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Asian Longhorn beetleThe Asian Invasion of Chicago

A tree-eating Chinese beetle was found by an amateur bug collector in Chicago in early July. The discovery of the Asian longhorn beetle will likely lead to the cutting and chipping of large numbers of hardwood trees in Chicago in an effort to keep it from spreading, according to a story in the Chicago Tribune.

The beetle is thought to have arrived within the last three years probably in the wood of crates of Chinese imports. Based on surveys the infestation is believed to be limited to about nine city blocks but could grow to one square mile as surveys continue. Entire blocks are likely to lose all their trees according to the article.

The Asian longhorn beetle was found in the state of New York in 1996. Efforts to eradicate it by cutting and chipping infested trees have been underway since it was discovered.

If not eradicated, this beetle species could possibly become a serious tree pest in this country, but it is too soon to tell. It appears to attack healthy, vigorous trees as well as recently felled and stressed trees. It attacks maples, horse chestnut, locust, ashes and elms. In China it attacks other hardwoods including poplars and willows.

Adult beetles have 1 to 1¼ inch long bodies and 2 inch long antennae. The bodies are glossy black with white spots and the antenna have alternating black and white segments (so they appear striped). Adults are active from May to October. The females chew pits in the bark of tree trunks and branches and lay eggs there. The larvae bore holes and feed in the wood. When the adult beetles emerge from the wood they bore a inch diameter hole out of the tree. These holes can be found on branches, trunks and exposed roots. Large piles of coarse sawdust can be found around the bases of trees and caught in tree branches.

The Asian longhorn borer can be confused with native wood borers. A very common native wood borer in northern Minnesota is the white spotted sawyer beetle. The white spotted sawyer beetle also has a black body about one inch long and very long antennae. The female's antennae are faintly banded gray and black and the male's antennae are all black.

Additional information about the Asian longhorn beetle can be found on the Internet. See the USDA Forest Service State and Private Forestry Website at http://willow.ncfes.umn.edu.

Citations:

"City maps battle plan for tree-eating beetle." By Peter Kendal and LeAnn Spencer. Chicago Tribune.

Asian Cerambycid Beetle Pest Alert, USDA Forest Service Northeastern Area, NA-PR-01-97