Picture a bug smaller than a penny that can kill a full-grown ash tree in five years. Is this something out of a horror movie? Nope! This scenario is all too real for many property owners across the United States.

This small bug is the Emerald Ash Borer (EAB), and although tiny, it’s killed over a whopping 100 million ash trees in the Eastern United States. In the summer of 2022, it was discovered in Forest Grove, Oregon. If left unchecked, this ash tree pest can destroy many ash trees in the PNW. Below is everything you need to know about EAB and how you can protect your ash trees.


Emerald Ash Borers can kill trees in 10 years or less. These trees were infested in 2006 (left) and were almost all dead in 2011 (right).

What Is It?

The emerald ash borer is a non-native beetle from Asia. It was first discovered in North America in 2002. Since then, the EAB has spread to almost every state in the US and is now invading the West Coast. The beetle attacks all types of ash trees (Fraxinus spp.) regardless of species, size, age, and health condition. This invasive pest is a major problem in both wild forests and urban forests.


Left to right: Adult EAB and immature EAB larva.

Emerald Ash Borer Tree Damage

The EAB feeds on tree sapwood—the layer right underneath the bark. This interrupts water & nutrient transport through the tree and weakens overall tree structure. Other damages include:

  • Leaf loss and canopy dieback.
  • Larval galleries in the wood.
  • D-shaped exit holes in the trunk and branches.
  • Increased woodpecker activity.
  • Weak trees and branches that are more likely to break.
  • Tree death.

Left to right: Tree dieback, larval feeding galleries, D-shaped exit holes.

Emerald Ash Borer Prevention, Treatment, and Management

Successful treatment depends on early action, so be on the lookout! Once trees have more than 30% canopy dieback, chances of treatment and survival are very low. And at about 40-50% canopy dieback, the tree is so weak it's no longer safe to climb. So any removals at this point will need more machinery, cranes, and higher expenses. So, what are your options?


You can combine any of these options along with removals of less valuable trees or trees too far gone to be saved. If you're on a budget, our qualified arborists provide free proposals to space out the tree work over several years.

Don’t let the Emerald Ash Borer ruin your landscape! Inspect your trees regularly to keep your trees, your property, and your community safe. With proper care and attention, you could enjoy your beautiful shade trees for many years to come! So don't hesitate—get started protecting your ash trees today!