What is a cankerworm?
The cankerworm (Alsophila pometaria) is an insect native to North America. It is typically found from Georgia to Nova Scotia and west to Texas. It has a four-stage life cycle: egg, pupa, larva (caterpillar) and adult.
How does the cankerworm affect trees?
After mating in December, the female moths crawl up trees to lay their eggs on twigs and small branches. As the trees leaf out in the spring, the eggs hatch, leaving small green caterpillars to feed on the leaves. In most cases, the cankerworm will not kill the trees; however, repeated defoliation can weaken trees and make them more susceptible to other stresses, such as age, drought, or other insects and disease. In addition, they create a nuisance to anyone who has ever tried to stroll beneath a willow oak in the spring
What effect will tree banding have on the cankerworm?
Tree banding in November and December is an effective way of controlling the cankerworm. By applying a glue barrier to the tree trunk, the wingless cankerworm moths are trapped as they climb the tree.
For best results, trees should be banded between late November through the end of December. It is important to wait until most leaves have fallen from the trees so they don’t get stuck to the tree bands.
Other Treatment Options
Sometimes despite your best efforts, cankerworms can still be an issue (especially if neighboring properties didn’t join in on the banding fun). In that case there are other options during the active season. One is a systemic treatment applied to the soil (typically takes 24-48 hours for uptake so ideally done right as hatch is beginning), the other is a foliar spray that specifically targets the cankerworms and can be beneficial if the tree is heavily infested to prevent total defoliation.
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