Egg - The egg mass, laid on the foliage, consists of thin, oval, flattened eggs which overlap like fish scales. Each individual yellow egg is about 1.2 mm long and 1 mm wide.
Larva - Only a few millimeters long when newly hatched, the first instar larva has a large head and uniformly gray body sparsely covered with hairs. A mature larva has a bluish-gray body up to 20 mm long with tiny black transverse stripes. A black stripe with a yellow stripe underneath it runs along each side of the body. The underside of the larva is green mottled with yellow.
Pupa - The yellowish-brown to dark brown, 11- to 12-mm-long pupa can be found in a light gray cocoon with particles of sand enmeshed. The cocoon itself is about 16 mm long and 10 mm wide.
Host Plants - Cabbage, turnip, and related plants are the only known hosts of this pest.
Damage - Because eggs are deposited in masses, individual plants may be infested with large numbers of cross-striped cabbageworms. These caterpillars feed on all tender plant parts but prefer terminal buds. Young leaves and buds are often riddled with holes.
Life History - No biological studies of this pest have been conducted in North Carolina, but in Washington, DC, the cross-striped cabbageworm is reported to produce four generations per year. They probably overwinter as larvae and pupate in spring. Pupation occurs just below the soil surface and lasts about 6 days. Moths emerge from pupae and soon deposit eggs in masses of 20 to 30 on the underside of leaves. Under warm, favorable conditions, eggs hatch in about 6 days. Larvae develop in about 2 to 3 weeks in summer, but require longer to develop during cooler periods of weather.
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