Bagworm

Courtesy of UNL Extension

The bagworm is a perennial insect pest of arborvitae, juniper, pine, spruce, and many other evergreen species. It attacks certain deciduous trees such as black locust, honeylocust and sycamore. The spread of the bagworm is slow since adult females are unable to fly. Their dispersal over wide areas occurs mainly through movement of infested nursery stock and ornamental plants, or by ballooning (wind dispersal) of small bagworm larvae during early June.

This insect is most easily recognized by the case or bag that the caterpillar forms and suspends from ornamental plants on which it feeds. The bag is made of silk and host leaves and twigs. These materials are interwoven to disguise and add strength to the case. When the caterpillar is mature, the bag may be one to one and a half inches in total length.

Control

• Spray with Bacillus thuringiensis (Dipel), spinosad (Conserve), permethrin (Eight, Astro, Hi-Yield 38 Plus), tebufenozide (Mimic), bifenthrin (Talstar), deltamethrin (DeltaGard)* or other product labeled for caterpillars when bags appear (early June).
• On a small tree, hand-pick and destroy bags.