The emerald ash borer (EAB) is an exotic beetle native to Asia which attacks and kills ash trees. The adult EAB measures 0.5 inch and can be recognized by its sparkly green coat and purplish red abdomen. However, it’s the larvae that have been damaging and killing ash trees across the eastern and midwestern parts of the United States. Measuring up to an inch in length, these cream-colored pests burrow through ash in S-shaped patterns, feeding on the living tissue in the phloem layer of the ash trees, between the bark and the wood. This interrupts the transport of nutrients and water in the tree, causing it to die. 

First found in Michigan in 2001, EAB has spread all over the region, including 13 states and two Canadian provinces. Seven years after it was first discovered, millions of ash trees have already died as a result of EAB. In spring 2009, EAB was identified in St Paul, Minnesota. This poses a threat to all of Minnesota’s estimated 867 million ash trees, our local economies, plant communities, dependent wildlife, and the quality of our water. 

Signs and Symptoms of EAB:

Decline in growth at the top of the canopy

Roots sprouting from the trunk

Vertical fissures in the bark revealing the S-shaped galleries of the larvae

Increased woodpecker activity on the bark of the tree

D-shaped exit holes on the outside of the tree, 3 to 4 mm in diameter

Prevention and Treatment

Experts suggest considering preventive treatment if you have ash trees and live within 10-15 miles of a known infestation. In Minnesota, this includes a large portion of the metro Twin Cities area, as infestations have been found in St. Paul and Falcon Heights. Research into the most effective treatment is ongoing at several large universities. 

Treatment options are available for EAB via local arborists, and some treatments can be applied by the homeowner. Methods include either soil drench or direct injection, using chemicals such as Imidacloprid, but can become costly because they must be repeated annually. These insecticides are relatively new for EAB and are not perfected, meaning that success rates are less than 100 percent. For further details on treatment options, visit the web resources below. 

 If You Suspect Your Ash is Infected:

Contact the Minnesota Department of Agriculture’s Arrest the Pest Hotline at 651-201-6684 to speak with an EAB First Detector, a trained volunteer who will help you determine if this is, in fact, EAB, and if so, guide you through reporting the infestation.

Prevention

To prevent the spread of emerald ash borer, observe the Hennepin and Ramsey County quarantines which prohibit the following transport of Ash:

Entire ash trees (mature or nursery)

Ash limbs or branches

Ash logs

Untreated ash lumber with bark attached or ash bark chips

Any firewood of non-evergreen species