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Emerald ash borer in Minnesota

Quick facts

  • The emerald ash borer (EAB) is a very destructive insect pest of ash trees.
  • EAB attacks all species of North American ash.
  • Once an ash is attacked by EAB, it will be killed if it is not protected.
  • Ash trees can be protected from EAB with available insecticides.
  • EAB will move only about 1/2 to 1 mile a year from infested sites. But people can carry it hundreds of miles when transporting firewood and other wood products or nursery stock.

Why be concerned about emerald ash borer?

Emerald ash borer on leaf.

Emerald ash borer (Agrilus planipennis) attacks ash trees from as small as one-inch diameter to large mature trees.

This exotic borer is a native of Asia. It was first found in Minnesota in May 2009, in St. Paul. EAB has also been found in many other states, as shown on this map from the USDA. It has also been discovered in Ontario and Quebec, Canada.

The destructive beetle has killed hundreds of millions of ash trees where it has been discovered.

  • There are nearly one billion ash trees in Minnesota, one of the largest concentrations of ash in the country.
  • Ash trees are abundant in Minnesota forests as well as in urban landscapes.
  • Research has found little to no resistance to EAB in our native ash.
  • EAB has also been found to attack white fringetree, not commonly planted in Minnesota.

How to identify emerald ash borer

EAB is a type of metallic wood boring beetle (family Buprestidae). It is a little larger and much more brightly colored than bronze birch borers and two-lined chestnut borers.

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How you can limit the spread of EAB 

  • Be aware of what emerald ash borer looks like as well as the symptoms of an EAB infested tree. Use this diagnostic tool to see if you can clearly rule out EAB.
  • Report any suspected insects or declining ash trees.
    • If you can't easily rule out EAB, then contact the Minnesota Department of Agriculture (MDA) on their Arrest the Pest phone line at 1-888-545-6684 or arrest.the.pest@state.mn.us to report your suspicions. There have been many cases where the public was the first to find an initial infestation in an area.
  • Don't transport firewood when you go camping or are buying it for home use. Buy the wood you need at local sites or at the campgrounds you are visiting.
    • Most EAB will generally move only about 1/2 to 1 mile a year from infested sites. But with help from people, it can travel hundreds of miles when carried in firewood and other wood products or nursery stock.

Damage caused by emerald ash borer

Ash can tolerate small numbers of EAB larvae. But, as the pest rapidly increases in numbers, the trees are girdled and killed.

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What to do about EAB

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Jeff Hahn, Extension entomologist

Reviewed in 2018

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