PORTLAND, Ore. (KOIN) – An invasive insect known for decimating ash trees throughout North America and Europe was recently discovered in Oregon, state forestry officials announced on Monday. 

The emerald ash borer is considered the most destructive forest pest in North America and had been detected in 34 other states before it was first discovered in Forest Grove on June 30, the Oregon Department of Forestry said. It’s the first discovery of the insect on the West Coast, the state agency added.

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. 

Wyatt Williams, the Oregon Department of Forestry’s invasive species specialist, said the Oregon ash plays an important role in the environment and its loss could have a greater effect on other plants and animals. 

The emerald ash borer was first discovered in Forest Grove by Dominic Maze, an invasive species biologist for the City of Portland. He was waiting outside a summer camp to pick up his children when he noticed several ash trees with D-shaped exit holes in their bark. 

ODF Invasive Species Specialist Wyatt Williams points to a tiny D-shaped exit hole made by an emerald ash borer as it emerged from an ash tree in Forest Grove. The destructive forest pest was first found in Oregon in Forest Grove earlier this summer. Photo courtesy Oregon Department of Forestry

He immediately recognized this as a sign the emerald ash borer had been attacking the tree and soon he spotted the beetles. 

He called the Oregon Department of Forestry and an entomologist and two other invasive species specialists were able to confirm the invasion. 

“It’s an ecologically vital tree as it shades water, keeping it cooler for fish. The roots stabilize streambanks, reducing erosion. And lots of animals, birds and insects eat the seeds and leaves. Losing it will likely have a huge impact on those ecosystems,” Williams said. 

The infested ash trees in Forest Grove were cut down and chipped within 48 hours of the discovery. 

The Oregon Department of Forestry has been preparing for the arrival of the emerald ash borer, which is native to Eastern Asia, for years after it was first found near Detroit, Michigan in 2002 and as it made its way farther west. 

The Oregon Invasive Species Council had already drafted the Emerald Ash Borer Readiness and Response Plan for Oregon to guide the state in its response. The plan was finalized in March 2021. 

The Oregon Department of Forestry used its advance notice that the emerald ash borer was moving west to begin collecting seeds from Oregon ash trees across the state. The department’s goal is to try and preserve as much of the tree’s genetic diversity as possible before it’s lost.

Researchers will test the seeds to see if any have resistance to eastern ash borers and if so, they might be able to breed into local strains and replant them along streambanks.

There are several things the public can do to help the Oregon Department of Agriculture and the Oregon Department of Forestry monitor the spread of the beetle. First, anyone who sees an emerald ash borer should make a report of it online at the Oregon Invasive Species Council Hotline

Second, Oregonians can be proactive in preventing the spread of the emerald ash borer by removing ash trees that are already in poor health or growing in spaces too small for them. Towns should also remove ash trees from approved street tree lists. Portland has already done this. 

Olive trees, which are in the same family as ash, are also vulnerable to the invasive insect species. 

The Oregon Department of Forestry is trying to index as many trees as possible to see how vulnerable local urban forest is to the emerald ash borer. Communities can use software called TreePlotter to help track where all the vulnerable urban trees are. 

Officials recommend planting resistant species in place of the ash trees — like Oregon white oak, incense cedar and Chinese pistache.

Scott Altenhoff, Oregon Department of Forestry’s Urban and Community Forestry Assistance Program manager, said people should also start thinking about ways to use more ash wood. He said these insects will kill trees in Oregon and there may be opportunities to help local woodworkers and artists and keep the wood from going to waste. 

He reminds the public that it’s imperative that ash or any other wood not be moved beyond its local area to avoid spreading any wood-boring pests. 

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. 

The Oregon Department of Agriculture has more information on its website about the emerald ash borer.