Feeding and molting continues until August when pupation occurs. Adults are active in late August and September. Only males leave the bag to mate with females which remain in the bags to lay overwintering eggs. Prior to molting and pupation, larvae attach the bag by silk strands to twigs and close the opening, protecting the larva. It is important to treat during mid-June.
Small larvae are more susceptible to insecticides.
Larger larvae and molting larvae are not easily killed. Insecticides with some residual are preferred. Picking off and burning bags from fall until spring will reduce populations, but is tedious. The presence of bags during winter is a good indication of which plants need to be treated the following year. One generation per year.