Many Trees Are on the Menu

The female adults lay their eggs in oval depressions chewed into the bark of host trees. Although they favor maples, they also choose birch, willow, elm, locust, horsechestnut and several other types of trees. When the eggs hatch the larvae burrow under the bark and eventually kill the tree by eating the tissues that conduct water and nutrients from the roots and leaves of the tree.

Photo courtesy of Thomas B. Denholm, New Jersey Department of Agriculture, Bugwood.org

Look For Exit Holes

Other telltale signs of Asian longhorned beetle activity are the exit holes where the new adults chew their way out of the tree. The exit holes are round and greater than ¼ inch in diameter, or about the size of a pencil eraser. As the beetle chews, it pushes out sawdust. The sawdust collects at the base of the tree when infestations are heavy.

Photo courtesy of Dennis Haugen, USDA Forest Service, Bugwood.org

»  Find out about another tree pest: the emerald ash borer

Similar Looking Beetles

There are a two other beetles native to the eastern United States that could be confused with the Asian longhorned beetle. The cottonwood borer is about the same size as the Asian longhorned beetle, but its antennae are all black and the white marks on its body form stripes rather than distinct spots. The white spotted pine sawyer feeds on dying or dead conifer trees. The female white spotted sawyer looks most like the Asian longhorned beetle. Its antennae are faintly banded with gray rather than white and the body has small patches of white rather than distinct spots.

Controlling the Spread

So far more than 7,000 trees have been cut down in New York and Illinois alone as federal, state and local governments attempt to eradicate introductions of the Asian longhorned beetle. To keep the beetles from spreading to new areas, it is very important not to move firewood or trees potentially hosting the beetle larvae outside of quarantined areas. Because the Asian longhorned beetle can kill so many types of trees, if it spreads further it could devastate forests, street trees and trees in parks. You can help by learning what the Asian longhorned beetle looks like and reporting it to your local cooperative extension office or through one of the web sites listed below.

Photo courtesy of Michael Bohne, Bugwood.org

For More Information:

University of Vermont

USDA Animal Plant Health Inspection Service

Don't Move Firewood

Article by Sylvan Kaufman. Dr. Kaufman is a writer of popular scientific and gardening articles. She is also an ecological consultant.