Emerald Ash Borer

Emerald ash borer (EAB) is a non-native (invasive) insect from Asia that kills ash trees. According to the Minnesota Department of Agriculture (MDA), resistance against EAB has not been found in any native North American ash tree populations. In areas where EAB has become established, ash tree mortality rates approach 100 percent. Once emerald ash borer infests an area, it cannot be eradicated. It has killed over 25 million ash trees in the United States.

Minnesota is home to approximately 900 million ash trees, the most of any state, making Minnesota susceptible to the destruction caused by EAB. Trees become infested when adult beetles lay eggs on the bark. The eggs hatch into larvae that bore into the tree, eventually killing it.

EAB was discovered in Minnesota in 2009 in the City of St. Paul. Infestations of EAB were found at Lebanon Hills campground in Eagan in 2014 and near Cedar Avenue and County Road 42 in Apple Valley in 2016. EAB was detected in Lakeville in October 2017, and the City has started preparing for the effects of the infestation.

For the most current map of EAB distribution in Minnesota, visit the Minnesota Department of Agriculture's website.

How to Prepare in Your Yard

The first step is to determine if you have ash trees on your property (PDF).

  • Determine which ash trees you want to preserve or remove.
  • To help residents protect their trees from EAB, the City has created an Ash Tree Injection Program which provides a discounted rate to treat private property ash trees by a local contractor. Ash trees should be 10” diameter or larger and in good physical condition. Request an inspection from Rainbow Treecare, the City's partner in our program. Download a flyer (PDF) for more information on this program.
  • There are several other tree companies that can help protect your ash trees but be sure they are a licensed pesticide applicator. The Minnesota Department of Agriculture's website can help you determine the best tree care company for you.
  • Be aware that the available homeowner and garden center formulations are not concentrated enough to protect an ash tree with a diameter greater than 15” (48” circumference). They may protect it against other pests, but not EAB.
  • Start diversifying the types of trees you plant in your yard. The citywide tree inventory completed in 2017 indicated Lakeville already has too many spruce, maple and crabapples compared to other species. The City’s Annual Tree and Shrub Sale, held each spring, is a great way to diversify the trees in your yard. 
  • If you plan to remove your ash tree, it is best to do it from October 1-May 1 when the beetles are not active, and before the tree has died. Ash trees that have EAB become brittle and dangerous to remove, driving up the cost.

Signs and Symptoms of an EAB Infestation

There are many reasons an ash tree might have dead branches or dieback which can be symptoms of EAB. The best sign to look for is woodpecker activity, where flecks of bark have been stripped away to reveal lighter bark (blonding). This is most easily seen in late winter or early spring. Another sign to look for is bark splits on the trunk or branches.

The City will accept select ash tree inspection requests. Before requesting an inspection, please use the links below to see if your tree is showing the signs and symptoms of EAB.  

Presentation on Emerald Ash Borer in Lakeville

December 5, 2017
Watch this video to hear from experts from the Minnesota Department of Agriculture and Lakeville's City Forester about EAB in Lakeville.

Download the presentation materials (PDF)