In last week’s column, I wrote about bagworms, unwelcome pests that build nests that look like upside-down ice cream cones in evergreens and some hardwoods. Homeowners often refer to all caterpillars that build nests in trees as “bagworms,” but two other species of caterpillars also build unsightly nests in trees: the Eastern tent caterpillar and the Fall webworm.

The Eastern tent caterpillar (Malacosoma americanum) is a species native to much of the United States and southern Canada. Eggs overwinter in an egg mass that encircles a twig and looks as though it has been shellacked. Larvae emerge in early spring and begin to spin their silken nests in the forks of branches, enlarging the nests as they grow.

Favorite trees include apple, black cherry, and chokecherry, but hawthorn, oak, maple, poplar, and other trees also provide food. Larvae leave their nests during the day to feed on young leaves and return at night. They also stay inside on rainy days.

Larvae are brown and hai...