Emerald Ash Borer (EAB) adults have a slender half inch long almond shaped body that is metallic green in color. They emerge from infested trees in early summer from D-shaped exit holes that are about 1/8” in diameter.
Larvae feed underneath the bark of ash trees creating S-shaped galleries that disrupt the flow of nutrients and water causing a thinning of the canopy, branch dieback, and ultimately tree death. Ash trees have been made popular by their affordability, toughness, and ease of planting, which made them suitable for use throughout urban areas in large numbers. Ash species are also very common species in many natural areas. All North American Ash species are susceptible to the Emerald Ash Borer.
Use of systemic insecticides for prevention and treatment has shown the best success. Prior to infection, the injection of a product called Merit has given very good results. After infection occurs and populations of EAB build, trunk injections of Treeäge will be necessary. Treeäge has just received a special use permit recently for Missouri because of the EAB. Both of these products have shown positive results in Michigan. It is recommended that trees be treated for two consecutive years and every other year thereafter.
Early diagnosis and prevention are extremely important in control efforts. Adult beetles are metallic green in color, ½ inch long and feed on the margins of leaves before depositing eggs on the bark. D- shaped exit holes can be found in the bark and branches of infested trees as it emerges in early and mid summer. Its larvae stage actually causes the most damage as it chews S-shaped galleries beneath the bark into the water conducting tissues of the tree. Crown dieback, sucker sprouts, loose bark, and increased woodpecker activity are also indications that EAB may be present.
Early detection and prevention are extremely important! If an outbreak occurs, surrounding properties with Ash trees will need to be treated. Infested and removed trees should not be used for firewood., they must be destroyed. Research has shown that EAB will not survive if the wood is chipped into 1-inch chips or smaller.
Treatment for EAB is expensive and ongoing, so weigh your options carefully whether it is treatment or removal and replacement with another species. If an Ash tree is unhealthy or showing signs of decline, we recommend a prompt inspection as soon as possible.
For a pdf copy of this factsheet: Emerald Ash Borer