A hungry cankerworm. Image: Joseph Berger, Bugwood.org
The weather is getting warmer, and North Carolinians are eager to emerge from winter and embrace spring. But something else emerges in the warm weather: insects. Almost simultaneously, the weather warms, tree leaves begin to grow, and caterpillars that feed on the leaves of trees hatch. One defoliating pest, the cankerworm, has a history of being problematic and annoying, especially in urban areas of North Carolina.
If you live near Charlotte, you are probably already familiar with the sticky bands placed around the trunks of trees used for cankerworm control. These bands prevent the flightless moths from crawling from the ground into the tops of the trees to lay eggs. When they hatch, these caterpillars can cause major defoliation and reduce the health of our hardwood trees. Typically, less than 50 percent defoliation of a healthy tree occurs.
N.C. State University students are also likely to be familiar with cankerworms. These caterpillars, which belong to the inchworm family, are common across campus. They hang from trees by silken threads and drop onto students’ backpacks and hair as they walk to class… not a good look. The sticky band controls also adorn campus trees.
Sticky band around the trunk of a tree, covered with trapped moths. Image: William A. Carothers, USDA Forest Service, Bugwood.org
Unfortunately, it is too late to use sticky bands to prevent cankerworms this year. If you do find the dangling critters on your windshield every morning, there’s not much you can do about it now. However, being aware of the problem now will help you make decisions about management activities in the fall.
How can you manage cankerworms? Wrap or staple duct tape or paper tree wrap around the trunk of your tree and evenly cover the band with Tanglefoot Insect Barrier. Tanglefoot is a non-toxic, sticky substance that captures the flightless moths, and is available online and at local hardware stores.
Sticky bands should be wrapped around trees close to Thanksgiving (or when leaves fall off the trees) in order to beat the ascent of the egg laying adult moths. So, if you see cankerworms in your yard this spring, offer to host Thanksgiving and use the extra hands to help wrap your trees. What better family activity could there be?