Bagworm (Thyridopteryx ephemeraeformis)

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Importance- Larvae feed on foliage, rendering the trees weakened and unsightly. The bagworm is an occasional pest on Populus throughout Eastern North American, but common in the east-central United States and destructive only when the insects reach outbreak numbers on favored hosts nearby. Heavily defoliated trees are rare in the forest.

Look For: Sparse foliage all over tree. Brown, silken, football-shaped bags 1½ to 2 inches long, covered with leaves and small twigs on the shoots.

Bagworm Bag

Biology- The female moth deposits her eggs inside the silken bag in the fall. The larvae hatch in the spring, disperse, and build their own bags from which they feed until fall. Because the wingless female never leaves the bag and the larvae feed nearby, damage is usually limited to individual trees.

Monitoring- Examine trees for small bags after the growing season begins. Treat affected trees when defoliation exceeds 80 percent or when trees are defoliated heavily 2 years in a row

Control:

• Hand pick bags when practical.
• Apply a commercial preparation of Bt (Bacillus thuringiensis) as soon as larvae start feeding.
• Spray heavily infested trees with a recommended chemical insecticide for leaf-feeding insects.