Charlotte has a history of severe infestations of cankerworms. Homeowners can help control the population by banding their trees. Banding trees can prevent the cankerworm population from increasing to an unmanageable level.
Each November the City places special traps at scattered locations to monitor the fall cankerworm population. They also monitor the amount of defoliation in the spring to see if it affecting the health of our tree canopy.
The most common product used to trap cankerworms is Tanglefoot. Another alternative is the Bug Barrier Product.
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What is the fall cankerworm?
The fall cankerworm (Alsophila pometraria) 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 fall 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, other insects and disease.
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 around the last week of November. It is important to wait until most leaves have fallen from the trees so they don't get stuck to the tree bands.
Why does Charlotte have a fall cankerworm problem?For the past 30 years, the cankerworm population in Charlotte has continued to grow. Natural controls have not been adequate to bring the cankerworms to a level that isn't harmful to our tree canopy. Aerial spraying in 1992, 1998 and 2008, along with other natural factors, reduced the population for several years. The City started a banding program on street trees, while requesting homeowners and businesses to cooperate in 1990.
The banding efforts have continued for the last 25 years. Entomologists cannot explain why the cankerworm populations continue to increase, but the City's large concentration of old willow oaks may promote the infestation.