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Description Bag worms make egg cases that look like brown, leafy ornaments dangling from tree branches. Adult males are small black moths, while adult females are wingless and resemble larvae.
Where they live Bagworms are found in the eastern half of the United States, to the Rocky Mountains and south through Texas.
Their life cycle The "ornaments" are cases made from pieces of leaves and silk spun by last summer's bagworms. Inside every case once inhabited by a female bagworm are up to 1,000 eggs, which hatch in June. Males emerge from pupation in late summer as small black moths to mate with females; females emerge from the cases after laying eggs, then drop to the ground and die.
Plants they attack They eat the leaves of almost any conifer or deciduous tree.
Why they're a problem A large infestation can kill a tree.
Organic damage control Cut off any case you can reach, and be sure to also cut the silk band holding it to the branch. This band will not decompose quickly, and it can girdle the branch and ultimately kill it. Burn the cases, or gather them in a plastic bag, seal it, and throw it in the trash. Birds won't eat bagworm cases, but the larvae are parasitized by a number of species of wasps. If the cases can't be cut out, spray them with BTK (Bacillus thuringiensis var. kurstaki) in early summer, shortly after the larvae hatch. Spraying at other times is ineffective.
