Webworms form webs that cover branches and leaves of trees. These webs can be several feet in diameter. Larvae can be up to 1 inch long, and have greenish yellow bodies. They have long hairs on their bodies. Larvae feed off leaves. The last generation in the life cycle is the most dangerous to the trees. Webworms start out as pupae in a cocoon in the cracks of rough bark. Adults come out in spring and deposit large amounts of eggs on the leaves of the trees. Instars begin to feed on the leaves and they spin a silk web. The web worms then envelope themselves inside these cocoons. Two to four generations can occur in this life cycle.