Emerald Ash Borer in North Texas: Signs, Treatment & What to Do

There is a beetle in North Texas that is going to kill a lot of trees in the next few years, and most homeowners have never heard of it. The emerald ash borer is a small metallic-green insect that tunnels under the bark of ash trees and starves them to death. Texas A&M Forest Service has it confirmed in 40 Texas counties as of this summer, including Collin, Dallas, Denton, and Tarrant. That means every one of our service-area counties is on the list. If you have an ash tree, this article is for you.

What the borer does to a tree

The adult beetle is about half an inch long, bright green, and harmless to look at. The damage comes from its larvae. They hatch on the bark and chew S-shaped tunnels through the layer just under it, the layer that carries water up and sugars down. Cut off enough of that layer and the tree dies from the top down. A healthy-looking ash can be dead within two or three years of infestation. Ash trees have no natural resistance to this insect, none at all.

It came from eastern Asia, showed up in Michigan in 2002, and has been eating its way across the country ever since. First Texas detection: Harrison County, 2016. Now it is here, in the metroplex, and the Texas A&M Forest Service says ash makes up roughly 5 percent of the Dallas-Fort Worth urban forest. That is a lot of dead trees coming, on streets, in parks, and in yards.

Do you even have an ash?

Step one is knowing what is in your yard. A lot of homeowners find out they have an ash only when it starts dying. Check three things: branches that grow directly opposite each other rather than alternating, compound leaves made of many leaflets along a single stem, and bark with a diamond-shaped ridge pattern once the tree is mature. In North Texas the common ashes are green ash, white ash, and Texas ash, planted everywhere in subdivisions from the 70s through the 2000s.

Confirm before you panic. Boxelder looks a lot like ash to the untrained eye, and black walnut gets confused with it too. Neither is borer food. If you are unsure, send a photo with your estimate request. We will tell you what you have. This is also the part where you learn the tree's real condition: our dead vs. dormant checks help you separate stress from decline.

The signs of infestation

The frustrating part is that a lightly infested ash can look fine. By the time the signs are obvious, the beetle has a head start. Here is what to look for, from the earliest to the latest:

Crown thinning from the top down. The upper third of the canopy leafs out sparse or dies back first. A healthy oak or pecan thins in the interior first. Top-down dieback on an ash is the classic early warning.

D-shaped exit holes. When new adults chew their way out, they leave a hole shaped like the letter D, about an eighth of an inch across. Check the trunk and larger limbs. You will not see them from the driveway; get close.

Bark splitting and woodpecker damage. As larvae kill patches under the bark, the bark cracks and splits open. Woodpeckers know what is under there and strip the outer bark to get at the larvae, which leaves pale, blond patches on the trunk.

Sprouts at the base. A dying ash pushes desperate new growth from the trunk base and root flare, thin whips of leaves where the canopy is failing. Watersprouts on the trunk mean the same thing: the tree is in trouble.

If you are seeing two or three of these together on an ash, the borer is the prime suspect. The Texas A&M Forest Service runs an EAB hotline at 1-866-322-4512 for reporting symptomatic trees, and reporting helps them track the spread.

Treatment: the honest math

There is a treatment, and it works, but only in the right window. Preventive trunk injections of systemic insecticide, applied by a licensed pesticide applicator, protect a healthy ash and can save one that is only lightly infested. The insecticide moves through the tree's own plumbing and kills the larvae as they feed. Depending on the product, treatments are repeated every one to three years. It is not a one-time spray from the hardware store; this is professional work with restricted-use products.

Here is the honest part: once the crown has lost roughly half its canopy, treatment stops being worth the money. You would be paying to protect a tree that cannot recover. The City of Dallas treats only significant ash trees that are still in good condition and removes the declining ones. That is the right standard for a homeowner too. If the tree is more than half dead, the answer is removal, done before it becomes a hazard over the driveway.

We are a tree service, not a pesticide company, so we will be straight with you about which side of that line your tree is on. If it is treatable, we will say so and point you to a licensed applicator. If it is not, we handle the removal cleanly and grind the stump so the yard is usable again.

The quarantine rules

The Texas Department of Agriculture has quarantined the confirmed counties, which now include Collin, Dallas, Denton, and Tarrant. The quarantine prohibits moving ash wood, wood waste, and hardwood firewood out of those counties into non-quarantined ones. Firewood is how this beetle travels long distances: a truckload of ash logs can start a new infestation two counties over.

For a homeowner, the rules are simple. You can keep the wood from your own removed ash and burn it where it is. Do not haul it to the lake house in a clean county. Buy firewood where you burn it. Our firewood guide covers the seasoning and storage side; the quarantine covers the moving side. Both matter.

What to do this week

Walk your property and look at every tree with opposite branching and compound leaves. Check the crown from the street, then get close to the trunk and look for D-shaped holes and bark splits. If anything matches, call the TFS hotline to report it, then get a professional assessment. An ash that is still mostly healthy is a treatment candidate. An ash that is half dead is a removal scheduled before the next storm turns it into an emergency.

And plan for the gap. When the ash comes down, the yard loses shade and structure. Fall is the right time to replant in North Texas, and species like cedar elm, chinquapin oak, and live oak take the clay and the heat. Our planting guide covers the timing and the first-summer watering that decides whether the new tree makes it.

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