DIY cankerworm management

By on November 6, 2013

Damage caused by the fall cankerworm. Image: Pennsylvania Dept. of Conservation & Natural Resources Forestry Archive, Bugwood.org.

Every spring, countless urban residents see damage to their trees caused by the cankerworm — a small caterpillar that feeds on the leaves of deciduous trees. Not only can they cause trees to look rather unsightly by eating up all their foliage, they can also be annoying when they dangle from their silken strands, dropping onto cars and pedestrians who are in the wrong place at the wrong time.

This is a spring occurrence though, right? So why are we bringing it up now? If you’re one of the sufferers from the appetite of the cankerworm, now is the time to act. Placing sticky bands around your trees now is the best way to safely and effectively manage cankerworm populations before they become a problem in a few months. A little work now can save a big headache later.

The sticky bands work by catching wingless adult female moths. As they emerge from their pupae in the fall, they crawl up the trunk of a tree to the upper branches where they mate with a male, then lay eggs. However, if you intercept them before they make it to their egg-laying sites, then you will probably see considerably less damage. No female ascent means no eggs to hatch next spring.

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

Luckily, it’s fairly easy to do. 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. If there are crevices in the bark, put cotton or insulation between the tape and the tree trunk so that moths can’t just 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.

Finally, solidarity is best. If trees whose crowns are touching are not all wrapped in sticky bands, then they are all in danger. Essentially, the caterpillars can crawl from one tree to another, as long as the branches are touching. So, encourage your neighborhood to work together this holiday season so you can all enjoy the spring season in a few months.

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