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Asian Longhorned Beetle

August 22, 2008

Asian longhorned beetle, Anoplophora glabripennis, has been found in Deerfield, Illinois. A single adult specimen was found in a parking lot near the corner of Lake-Cook and Waukegan Roads. This insect previously was found in the Ravenswood area of Chicago, as well as in several suburban locations. An aggressive program of tree removal and systemic insecticide application using imidacloprid had apparently eradicated the insect from Illinois. It is still too early to tell whether this find stems from one of the original infestations farther south or is a new introduction. There have also been new finds of this insect elsewhere in North America this year. The previous Illinois infestation apparently resulted from at least three separate introductions.

Asian longhorned beetle adult.

Asian longhorned beetle attacks a variety of trees, including maple, box elder, poplar, plum, alder, birch, willow, horsechestnut, elm, ash, and hackberry. It attacks and kills healthy trees, representing a serious threat to maples and other trees in North America. The adult beetle emerges through a hole that is perfectly round and 3/8 to 1/2 inch in diameter. The beetles are shiny black and about 1-1/4 inches long. They have long antennae banded in black and white, and the back of the beetle has about 40 white spots of various sizes.

After mating, the female chews a 1/4-inch-diameter hole with sloping sides through the bark and lays an egg in the cambium area. This type of hole is diagnostic for this pest, as it is unlike those being produced by any other insect in North America. The egg hatches into a larva that tunnels extensively through the cambium area before eventually tunneling deeper into the wood. Larvae are legless, white, and elongate, with a brown head area. Full-grown larvae approach 3 inches in length and create large tunnels through the wood. Infested trees show severe dieback of the canopy.

The larva pupates in the tunnel that it creates, with the adult chewing the large, round hole in the bark through which it emerges. Adult emergence is most common during June and July, but adults have been found from spring to December. The adult beetles can fly at least 0.6 mile but most commonly fly only to the next host tree, which may be a very short distance.

Author: Phil Nixon


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