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Emerald ash borer in Minnesota

Quick facts

  • Emerald ash borer (EAB) is a very destructive insect pest that attacks all species of North American ash.
  • Ash trees are killed if not protected by insecticides.
  • The Minnesota Department of Agriculture has quarantines on ash wood and materials to help control the spread of EAB.

Early detection of infestations can help reduce the spread to other areas. Please report any EAB beetles or tree symptoms you spot at Report a Pest.

Graphic with text: Emerald Ash Borer. Low Activity. It's safe to prune, but use designated ash wood disposal sites. With images of 3 emerald ash borers and the University of Minnesota Extension wordmark.

Current status: Low Activity

Prune and remove ash trees as needed.

Take bark or wood that is at least one inch thick to the nearest ash tree waste disposal site where it will be taken care of before May 1.

The low activity period for emerald ash borer typically begins in November and runs through April.

Why be concerned about emerald ash borer?

Emerald ash borer on leaf.
Emerald ash borer attacks and kills all species of ash trees in the Fraxinus family.

Emerald ash borer (Agrilus planipennis) is an invasive insect native to Asia that arrived in Minnesota around 1990. As of 2023, EAB is found in 36 states from Maine to Florida and west from South Dakota to Texas, as well as Eastern and Midwestern Canadian provinces. 

Emerald ash borer (EAB) has killed hundreds of millions of ash trees across North America. American ash trees in the Fraxinus family have no chemical or physical resistance to EAB, and the insect will infest and kill trees from as small as one inch in diameter to large mature trees. 

Ash tree species killed by EAB:

  • White ash (Fraxinus americana)
  • Black ash (Fraxinus nigra)
  • Green ash (Fraxinus pennsylvanica)

Tree species not harmed by EAB:

  • American mountain ash (Sorbus americana)
  • European mountain ash (Sorbus aucuparia)
  • Showy mountain ash (Sorbus decora)
  • Prickly ash (Zanthoxylum americanum)

Minnesota has one of the largest ash populations in the country with close to one billion ash trees in cities and forests. Losing these ash trees can have extreme ecological consequences on our urban tree canopies and forest ecosystems.

Tips to reduce the spread of EAB

Report any suspected insects or declining ash trees

With early detection and reporting of emerald ash borer infestations, there may be time to protect lightly infested trees in the area or slow the spread to other areas. There have been many cases where the public was the first to find an initial infestation in an area.

Protect healthy trees

You may choose to treat healthy, high-value trees with insecticide to protect them from EAB. Healthy, mature trees improve the attractiveness of a landscape, raise property values, help reduce energy costs, and decrease stormwater runoff. 

Treating ash trees may also help protect other ash trees nearby. Communities that treat 50% of their ash trees with pesticides emamectin benzoate or azadirachtin help preserve the crown condition of nearby untreated ash trees. This finding could be important for community forestry programs thinking about the costs and benefits of treating street and community ash trees. 

Don't move ash wood

Most EAB will generally move only about one-half to one mile a year from infested sites. But with help from people, it can travel hundreds of miles when carried in firewood, other wood products or nursery stock. The Minnesota Department of Agriculture (MDA) monitors the status of EAB and quarantines the movement of ash wood and materials. How can you help?

  • Don't transport firewood when you go camping or buy it for home use; instead, buy the wood you need at local sites or at the campgrounds.
  • During the EAB dormant period from November through April, take ash wood to your nearest ash tree waste disposal site to be processed. 
  • Avoid removal of ash branches, trees and stumps during the EAB beetle active period from May through October. If removal is necessary due to hazardous conditions, follow the MDA’s best management practices for removing ash material in a quarantined area.

Signs and symptoms of emerald ash borer

Ash can tolerate small numbers of EAB larvae. But, as pest numbers rapidly increase, the trees are girdled and killed if left untreated. Trees are often killed in about four years, although it can take as little as two years. When trees are first attacked by EAB, the symptoms are hard to notice.

If you think you have EAB damage on your tree, first make sure your tree is an ash tree using this ash tree identification chart. 

Below are some common signs and symptoms of emerald ash borer infestation, but other problems can cause an ash tree to decline. Look for anything that may cause stress to the tree, such as drought, compacted soil, or root girdling (roots circling the trunk). Minnesota is also home to bronze birch borer and twolined chestnut borer, both metallic wood-boring beetles that may be confused with EAB.


Treating or removing infected ash trees

  • Insecticides could protect the tree if it still has most or all of its canopy.
  • If your ash tree is within 15 miles of a known infestation, it is at a higher risk of being attacked by EAB. See the Minnesota Department of Agriculture EAB status map.
  • If your tree is beyond 15 miles from any known infestation, you do not need to treat it until EAB is confirmed in your area. 
  • The further your ash is from a known occurrence of EAB, the less likely it will become infested.

Replacing ash trees

Consider replacing removed ash with native tree options. When there are more diverse types of trees in the urban landscape, neighborhoods can tolerate future pest problems better.

If you have a forest with ash trees, Managing Ash Woodlands has practical and timely ash management recommendations for woodland owners. We also have advice for Replacement trees for ash woodlands with emerald ash borer.

Authors: Angela Gupta, Extension forestry educator; Vera Krischik, Extension entomologist; Shane Bugeja, Extension educator, Jeff Hahn and Matt Russell

Reviewed in 2024

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