Tent caterpillars live in groups within a silken tent.
The silk is produced by glands in the head and the tent provides protection from many natural enemies. Each of these pests has a wide array of natural enemies that usually keep caterpillar populations from becoming large. Harsh weather conditions may also kill many caterpillars. However, one or more of the species may be very common during some years. Although the defoliation and webbing is unsightly, these insects rarely kill a tree.