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The Emerald Ash Borer (EAB)
The Emerald Ash Borer or Agrilus planipennis, remains the most destructive forest pest ever to enter North America. As of early 2026, it has been detected in 38 U.S. states and 5 Canadian provinces, continuing its steady expansion into the western and southern regions of the continent.
🚩 Signs of Infestation
Because EAB larvae feed on the inner bark (phloem), they effectively starve the tree of water and nutrients. Look for:
- D-Shaped Exit Holes: Small (1/8 inch) holes where adults emerge.
- S-Shaped Galleries: Serpentine tunnels visible under the bark.
- Crown Dieback: Thinning or yellowing leaves starting at the top.
- Woodpecker Damage: "Blonding" of the bark where woodpeckers strip layers to find larvae.
- Epicormic Sprouting: New "sucker" shoots growing from the base of the trunk.
Pro Tip 💡
Experts recommend starting treatments when EAB is detected within 30 miles of your location. If a tree has already lost more than 50% of its canopy, it is likely too late to save and the removal of the tree is highly recommended!
☠️ How does the EAB kills trees?
EAB begins to destroy ash trees by laying eggs between the crevices of the bark. Once the eggs hatch, the larvae will bore into the tree by chewing through the bark, and feeding on the phloem and cambium layers of the tree, which interrupts the flow of nutrients and water. After overwintering in the tree, the metallic green-blue bodied EAB adults (approximately 1/2-inch in length) will emerge in the spring, leaving small, 1/8-inch, diameter D-shape exit holes. From there, they fly off to other nearby ash trees and begin the cycle again. This cycle greatly stresses the ash trees, causing thinning leaves, die-back in the tree’s canopy, bark loss, and eventually, death to the trees.