If you have an ash tree in your yard anywhere around St. Louis, you need to know about the emerald ash borer. This invasive insect has been in the region for years and has killed a staggering number of ash trees across Missouri. The hard truth is that an untreated ash in our area is very likely to be attacked — so the real question for most homeowners isn't if the borer will arrive, but whether your particular tree is worth treating or should come down.
What Is the Emerald Ash Borer?
The emerald ash borer (often shortened to EAB) is a small, metallic-green beetle native to Asia. The adults nibble on ash leaves, but the real damage is done by the larvae, which tunnel just under the bark and cut off the tree's ability to move water and nutrients. A healthy-looking ash can decline rapidly once an infestation takes hold, and an unprotected ash typically dies within a few years of becoming infested. The beetle attacks all true ash species — green, white, and black ash — regardless of the tree's size or age.
Is It Even an Ash Tree?
Before you worry, confirm what you have. True ash trees share a few telltale features:
- Opposite branching — branches, buds, and leaves grow directly across from each other, not staggered.
- Compound leaves — each leaf is made of 5 to 11 leaflets arranged along a central stem.
- Diamond-pattern bark on mature trees — ridges that form a tight, interlacing diamond texture.
- Canoe-paddle seeds — single, oar-shaped winged seeds that hang in clusters.
If you're unsure, our crews can identify the species during a free visit.
Signs Your Ash Is Infested
EAB damage often starts high in the canopy and works downward, so it can be advanced before it's obvious. Watch for:
- Canopy dieback — thinning leaves and dead branches starting at the top of the tree.
- D-shaped exit holes — tiny, distinctive openings (about an eighth of an inch) where adult beetles emerged.
- Bark splitting that reveals the winding, S-shaped larval tunnels underneath.
- Woodpecker "blonding" — pale patches where woodpeckers have stripped bark to feed on larvae.
- Epicormic sprouts — clusters of new shoots erupting from the trunk or base as the tree struggles to survive.
Why dead ash trees are dangerous. Once an ash dies from EAB, it dries out and becomes brittle fast — far faster than most other dead trees. Limbs and even whole trunks can snap and fall without warning, and that brittleness also makes the tree more hazardous to remove. Don't wait on a dead ash near your home, driveway, or where people gather.
Treat or Remove? Making the Call
The decision usually comes down to the tree's current health and its value to your property:
When Treatment Can Make Sense
A healthy, high-value ash — a mature shade tree in a prime spot, still with a full canopy and little to no dieback — can sometimes be protected with ongoing insecticide treatments applied by a professional. Treatment is a long-term commitment, generally repeated on a regular cycle for as long as you want to keep the tree, and it works best as prevention before heavy damage occurs.
When Removal Is the Better Choice
An ash that has already lost a significant share of its canopy, is heavily infested, or is in decline is usually past the point where treatment is worthwhile. At that stage, the practical and safe choice is removal — ideally before the wood becomes dangerously brittle. Smaller, low-value, or poorly placed ash trees are also often better removed and replaced with a more resilient species.
What to Do With the Empty Spot
If you do remove an ash, you don't have to leave a gap in your landscape. Many St. Louis homeowners use the opportunity to replant with a more resilient, diverse mix of species so a single pest can never wipe out their canopy again. Good local options to ask about include oaks, maples, hackberry, and tulip poplar, among others. And if the old stump is in the way of replanting or mowing, our stump grinding service can clear it below grade so you can start fresh.
Don't Wait Until It's a Hazard
The most common mistake we see is waiting too long. A declining ash that looks "fine for now" can become brittle and unpredictable over a single season, and a dead ash standing near a house, driveway, or play area is a genuine danger — and more expensive and difficult to remove safely than a tree taken down while it still has some structural integrity. If your ash is clearly in decline, it's better to plan its removal than to be forced into an emergency call after a limb comes down in a storm.
We Can Help You Decide
Our experienced crews will look at your ash, assess its condition, and give you an honest recommendation — no pressure either way. If removal is the right call, we handle safe tree removal of brittle, hazardous ash trees, and we can advise on pruning to manage other trees on your property. We serve homeowners across Webster Groves, Kirkwood, and Florissant, along with the rest of St. Louis City and County.
For related reading, see our guide to the 7 signs a tree needs to be removed.