PORTLAND, Ore. (KOIN) – The emerald ash borer, which is considered the most destructive forest pest in North America, was recently discovered in Forest Grove. Across the Columbia River, the city of Vancouver is preparing for the insect’s arrival in Washington. 

The emerald ash borer sighting in Forest Grove was the first confirmation of the invasive insect on the West Coast, according to experts.

The pest, which is native to Asia, was first detected in the United States in Michigan in 2002. In the two decades since then, it’s spread to 35 states, leaving a trail of destruction wherever it goes. 

These invasive and destructive beetles have killed up to 99% of the ash trees in some North American locations. At least five ash species native to the Central U.S. have become critically endangered as the emerald ash borer spreads across the country. 

Within a decade of the emerald ash borer’s arrival in an area, most ash trees will be dead or dying, the Oregon Department of Forestry said, putting the state’s native Oregon ash tree at risk.  

Vancouver Urban Forestry is working with the Washington State Invasive Species Council to continue monitoring for the emerald ash borer’s invasion into Washington. So far, the state has not seen any. 

“Vancouver is reviewing our tree inventory to determine where ash trees are located in parks and on public lands,” said Vancouver Urban Forester Charles Ray. “Private property owners are encouraged to do the same.” 

The greater Vancouver area is home to both the native Oregon ash tree and ash species from the eastern United States and Europe. The Oregon ash plays an important ecological role near waterways and if its population is decimated in the Northwest, it could have consequences for other plants and animals. 

The ash trees in Vancouver are located throughout the urban forest in parks, along streets and near homes. 

The city of Vancouver said tree owners can remove ash trees that are in poor health and replace them with urban tolerant, long-lived trees. Tree removals may require a permit in the city of Vancouver. Residents should contact Urban Forestry at (360) 487-8308 or at urbanforestry@cityofvancouver.us for more information. 

The city recommends people work with a tree care provider to review preventative treatment options

The Washington Invasive Species Council has a page online where people can report sightings of the emerald ash borer in the state. 

The emerald ash borer is about a half-inch long and an eighth of an inch wide. It’s known for its metallic, shiny green color.