Pest: Major Pests

Emerald Ash Borer



D-shaped exit hole

Originally from Asia, the emerald ash borer (Agrilus planipennis) was first discovered in Michigan in 2002. It has since caused widespread tree mortality and decline in ash (Fraxinus spp.) trees in Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin.  The emerald ash borer is transported mainly by humans through infected nursery stock, firewood, unprocessed saw logs, and other ash products.

Current Situation

The emerald ash borer (EAB) was identified in Tennessee at a truck stop on I-40 in Knox County in July, 2010. As of July 2020, 65 counties covering the east half of the state are quarantined for the forest pest.

According to the USDA Forest Service and the Tennessee Division of Forestry, an estimated 271 million ash trees in Tennessee, amounting to $11 billion value, could potentially become infested with the emerald ash borer.

Annual Survey

Crown dieback. This was the first tree in TN discovered to have EAB. It was at a truck stop off I-40 west of Knoxville.

USDA Animal and Plant Health Inspection Service, along with the aid of the Tennessee Department of Agriculture, Tennessee Department of Environment and Conservation,  and the University of Tennessee organizes emerald ash borer trapping activities each year. These traps are large, purple triangular traps that resemble a box kite and are hung in ash trees throughout Tennessee. In 2014, 1,224 purple traps were placed across the state of Tennessee.


The adult emerald ash borers are about 1/2 inch long, 1/8 inch wide, and are bronze, golden, or reddish green with darker metallic green wings. The underside is metallic purple-red. The adults can usually be seen from June to August. The larvae are 1 to 1.2 inches long and are white or cream colored.  The larvae make S shaped galleries under the bark of the ash tree. The larvae and galleries can usually be seen year-round.  Once the tree is infested and the emerald ash borer population builds, the leaves begin to wilt and branches die leaving a sparse canopy. D shaped holes, which are 1/8 inch in wide and can be seen year-round, may be noticeable in the branch and trunk where the adult beetles emerged. Early detection is very difficult as it takes 1-3 years of infestation before an ash tree begins to show signs of mortality or decline. Tree mortality is caused when larval feeds on the tissue between the sapwood and the bark thus disrupting the transportation of nutrients and water.  This disruption eventually causes the branches to die first followed by the entire tree.

Management Options

Purple trap used to detect infestations.

Keep ash trees healthy by watering, mulching, pruning, and protected.  Pesticides are available to help combat the emerald ash borer but are not 100% effective yet. Research is ongoing to develop pesticides and other management options to control the emerald ash borer.  Avoid “knee jerk” reactions such as harvesting unifested ash trees. 

Contact a professional forester or your local TDF office for more information on ash and EAB management. Management decisions should consider your current forest management objectives, the amount of ash in your forest, current ash markets, and your proximity to a known EAB infestation.

What Can You Do?

Don’t Move Firewood! Firewood is a very likely transportation method for the emerald ash borer. The beetle is also known to travel in unprocessed ash logs, ash nursery stock, and other ash commodities as. It is very important to know where the emerald ash borer quarantines are if you are traveling between infested states or between counties that are known to be infested.

Learn to recognize what the signs and symptoms are of an infestation. Learn what the emerald ash borer looks like in its various growth stages and immediately contact your county agent, professional forester, or the Division of Forestry at (615) 289-7373 if you suspect your ash tree is infected.


Developing a Community EAB Action Plan - TN

The Green Menace (USDA APHIS)

 Other Resources

Tennessee Department of Agriculture Quarantine Information Page

EAB Media Kit

The Nature Conservancy
  • Department of Agriculture  |  
  • Ellington Agricultural Center  |  
  • 440 Hogan Road  |  
  • Nashville, TN 37220  |  
  • (615) 837-5520  |