Invasive beetle arrives in eastern Washington, threatens ash trees

The emerald ash borer, one of the most destructive invasive pests in the nation, has been detected in multiple trees outside of Walla Walla in eastern Washington .

Late last month, an arborist arrived at a home in College Place, a community southwest of Walla Walla. On an ash tree already in decline, the arborist found signs of a beetle infestation and reported it to the state officials who then sent samples to the U.S. Department of Agriculture, according to the Washington state Department of Agriculture. 

On Wednesday, the federal agency confirmed the identification of multiple specimens found in multiple ash trees in College Place. Also in the trees were larvae and D-shaped holes, typical markings of an emerald ash borer infestation, according to the state Department of Agriculture. 

While it’s the second statewide detection of the beetle, it’s the first time state officials found it infesting trees. In August, officials confirmed identification of an emerald ash borer on a car windshield in Vancouver. 

“We have over a thousand ash trees in our inventory, and that’s just public trees,” said Wes Walker, Walla Walla Parks Maintenance Supervisor. “We don’t know what to expect, but we are aware of what EAB has done in other communities further back east.”

State officials are urging the public to keep an eye out for the pest and report suspected sightings to the Washington Invasive Species Council or via the Washington Invasives app.

There has never been a successful eradication of the emerald ash borer, a metallic green beetle that feeds on wood. The insect has wiped out more than 100 million ash trees in the United States since its initial detection 20 years ago. 

All true ash species are vulnerable to an infestation. 

Without taking action to manage an outbreak, 90-100% of ash trees could be lost within 10-12 years of an initial infestation, according to an analysis by the state Department of Natural Resources. 

Since the detection, Walla Walla and College Place arborists have been surveying public and private lands for signs of the beetle. As of Oct. 16, no additional detections have been confirmed, said Will Rubin, communications manager at the Department of Natural Resources.

The beetle has been active on the West Coast since it was detected in Forest Grove, Oregon, west of Portland, in 2022. It was detected a year later in Vancouver, British Columbia. 

State officials have been preparing for the pest’s arrival for years. Local governments and residents are encouraged to look to the Emerald Ash Borer Resource and Management Guide and the Urban Forest Pest Readiness Playbook when responding to infestations. 

Forestry assistance for municipalities dealing with an outbreak is also available through the Department of Natural Resources as long as funding is available. 

Source: Washington State Standard

This article was originally published by Washington State Standard.