Emerald Ash Borer

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Emerald Ash BorerWhat is EAB?

EAB stands for emerald ash borer. It is an insect that attacks and kills all the cultivars of ash trees that grow in Minnesota. The beetle is a small (less than ½ inch) iridescent green bug that feeds on ash trees during the summer. It lays eggs underneath the bark and as the eggs develop into larvae they feed on the cambium underneath the bark denying the tree the nutrients it needs to survive. Ultimately the tree dies over a two to three year period.

Symptoms of EAB Infestation

  • Crown dieback from the top
  • New epicormic (the lower trunk) shoots or growth
  • D-shaped exit holes
  • Bark splitting
  • S-shaped or serpentine shaped galleries formed under the bark
  • Extensive woodpecker damage

What can be done?

D-Shaped Exit HolePesticides are available to effectively treat ash trees but the Department of Agriculture is not recommending the use of these chemicals until the beetle has been located within a 10 mile radius of the city. These pesticides are expensive, $150+ per tree; however they do have a residual effect and can protect the tree for two to three years. Trees can even be saved after they have been attacked if treated promptly.

Another option is to remove the Ash trees systematically over a period of several years and replant with several different varieties of trees other than ash. This would limit the damage that could be done by an infestation of another kind.

What is the City going to do?

EAB has made its way to a number of Minnesota counties, including Hennepin and Ramsey Counties. Though it has not yet been sighted in Hastings, it is only a matter of time when it will be. In order to get a handle on what economic and environmental impacts the bug will have when it does reach Hastings, we need to know how many trees, potentially, it could affect.

Understanding the number of trees, species, and general age of trees will help identify susceptibility to catastrophic events, which will help generate a timeline and map of tree removal, planting, create species diversification, and to apply for grant funds. That is why the City is undertaking a project to inventory all residential and business boulevard and front yard trees in Hastings.

What should you do?

S-Shaped Galleries Under the BarkDo not buy or move firewood if you do not know its identity or source. Movement of infested wood has been the most prevalent way of transporting the pests from infested to uninfested areas. Avoid pruning Ash trees until late fall or winter when trees are dormant. Look for the symptoms of EAB in Ash trees and if you have questions or concerns, contact the City Forester, Paul Mahoney, at 651-480-6177 or call a tree care professional.

For more information, visit the Minnesota Department of Agriculture at and search for “Emerald Ash Borer".