Bagworms are actually Caterpillars, the larvae of the Bagworm Moth. In late summer to early fall, Bagworms build small “bags” of twigs, leaves and silk to hold their eggs over the winter. The bags can be up to 2½ inches long.

Damage From Bagworms

The eggs will hatch and the caterpillars emerge from the bags in spring and begin to feed on tree leaves. They are particularly fond of Leyland cypress. A serious infestation can defoliate trees, especially of evergreens. While the bags can be an eyesore, a severe infestation can kill the tree. Timing is important for controlling bagworms, the earlier control measures are applied the better. After the caterpillars are controlled, the bags will remain in the trees until they are removed by hand.

Where Bagworms are Found Geographically

Bagworms are common east of the Rockies, with the exception of upper New England and the Southern tip of Florida. The caterpillars are most active in the spring.

Related or Similar Pests 

Garden Bagworm. Snailcase Bagworm.