North Central Research Station

Emerald Ash Borer

North Central Research Station entomologists working in East Lansing, Michigan, provide basic information on the biology and ecology of exotic forest insects so managers can formulate proper management strategies.  Over the years, our work has influenced development of policy and regulations to control various pests on regional, national, and international scales.  We are currently helping combat an outbreak of the emerald ash borer, a new exotic pest to North America.

The emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), was discovered infesting and killing thousands of ash trees (Fraxinus spp.) in southeastern Michigan in July 2002.  Evidence now found suggests that A. planipennis first entered Michigan at least 5 to 10 years ago, presumably from solid wood packing materials or dunnage used to transport manufactured goods.  In addition to Michigan, EAB was also found in Ontario in 2002, and in Maryland and Ohio in 2003.

Michigan and Ohio have imposed state quarantines on movement of ash trees and ash wood products to limit human-assisted spread of this pest.  The USDA Animal and Plant Health Inspection Service and the Canadian Food Inspection Agency have imposed Federal quarantines.

Potential Impact

In Michigan, this borer has been observed only on ash trees. It has killed green ash (F. pennsylvanica) , white ash (F. americana), and black ash (F. nigra). The trees die when burrowing larvae girdle the conducting tissues along the main trunk.  Many trees seem to lose about 30 to 50% of the canopy after the first year of attack and the entire tree is often killed after 2-3 years of infestation.  Stress likely contributes to vulnerability.  However, relatively vigorous trees have also been killed by this exotic species.

Ash occurs extensively in the natural and urban forests of the Eastern United States.  In 2001, ash accounted for more than 149 million cubic feet of timber products nationwide.  It is estimated that there are more than a billion ash trees in the United States, of which about 800 million occur in Michigan.  Ash is planted extensively in cities and towns as a hardy urban shade tree.  The quarantines restrict movement of ash logs, lumber, firewood, and nursery stock.