Bagworms construct and live inside a 1- to 2-inch long tough, tear-shaped portable silken case. These bags are the insect’s most easily seen and identifiable feature. Outside, the silken texture of the bag is somewhat concealed with layers of leaf, twig and bark fragments. The bag has an opening at the larger end that allows the worm to partially crawl out to make repairs to its bag and eat.

Bagworms attack many types of broadleaf and coniferous trees and shrubs. Bagworms are commonly found on junipers, Leyland cypress, Cryptomeria and Thuja (conifers in the cypress family)

Control practices:

(1) Follow proper watering, fertilizing and pruning practices.

(2) Remove other stress factors from trees when possible.

(3) Infested plant material that cannot be treated should be removed and disposed of.

(4) Protect trees from infestation or re-infestation by using sprays containing Acelepryn, Conserve (spinosad) or a pyrethroid (bifenthrin, permethrin, etc.) Watch for and time sprays for bagworm emergence since small worms are much easier to control. This would be approximately late April to early May. Eggs hatch over a 4 – 5 week period so a second spray may be required. Of these insecticides, Acelepryn may have the longest residual action.

(5) Please call the Extension Office if you have questions about spraying, or if you have honeybees near your property for precautions and additional options on spraying for control.

(6) Research indicates that the systemic insecticide Safari (dinotefuran) will control bagworms on trees that are too tall to spray. Apply Safari as a soil drench or through soil injection a month before bagworm emergence to give the insecticide time to be taken up by the plant and to move to the foliage before bagworms begin to feed. Note that use of some systemic insecticides like Safari can cause spider mite populations to increase after treatment.