Emerald ash borer (EAB) is a small, metallic-green beetle from Asia that kills ash trees. It was first found in Tennessee in Knox County in 2010 and has since spread across the state. Untreated ash trees almost always die within a few years of infestation.
Is my tree an ash?
- Leaves: made up of 5–11 leaflets on one stem, arranged in opposite pairs.
- Branches: grow directly across from each other (opposite), not staggered.
- Bark: on mature trees, a tight diamond-shaped pattern of ridges.
Signs of emerald ash borer
- Thinning crown — dead branches starting at the top of the tree.
- D-shaped exit holes about 1/8 inch wide in the bark.
- Woodpecker damage — light-colored patches where birds have stripped bark to get at the larvae.
- S-shaped tunnels under loose bark.
- Sprouts growing from the lower trunk as the tree tries to survive.
Treat or remove?
Treatment can work if the tree is caught early (generally less than about 30% of the crown lost) and it's healthy otherwise. Trunk injections by a certified professional can protect a tree for about two years at a time. It's worth considering for large, valuable shade trees.
Removal is usually the better choice if the tree has already lost a big part of its crown, it's not a tree you'd want to keep paying to protect, or it's close to your house, driveway, or play areas.
Why dead ash is so dangerous
Ash wood dries out and turns brittle quickly after the tree dies — much faster than oak or maple. Within a year or two, limbs can snap without warning, and the tree becomes unsafe to climb. That means:
- Removal becomes harder and more expensive the longer you wait, because crews may need a bucket truck or crane instead of climbing.
- Dead ash trees can fail on calm days, not just in storms.
If you have a dead or dying ash near your home, it's one of the tree jobs you shouldn't put off.