These odd and familiar insects are found throughout North America east of the Rocky Mountains. The larvae make characteristic cases in which they remain while feeding, dragging the case around with them on the plant. The case has various bits of small twigs, foliage, or other plant materials attached to it for structure and camouflage. When the larva is ready to pupate it attaches the case firmly to a twig or fence or some other solid material. The females or most species are without wings and may even remain within the case when they become the adult moth. Males seek them out, enter the case to mate, and the female then deposits her eggs within her case and dies. This species named here is one of the most common species in eastern North America and one that is capable of causing serious damage to plants, feeding on over 100 different kinds. They will attack both hardwoods and conifers. The hanging bags may be mistaken for seed pods or cones.
The presence of just a few cases on a plant can be resolved by hand-removing the bags and disposing of them. A few larvae feeding on a large plant will cause minimal damage, and may not require chemical control. If there is a heavy infestation a foliar spray of a residual insecticide can be effective, preferably applied prior to the new larvae emerging from the case in the spring.