Insect I.D.: Emerald Ash Borer

LANSING, Mich. – A few weeks ago, a new insect pest was found attacking ash trees in southeast Michigan, according to the Michigan Department of Agriculture (MDA).

The pest, known as the emerald ash borer, is an exotic species previously unknown in North America. Since the pest is highly destructive, the Michigan Department of Agriculture anticipates quarantining the affected counties to prevent further spread. Quarantines are being considered for Livingston, Macomb, Oakland, Washtenaw and Wayne counties.

According to the proposed quarantine, movement of ash trees 1-inch diameter or greater, limbs, firewood, logs and untreated ash lumber to areas outside of the regulated counties is prohibited unless these items are treated and are certified by the MDA. At this time, treatment options for ash logs and lumber include fumigation or kiln drying only. Additional treatments may be permitted once the MDA has evidence of their effectiveness. Movement of ash trees and tree parts within non-infested portions of the state will be handled in the usual manner.

The emerald ash borer adult is dark metallic green in color, ¾-inch in length and 1/16-inch wide. Larvae are creamy white in color and are found under the bark. The emerald ash borer has been found attacking trees stressed by environmental conditions; however, some healthy trees also have been attacked, pointed out Kenneth Rauscher, director, Pesticide & Plant Pest Management Division, Lansing, Mich.

“Usually their appearance goes undetected until the trees show symptoms of being infested – typically the upper third of a tree will die back first, followed by death in two to three years,” he said. “Its host range is limited to species of ash trees in Michigan.”

The MDA asks contractors to report outbreaks of borer-infested ash trees outside the proposed regulated area to their office, the local MSU Extension office or the MDA Ash Borer Hotline at 866/325-0023. More information on the emerald ash borer also can be found on the MDA Web site at www.michigan.gov/mda.

The author is Managing Editor of Lawn & Landscape magazine and can be reached at nwisniewski@lawnandlandscape.com.