Emerald Ash Borer Hits Close to Home


Emerald Ash Borer Hits Close to Home

Emerald Ash Borer (EAB) is an invasive pest that specializes on ash trees, and is considered to be the most destructive forest insect to ever invade the U.S. In 2002, EAB was first detected in the U.S. in Michigan, and is thought to have arrived in wood packing material from its native Asia. Since then, EAB has been found in more than 20 mid-western and eastern states, killing more than 50 million ash trees.

In September of 2013, EAB was found in Boulder, Colorado, and is now on Utah’s front door. We have not yet encountered EAB in Utah, but this pest does pose a significant risk of introduction and establishment. Further, evidence suggests that EAB is generally established in an area for several years before it is detected (see USDA’s EAB Pest Alert for more information).

adult holes
Adult emerald ash borers are colored a distinct, deep metallic green. Their D-shaped exit holes are typical of many flatheaded borers.

EAB adults are bright, metallic, emerald-colored insects and are only about one-half inch long. In the spring, the adults will lay eggs on ash bark, and are particularly attracted to compounds given off by stressed ash trees. Once the eggs hatch, the larvae will bore into the tree, eating the bark and creating S-shaped galleries, where they will eventually pupate and overwinter. The next spring, the new adults will emerge from the tree, leaving behind distinctive D-shaped exit holes. The larvae are the damaging stage of this pest and kill trees by destroying the tree’s water and nutrient conducting tissues.

Obvious signs of EAB damage include thinning of the tree’s canopy, new growth at the base of the tree, bark splits, and woodpecker feeding. Once damage is noticed, however, it is already too late; an EAB infestation is nearly always fatal to the tree. When EAB is found in an area, federal quarantines are enforced to prevent ash timber from being moved out of infested areas.

The Utah Cooperative Agricultural Pest Survey (CAPS) program team has been conducting pest detection surveys for EAB, and is hoping to conduct surveys for EAB again next year in addition to teaching workshops to help inform the public about this pest. If you are interested in participating in these workshops, watch for updates on the Utah CAPS program website. We will know the status of these workshops by mid-summer.

EAB is primarily spread by movement of infested wood by humans. Therefore, we encourage the public to help stop the spread of EAB by not moving firewood and burning wood where you buy it. Also, if you have ash trees in your yard, please check them periodically for signs of EAB. The sooner EAB is detected, the easier and cheaper it will be to control. If you suspect you have EAB in your area, please contact Lori Spears (USU CAPS coordinator; lori.spears@usu.edu) or Clint Burfitt (State Entomologist; cburfitt@utah.gov). Since EAB looks similar to other insects, it is important that trained entomologists examine suspect specimens.


For more information on EAB and related topics, please visit the following websites:

USDA APHIS: www.stopthebeetle.info
USDA Forest Service's EAB site
Multi-agency Emerald Ash Borer website

-Lori Spears, USU CAPS Coordinator


The Cooperative Agricultural Pest Survey is a federal program, administered jointly by USDA-APHIS-PPQ and each state, whose purpose is early detection of invasive species that could threaten U.S. agriculture. In Utah, the program is co-coordinated by Lori Spears (Utah State University) and Clint Burfitt (Utah Department of Agriculture and Food).