It’s a wrap: DIY cankerworm management

By on November 18, 2015

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Next week, many North Carolinians will be enjoying a turkey feast to celebrate Thanksgiving. Once the tryptophan-induced naps are over, however, it’s time to worry about another feast: the feast that cankerworms enjoy every spring as they feed on deciduous tree leaves.

Cankerworms are a nuisance every year in early spring. Not only do they drop down on a silken thread and onto cars or innocent passersby, but they also eat leaves. Not only does this cause cosmetic damage, more importantly, it causes stress to trees which increases their susceptibility to secondary pests. Typically, these caterpillars are minor pests, but in several urban areas across the state, they have become a severe problem that warrants annual preventative measures.

Sticky band around the trunk of a tree, covered with trapped moths. Image: William A. Carothers, USDA Forest Service, Bugwood.org.

Sticky band around the trunk of a tree, covered with trapped moths. Image: William A. Carothers, USDA Forest Service, Bugwood.org.

Luckily, there is an easy, and inexpensive DIY preventative that can be used, for which we can thank the biology of the insect. The female cankerworm moth does not fly and must ascend the trunk of the tree before she lays eggs in the canopy. So placing a sticky band around the tree will trap the female as she crawls up the trunk of the tree, making her unable to lay eggs and therefore, there will be fewer caterpillars the following spring.

There are two species of cankerworms that cause issues: the fall cankerworm and the spring cankerworm, referring to the time of year that female moths ascend the trunk of the tree. However but both caterpillars emerge each spring near bud break for the tree, feeding on the new foliage. In order to capture both species of moths, the sticky bands must be put up in late fall after the leaves have fallen and left there until bud break the following spring.

So, how can you put these sticky bands up? Wrap or staple duct tape or paper tree wrap around the trunk of your tree and evenly cover the band with Tree Tanglefoot Insect Barrier. Tree Tanglefoot is a non-toxic, sticky substance that captures the flightless moths as they crawl up the trunk. If there are crevices in the bark which leave a gap between the trunk and the wrap, put cotton or insulation between the tape and the tree trunk so that moths can’t crawl underneath. Also, if you have an unusually high population of moths, they may quickly cover the sticky band, so checking it and reapplying Tanglefoot every few weeks may be needed.

Tanglefoot is typically available online and at local hardware stores, but due to a temporary halt in production, you may need to do a little extra hunting for it this year. Production should pick back up early next year, so if you’re unable to find it now, keep an eye out. Late band installment could still reduce the number of spring cankerworms that emerge.

Many neighborhoods band together. There’s a reason for that! If you are the only one who bands your trees, 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. This is one situation where “keeping up with the Joneses” is a good thing!

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