Larvae feed on many hosts including corn foliage, apple, pear, cherry, rose, Pawpaw, basswood, chestnut, oak, plum and other trees. There is one generation per year with overwintering in a tough, brown, oval cocoon, retaining the stinging hairs for protection. Eggs are flat-like and laid singly or in groups on leaves. Children sometimes find larvae around shrubs and get stung by handling them. The stiff hairs, or spines, are mildly poisonous, with the sting somewhat less painful than other stinging caterpillars.
Some individuals report severe irritation nevertheless.
Io Moth Adult moths appear at lights from late-May through July. Larvae feed on corn foliage, cotton, roses and a wide variety of trees and shrubs. There is believed to be only one generation in most years with overwintering passed as a pupa inside a tough oval cocoon, often enclosed in leaves on the ground. Moths emerge in the spring and summer, mate and lay eggs. The sting mechanism is similar to the puss caterpillar, but usually less severe.