Turkey will be the main course for many North Carolinians next week as we celebrate Thanksgiving. After the kitchen is cleaned up however, there’s no time to rest. Instead, it’s time to worry about another main course which you won’t enjoy: the feast that cankerworms enjoy every spring as they feed on tree leaves.
A hungry cankerworm. Image: Joseph Berger, Bugwood.org
Cankerworms are a nuisance in many areas statewide each spring. Not only do these inchworms hang from trees on a silken thread, dropping onto cars or innocent passersby, but they also eat tree leaves. While they’re prevalent in urban areas such as Charlotte, Durham, and Raleigh, cankerworms could be found anywhere. Their leaf-munching can make trees look bad, but the greater threat is that it also causes stress to trees which increases their susceptibility to secondary pests. Cankerworms typically prefer oaks, but will feed on a wide range of hardwood trees.
Luckily, there is an easy DIY that can be implemented now to save you the headache in the spring. For this, we can thank the biology of the insect. Because the female cankerworm moth does not fly and must climb up the tree trunk before she lays eggs in the canopy, by intercepting her before she reaches the canopy, we can prevent egg laying and thus caterpillars in the spring. This can be done by installing a sticky band around the tree that traps female moths as they crawl up the trunk.
Sticky band around the trunk of a tree, covered with trapped moths. Image: William A. Carothers, USDA Forest Service, Bugwood.org
So, how can you put these sticky bands up? It’s simple and requires just a few supplies. First, wrap or staple paper tree wrap or duct tape around the trunk of your tree. Either of these can be found at your local garden supply store. Next, evenly cover the band with Tree Tanglefoot Insect Barrier. Tree Tanglefoot is a non-toxic, sticky substance that the flightless moths get stuck in and are unable to pass as they crawl up the trunk. It can be purchased online (even Amazon carries it!) or at local hardware stores. It is recommended to wear gloves during this step, as Tanglefoot is very sticky and difficult to remove from skin. As the season progresses, check the band regularly. If there is an unusually high population of moths, then they could quickly cover the sticky band rendering it useless, so bands should be checked every few weeks and Tanglefoot reapplied as needed.
Why should you worry about a springtime problem now? It is recommended that sticky bands go up by the end of November to capture the ascending fall cankerworm. Bands should be left up at least until budbreak next spring to capture the spring cankerworm generation as well, which ascends the trunk in early spring. Both cankerworm species eat leaves in the spring, they just make their march towards the tree tops at different times. Keeping these bands up from late November until mid to late March will capture both the fall and spring cankerworm generations.
Many neighborhoods band together to defeat cankerworms and there’s a reason for that. If you are the only one who bands your trees in your neighborhood, and the canopy of your tree touches the canopy of nearby unbanded trees, the moths can easily crawl right over and infest both trees. If both trees are banded, then both are protected. So, get to know your neighbors if you don’t already. A discussion about leaf-eating caterpillars should break the ice!