Bagworm Identification and Control on Evergreens

Brown, horned sacks on evergreens are bagworm (Thyridopteryx ephemeraeformis) cases from last year, filled with eggs hatching in ~1 month. Pick off reachable bags now. When larvae emerge, spray Bacillus thuringiensis (Bt) in late June.

For chemical control, use acephate, bifenthrin, carbaryl, or spinosad—cover all foliage thoroughly. Early treatment is critical; older larvae in bags resist contact insecticides. Hosts include arborvitae, cedar, pine, spruce, and many deciduous trees.