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


Caterpillars will hatch and emerge from the bags in spring and begin to feed on tree leaves. They are especially fond of Leyland cypress trees. A sizable infestation can cause defoliation of trees, especially evergreens. While the bags are unsightly, a severe infestation can kill the tree. Spray timing is important for controlling bagworms, the earlier the better. After the caterpillars are controlled, the bags will remain in the trees until removal.


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

Similar or Related Pests

Snailcase Bagworm, Garden Bagworm