Emerald Ash Borer

What is EAB?

The emerald ash borer (EAB) is a non-native, invasive wood-boring beetle that feeds on and kills ash trees (Fraxinus spp.), including our native Oregon ash. White fringe trees (Chionanthus virginicus) and cultivated olive (Olea europaea) are also at risk. 

EAB is now permanently established in Oregon and will inevitably spread to Lake Oswego. Once EAB arrives in an area, it cannot be eradicated – which means it doesn’t go away. 

Learn how to identify the EAB.  

Why are ash trees important and what are the impacts of EAB infestation?

Many trees in Oregon are ash trees. Oregon ash (Fraxinus latifolia) is an important native tree that grows along rivers, streams, and throughout the Willamette Valley. Many other types of ash trees are commonly planted throughout communities – in yards, parks, and along streets.  

All species of ash in Oregon are susceptible to EAB. Once an ash tree becomes infested, the tree will die over the course of three to seven years.

Ash trees play a critical role in Lake Oswego's urban forest. Not only do they contribute to the aesthetic value of neighborhoods, they also provide shade, habitat, and erosion control, particularly in riparian zones (wetlands and stream corridors). An EAB infestation could devastate these vital ecosystems, leading to a loss of tree canopy, increased invasive plant growth, and diminished habitat for local wildlife. 

In addition, as ash trees die, they become extremely brittle and can be hazardous to people, property, and infrastructure. Removal of EAB infested trees can be costly.

Learn how to identify ash trees. 

Reducing Impact

While the EAB can not be eradicated and the loss of our ash trees is inevitable, a proactive plan can minimize the ecological, economic, and safety impacts to our community.