Eastern Tent Caterpillar

The eastern tent caterpillar is a social moth larva best known for the conspicuous silken tents it builds communally with its siblings in the branch forks of host trees, most commonly wild cherry, apple, and crabapple. These tents serve as a shared shelter that the colony returns to between feeding bouts and expands as the caterpillars grow throughout spring.

While periodic outbreaks can lead to noticeable defoliation of host trees, the species is a native part of eastern North American forest and orchard ecosystems and rarely causes lasting harm to established trees. Its caterpillars are an important seasonal food source for cuckoos, orioles, and other birds that specialize in eating hairy caterpillars avoided by many other predators.

• Body covered in fine hairs, with a solid white stripe running down the center of the back
• Sides marked with a series of pale blue spots and thin yellow or brown lines
• Head is solid black
• Grows to about 5 cm at maturity
• Larvae feed and rest communally, easily identified by the dense white silk tents built in tree branch forks
• Distinguished from fall webworm by the solid white dorsal stripe and tents built in branch crotches rather than at branch tips

Native to eastern North America, found wherever wild cherry, chokecherry, apple, and related trees grow, including forest edges, hedgerows, and orchards. Caterpillars are active in spring, from shortly after leaf-out through late spring, after which they leave the host tree to pupate.

Eastern tent caterpillars are gregarious, living communally within a silk tent that the colony builds and enlarges together, venturing out in groups to feed on host tree foliage and returning to the tent to rest and digest. They use pheromone trails laid down by scouts to coordinate group movement to and from feeding sites, a relatively sophisticated form of chemical communication among caterpillars. As a native insect, they are an important food source for many bird species and a natural, if sometimes conspicuous, part of the springtime forest and orchard ecosystem.

Adult moths lay a single hardened egg mass encircling a twig in summer, and the eggs remain dormant through winter before hatching in early spring as new leaves emerge. Caterpillars pass through several instars over four to six weeks, feeding communally and expanding their tent, before wandering off individually to spin a yellowish silk cocoon in a sheltered location to pupate. Adult moths emerge roughly three weeks later in early summer, mate, and lay the next generation's overwintering egg mass, completing one generation per year.