Image shows EAB and D-shaped exit holes from which adults emerge in the spring.
Image shows EAB and D-shaped exit holes from which adults emerge in the spring.
In 2018, emerald ash borer, a tiny wood-boring beetle from Asia, was found in northern Aroostook and York counties in Maine. Emerald ash borer (EAB) is a threat to all ash trees in North America and has already done considerable damage to ash in forests and residential properties across the eastern U.S. 

Emerald ash borer is a metallic-green, wood-boring beetle, only a half-inch in length. Adult beetles feed on the leaves of ash trees, but the major damage to the tree is caused by the larvae feeding under the bark, making serpentine galleries that, in effect, “girdle” the tree, preventing the transport of water and nutrients and resulting in tree mortality within three or four years of infestation. Since the beetle itself is small and the larvae feed under the bark and out of sight, most infestations are identified by signs and symptoms of decline in ash trees, which include crown dieback in a vase-shaped pattern in the center of the crown; splits and cracks in the bark; tiny D-shaped exit holes in the bark, from which adult beetles emerge in spring; evidence of extensive woodpecker feeding known as “blonding,” with large patches of bark chipped off to reveal the paler (“blond”) wood underneath; and epicormic growth, or branches that sprout directly from the trunk below the crown. 

EAB can spread only a few miles a year on its own but can be moved long distances very rapidly in infested timber products, such as firewood. 

Everyone can help slow the spread of the emerald ash borer by learning how to recognize ash trees and the signs and symptoms of infestation, by not moving firewood, and by reporting any suspect trees. Look for “tagged” ash trees in Camden and Rockport and other Maine towns. If you think you have spotted an infested ash tree, report your sighting by calling Maine Department of Agriculture, Forestry and Conservation at 287-2431. For more information about EAB, its life cycle and how to identify signs of infestation and for information about other invasive organisms, visit maine.gov/portal/

about_me/invasives.html. To request a presentation on invasive forest pests or invasive terrestrial plants for your town, garden club or conservation commission, contact Hildy Ellis at Knox-Lincoln Soil & Water Conservation District, hildy@knox-lincoln.org or 596-2040.