There are four black stripes lengthwise down the back with 12 pale-yellow tubercles armed with spines. There are clusters of spines on orange-red tubercles along each side. Life Cycle and Habits Saddleback Caterpillar Adult moths fly in July and August in the North. 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.