Emerald Ash Borer

The Emerald Ash Borer (EAB) is an insect that preys on ash trees. The borer is native to Asia and is thought to have been introduced in the United States around 1992. In May 2009, the Emerald Ash Borer was discovered in St. Paul, Minnesota. They have not yet been found in Southern Minnesota, however. The EAB is only about ½” long. It is a bright, iridescent, metallic green and copper color, with a pink-purple color under its wings. The EAB is widest behind its head, tapering off towards its abdomen. The borer is very bright in color and easily identifiable. There are other ash borers present in Minnesota, but none are as deadly as the Emerald Ash Borer. The EAB is only attracted to ash trees and can be devastating to them. Adult EABs feed on the leaves of the ash tree until they mate. The females then lay their eggs in cracks of the tree bark. In 7-10 days, the eggs hatch into larvae which then dig under the bark, creating winding tunnels. These tunnels disrupt the flow of water and nutrients through the tree, the larvae continue this process through fall and they then over-winter as inactive larvae. In the spring when the larvae mature, they will ‘borer’ out of the bark, leaving a D-shaped hole. Generally it takes about 2 years for the damage from the EAB to be noticeable. Thinning foliage and die-back will become apparent at the top (crown) of the tree. Ash trees infested with these insects generally die within 2-4 years. There are treatments available for the borer, however it is recommended that the EAB is confirmed on your tree or on surrounding trees (within 15 miles) before your tree is treated. The treatment can be costly and must be repeated to be effective. If you currently have an ash tree, it is not necessary to cut it down. The borer does not move to other tree varieties and it is not guaranteed to kill your ash tree. The best recommendation is not to plant new ash trees and keep an eye on any ash trees you may currently have.For more information or questions call Berg’s Nursery or go to: University of Minnesota Extension and search 'Emerald Ash Borer'