EAB Biology and ID

• There are four distinct stages in the life cycle of the emerald ash borer: adult, egg, larval and pupal. As the name implies, the adult beetles are a dark, metallic green color.
• The damage caused by this pest is not caused by the adults at all, but rather by the larval stage of the insect. The larvae hatch from eggs laid by adults in early summer and begin feeding beneath the bark of ash trees. In doing so, the larvae destroy the nutrient-conducting tissues of the trees.
• Eventually, the tree begins to die from the top down. After spending the winter within the tree, the larvae turn into adults, bore through the bark, and emerge from the tree in early summer. As these adults bore through the bark, they leave a characteristic ‘D-shaped’ exit hole.

Image by: Purdue Extension

The adults can fly a maximum of 10 miles, though they regularly do not fly more than 1 mile in search of another ash tree on which to mate and lay eggs. Although the adult beetle’s flight distance is relatively short, the beetle can be spread great distances when people move ash trees and logs that are infested with the larvae. Infested trees and logs may show no external symptoms of infestation and when these materials are transported to a new location, the adult insect emerges and seeks new ash trees to attack.

The emerald ash borer website www.emeraldashborer.info is the best location to find more information about EAB biology and ID.

Click on the following link for information concerning The Resource at Risk in North Dakota.