Wednesday, March 21, 2012
Bagworms are one of North Carolina’s most pesky insects. Bagworms damage a variety of ornamentals but they are often witnessed on Leyland Cypress, arborvitae, as well as other conifers. Homeowners find bagworms troublesome because getting rid of them requires understanding their life cycle. Timing is everything and most treat bagworms at the wrong time causing frustration, loss of money, and waste of insecticide. Bagworms are identified by their cone shaped bags made of silk and host plant debris, some confuse this as the host plants cones. Usually bagworms are not identified till it is too late, once they are barricaded inside their bags insecticides are useless. To prepare your conifers it is best to look for their bags in early spring or fall before they hatch their eggs. If you see older bags they could be empty or contain 500-1000 eggs, if there are only a few bags it may be best to use hand removal and destroy them, but be careful if they are located in the upper branches. About May through June insecticides containing Bacillus thuringiensis (B.t.), spinosad, or azadirachtin can be used and are not harmful to beneficial insects. If you use products containing bifenthrin be cautious because even though it kills bagworms it will also kill beneficial insects. For more information on bagworms or assistance in identification contact your local Cooperative Extension office.