Emerald Ash Borer

Emerald Ash Borers (EAB) kill ash trees. EAB is one of the most significant exotic forest pests threatening Minnesota because it has the potential to cause extensive ash tree mortality according to the Minnesota Department of Natural Resources.

Characteristics of an ash tree

  • Branches and buds are directly across from each other and not staggered.
  • Leaves are compound and composed of 5-11 leaflets.
  • Bark on mature trees is tight with diamond-shaped ridges, young tree bark is relatively smooth

What does an Emerald Ash Borer look like

  • It is a slender, elongated insect about 1/3 - 1/2 inch long.
  • It is widest just behind the head, gradually tapering back to the abdomen.
  • It is a bright iridescent green to copper-green color, often with a copper colored area behind the head.
  • It’s body underneath the wings is a purplish-magenta color.

What are the signs of damage from the Emerald Ash Borer

  • Trees typically are killed in two to four years.
  • When trees are first attacked by the borer, the symptoms are inconspicuous and hard to notice. By the end of the second year, thinning foliage and dieback in the crown begins to be apparent. By the third year, there is severe dieback and little foliage.
  • When the adults emerge, they create small, 1/8 inch D-shaped exit holes that are characteristic of this insect, although they can be hard to see.
  • If you were to remove the bark on the trunk of a tree showing these symptoms, you should also find the larval galleries.
  • Woodpecker attacks on ash could also indicate the presence of emerald ash borers. Vertical splits in the bark due to callous tissue forming over old galleries may also be seen.

Reporting sightings of Emerald Ash Borer

  1. Email Arrest the Pest or leave a detailed phone message at 1-888-545-6684.
  2. Send a report through the Great Lakes Early Detection Network App
  3. Login or create an EDDMapS Midwest account and submit a report
  4. Contact the City of Northfield Street & Parks Department


Emerald ash borer in Minnesota: University of Minnesota Extension

Emerald Ash Borer Program: Minnesota Department of Agriculture

Invasive Terrestrial Animals: Minnesota Department of Natural Resources

Minnesota Invasive Terrestrial Plants and Pests Center: University of Minnesota

Animal and Plant Health Inspection Service: U.S. Department of Agriculture

National Invasive Species Information Center: U.S. Department of Agriculture

Information for homeowners: Emerald Ash Borer Information Network

Treatment programs

Biological controls of Emerald Ash Borer: Minnesota Department of Agriculture

How to protect Ash trees