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Asian Longhorned Beetle Update

November 24, 1999

The Asian longhorned beetle, Anoplophora glabripennis, is a native of China, where it feeds on many different types of hardwood trees. The beetle feeds on maples (Acer spp.), including boxelder, sugar, silver, red, and Norway maples. Additional hosts are horsechestnut, black locust, and green ash trees, as well as elms, birches, willows, and poplars. The beetle was first reported in the Ravenswood area of Chicago in July 1998. It arrived in wooden crating material on a ship delivering goods from China.

The adult Asian longhorned beetle is approximately 3/4 inch to 1-1/4 inches long. Its black body is cov-ered with about 40 white spots, predominantly on its abdomen. Its long antennae are 1-1/2 to 2-1/2 times its body length with black and white rings on each segment. Its feet have a blue tinge.

The female chews holes in the bark of trees to lay eggs. Each female is capable of laying from 30 to 70 of them. After she has laid the eggs, she covers them with bark, and plant sap may flow from these wounds. The eggs hatch into white, wormlike larvae that bore into tree trunks and branches. Larval tunneling can girdle tree stems and branches. Later, beetles chew their way out, leaving exit holes about 1/2 inch in diameter. Adult beetles are active from May to October, but they can be found earlier in spring or later in fall if temperatures are warm. During the rest of the year, they are located deep within infested trees. There is probably only one generation per year, and they have no natural enemies in the United States. Four metropolitan areas of Chicago--Ravenswood, Addison, Summit, and Kilbourn Park--have been designated as quarantine zones. The quarantined area covers 14 square miles. In early November, egg-laying sites were detected on American elms in the Cook County Forest Preserve near Rosemont.

Currently, the only method of controlling the Asian longhorned beetle is removing and destroying infested trees. As of November 10, a total of 1,222 trees had been removed from the quarantined zones, and 1,112 trees had been replanted. Replanting began on April 1, and replacement trees include oak, honeylocust, Kentucky coffeetree, hackberry, linden, catalpa, and ginkgo.

The ground surveys that have been used to detect beetle-infested trees have proved inadequate because many of the egg-laying and emergence holes occur on the upper side of branches. As a result, tree climbers with bucket trucks have been utilized to supplement the ground surveys. Surveys will be conducted from November through December 1999 and March through May 2000.

The Illinois Department of Agriculture has established a hotline for homeowners to call if they are concerned about the Asian longhorned beetle. The number is 1-800-641-3934. For information on this unwanted immigrant,consult the following website: http://willow.ncfes.umn.edu/asianbeetle/beetle.htm.

Author: Charles Helm Raymond Cloyd


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