potato, and turnip.

Damage - All stages of the foliage-feeding caterpillar consume flowers, leaves, tender stems, and fruit buds, primarily in summer and autumn. Plants may be skeletonized by heavy infestations.

Life History - This insect overwinters in the pupal stage. Cocoons are often found in large numbers beneath a single shelter (old board, tree bark, etc.). In spring, moths emerge and mate. Females soon deposit clusters of eggs on leaves. After about 7 days, the eggs hatch.

Young larvae feed in colonies on the underside of leaves. As they mature, caterpillars disperse and feed on more exposed sites. After feeding for about 4 weeks, woollybears are fully grown and begin to seek sheltered places in which to pupate. Here, caterpillars spin cocoons and spend the next 1 to 2 weeks transforming into moths. The life cycle is then repeated. Several generations are completed each year.


CONTROL

Several natural enemies limit yellow woollybear populations. Eggs are parasitized by Trichogramma wasps and the caterpillars are susceptible to diseases caused by Bacillus thuringiensis and granulosis virus. This insect usually does not become a problem on crops which are being sprayed for other pests. Should an infestation develop, consult the North Carolina Agricultural Extension Service for current recommendations.

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