The Minnesota Department of Agriculture recently confirmed Emerald Ash Borer in Carver and Sibley counties, with newly identified trees being located north of Belle Plaine.

While it could be believed that it’s only a matter of time before Emerald Ash Borer (EAB) reaches other parts of the state, there are ways homeowners can slow the spread. Before homeowners make decisions and take action with the trees on their property, it’s important to understand what Emerald Ash Borer is, how to identify it and why it is a problem.

What is Emerald Ash Borer?

Emerald Ash Borer (Agrilus planipennis) is a destructive, invasive species that affects North American Ash trees. It was first discovered in our state in 2009 and 35 other states confirm the presence of EAB. With the additions of Carver and Sibley Counties, it has been identified in a total of 25 Minnesota counties. Emerald Ash borer has killed hundreds of millions of ash trees nationally and with an estimated one billion (or more) ash trees, Minnesota hosts one of the largest concentrations in the country.

How to identify Emerald Ash Borer

Emerald Ash Borer is characterised as a metallic wood boring beetle. Adult beetles are about one third to one half inch long with a slender body. They have a distinctive bright iridescent-green to copper-green color, and may have a copper colored area behind their head. EAB larvae may be more difficult to distinguish from other larvae with their white, flat body and small brownish head.

Risks and Signs of EAB Damage

Higher risk ash trees are generally located within a 15 mile radius of known infestations, however other factors, like presence of non-local firewood, can increase the risk of EAB. There are a number of different signs to look for when scouting for Emerald Ash Borer, such as:

S-shaped canals, or “galleries” will be present beneath the bark

“D” shaped holes in the bark, where adults exit the tree

Evidence of woodpecker holes

Vertical cracking of bark

Thinning canopy

It’s important to note that it may take a couple of years between the time a tree becomes infested and when the tree starts to exhibit symptoms. Additionally, many of these symptoms can be associated with other ash tree decline issues, including other insects, so proper identification is necessary before preventative measures or treatment can be made.

Who should be contacted if a tree is suspected to have EAB?

If you suspect Emerald Ash Borer has damaged your ash trees, contact the Minnesota Department of Agriculture’s Arrest the Pest phone line at 1-888-545-6684 or email at

What can be done to slow the spread of Emerald Ash Borer?

Homeowners have the ability to reduce their risk and slow the spread of Emerald Ash Borer. The MDA recommends firewood should not be moved unless it is MDA Certified Firewood, in addition to avoiding the import of materials that could harbor EAB. Once a location is designated as an EAB quarantine area, it is illegal to move all hardwood firewood out of that area.

Further information about EAB, including county quarantine status and diagnostic tools to help identify infestations can be found on the MDA website at The University of Minnesota Extension also has resources to help with identification, treatment strategies, and alternative tree recommendations when replacing ash trees on their website at

Jason Ertl is a Nicollet County extension educator.

Jason Ertl is a Nicollet County extension educator.

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