Control Bagworms Late May & Early June
Did you notice cone shaped bags hanging from your conifer shrubs or trees last fall? Now is the time to control bagworms. As they say, the early bird gets the worm! The female will lay 300 to 1,000 eggs in each bag, which means they can produce large numbers of offspring in early summer.
Bagworms are in the bag all winter and emerge in spring. Late May and early June are a good time to control the bagworm caterpillar. Determine at what level of infestation you want to spray. Sometimes you can tolerate a few bagworms, but if the population gets out of control this is the time to control them. Apply a pyrethroid such as permethrin or bifenthrin as they have a longer residual life than other insecticides. Remember to not spray any blooming plants as you can inadvertently kill pollinators. Bacillus thuringiensis or BT is a natural control, as it only kills caterpillars. It may need to be re-applied. Always, read and follow label directions. For complete information on chemical control, refer to the North Carolina Agricultural Chemicals Manual. It is available online as a free download.
If you miss spraying in late May-early June, the next best method of control is to remove the bags when they develop. Be sure to carefully cut the silk band that holds the bag on the stem. If you do not it may remain and girdle the branch.
Often native parasitic wasps that will control the bagworms. This natural control often keeps the bagworm population at a minimum, which is often tolerable. Your other option is to select plant material that is not susceptible to bagworms. The preferred conifer plants for bagworms are Leyland cypress, arborvitae, cedar, juniper and pine, but they can feed on other species.
For more information or if you have specific questions about plants in the landscape, garden, or trees, contact Shannon Newton by email at Shannon_Newton@ncsu.edu or by phone at 910-277-2422 at the Scotland County office or 910-875-3461 at the North Carolina Cooperative Extension of Hoke County office.