Invasive Beetle Species Attacking Ash Trees

Emerald Ash Borer (Courtesy of Prince William County.)

The Tale of the Green Intruder by Prince William County Government 

Emerald Ash Borer is an invasive beetle species that can kill an ash tree within several years if left untreated.

The pest, originally from eastern Russia, northern China, Japan, and Korea, is devastating ash trees across Prince William County, said Valerie Huelsman, a forest health specialist with the county's Environmental Services Mosquito and Forest Pest Management Branch. "It was first found here in 2010; and right now, it's widespread around the county. Basically, if you have an ash tree, you should be looking at it and deciding on a plan on how to deal with the beetle very soon."

Symptoms of trees infested by the wood-boring, green beetle include die back of the branches, peeling bark, and woodpecker damage since woodpeckers feed on the beetle's larvae. The larval stage causes the significant damage to the tree as it feeds on tissues under the bark. D-shaped holes, where adults exit the tree, also show that a tree is infested.

People can choose between several methods to treat their ash trees. "They can do a tree injection treatment, basal spray, or soil drench," Huelsman said. "There are a couple of different products available, so it's best to talk to a certified arborist first."

To help people defray the cost of the treatment, the Virginia Department of Forestry has a cost-sharing program. "In counties where the presence of Emerald Ash Borer has been confirmed, such as Prince William County, only trunk injection treatment will be cost-shared. It will cover up to 50 percent of the treatment, if they get a certified pesticide applicator to do it," Huelsman said of the program.

A list of licensed companies who are certified to apply pesticides in the state is available on the Virginia Department of Agriculture and Consumer Services website. Those interested in the cost-sharing program must apply and meet certain criteria to be approved.  

In order for the treatment to be most effective, trees need be at least 12 inches in diameter at 4.5 feet above the ground, and have 70 percent or more leaves remaining in the crown. People must also be willing to put in some effort to save their tree, Huelsman said. "It has to be a tree that you're willing to commit to continue to treat until the Emerald Ash Borer population declines."

People who suspect that they have ash trees that are infested can call Mosquito and Forest Pest Management at 703-792-6279 for help. "We're always glad to come out and confirm that they do have ash trees and that the Emerald Ash Borer is present and give them advice on what their next steps can be," Huelsman said.

To learn more about ash trees, the Emerald Ash Borer and the county's efforts in controlling the pest, check out the "The Tale of the Green Intruder" for more information.