Small with short hindwing projections. Eggs are laid singly or in stacks under host plant leaves or stems.
Caterpillars are usually solitary and feed on leaves at night.
Older caterpillars make daytime shelters by pulling leaf edges together with silk. Winter form adults hibernate, some first migrating to the south. Overwintered adults fly and lay eggs in the spring until the end of April. The summer form emerges and flies from May-September, laying eggs that develop into the winter form. These adults appear in September or October and soon seek shelter in which to overwinter.