The emerald ash borer is an Asian beetle that has infested ash trees in the northern United States. The beetles feed on — and eventually kill — the trees they inhabit. If you have an ash tree in your yard, take precautions to keep it safe. (A dying tree can shed limbs and harm your property or your family.)
Emerald ash borer larva hatch on ash tree bark and then burrow into the tree to feed on it. This invasion disrupts the tree's nutrition system, which eventually kills it.
Emerald ash borers were first discovered in Michigan and Canada in 2002. The hardy beetle has since spread east to Massachusetts and west to Colorado, mostly due to people transporting infested trees or wood to noninfested areas.
Early detection can be difficult but is key to preventing spread. Start by learning the general warning signs of a sick or dying tree. Also look for woodpecker holes and subsequent bark loss — early signs of an emerald ash borer infection. As the beetles take over, the tree's leaves will start to thin at the top and then throughout the canopy.
You can sometimes spot vertical splits in the bark where larvae are feeding underneath. Adult emerald ash borers also leave D-shaped holes when they exit a tree. The U.S. Forest Service collected these images to help people identify the emerald ash borer.
States are working to quarantine areas of infested ash trees. But you can help prevent spread by keeping infected wood out of noninfested areas. For instance, only burn firewood cut within 50 miles of your location.
Learn if emerald ash borer has been detected in your area. If you suspect a nearby infestation, insecticides can help protect trees on your property. However, trees already infested should be cut down and burned or buried.