Sporting shiny black wings with white spots and long black-and-white banded antennae, the Asian longhorned beetle could be coming soon to trees in your neighborhood. Imported accidentally from China in wood packing material, it has been found by vigilant members of the public in Illinois, New York, New Jersey and Massachusetts. The beetle is about 1 - 1 ½ inches long and is most likely to be spotted in summer to early fall. Often it even has blue feet.
Image courtesy of Melody Keena, USDA Forest Service, Bugwood.org
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
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
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.
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.