Wood Boring Insects in North Texas: Why a Dry Summer Puts Your Trees on the Menu

There is a rule of thumb in arboriculture that surprises most homeowners the first time they hear it: healthy trees are largely uninteresting to wood boring insects. Borers are not random. They are opportunists with a sophisticated ability to find trees that are already struggling, and after the summer Dallas-Fort Worth just went through, there are a lot of struggling trees to find.

That is not a reason to panic. It is a reason to look. A borer problem caught in its first season is a manageable situation. A borer problem discovered after three seasons of tunneling usually is not.

How Borers Find a Tree

Wood boring beetles and moth larvae locate hosts by chemistry. A tree short on water releases a different profile of volatile compounds than a well hydrated one, including ethanol produced in oxygen starved tissue. To a borer flying across a neighborhood, that plume reads as an address.

Once it lands, the insect meets the tree’s defenses, or the lack of them. A vigorous tree pushes back: sap and resin flow into the wound, the tree compartmentalizes the injury, and chemical defenses make the tissue a poor place to raise larvae. All of that costs energy, and energy is exactly what a drought stressed tree has been spending all summer just to stay alive. Defenses fall, the eggs survive, and the larvae begin feeding.

This is why borer outbreaks tend to follow drought years by a season or two, and why a tree that looked fine last year can be riddled this year.

The Borers That Matter in Dallas-Fort Worth

Flatheaded borers, including flatheaded appletree borer. Broad, flattened larvae that mine just under the bark of stressed hardwoods. Common on newly planted and transplanted trees and on sun scalded trunks. Look for D shaped or oval exit holes and flattened, sunken areas of dead bark.

Emerald ash borer. The exception on this list. The other borers here go looking for stressed trees, but emerald ash borer attacks perfectly healthy ash trees too. It is a regulated, highly destructive pest confirmed in North Texas. Signs include thinning from the top of the canopy down, D shaped exit holes about an eighth of an inch across, S shaped galleries under the bark, heavy woodpecker activity, and sprouts along the trunk. Because good health is no protection for an ash, preventive treatment matters, and it is both effective and time sensitive. See our guide on treating an emerald ash borer infestation.

Red oak borer and other oak infesting beetles. Larger larvae that tunnel into the sapwood and heartwood of oaks. Frequently associated with trees already weakened by drought, construction damage, or decline pathogens.

Ambrosia beetles. Tiny beetles that bore into wood and farm a fungus for food. Their calling card is thin toothpick like strands of sawdust protruding from small round holes in the trunk. Strongly associated with stressed and waterlogged trees, which makes them relevant to both this dry summer and a wet winter.

Bark beetles. Small beetles that colonize under the bark, often producing pitch tubes or fine reddish frass in bark crevices.

Tree Borers Identification: What to Look For

Walk your trees deliberately, trunk to canopy, and look for:

• Exit holes. Round, oval, or D shaped, typically an eighth to a half inch across. Shape helps identify the species.
• Frass and sawdust. Fine powder or granular material in bark crevices, at the base of the trunk, or pushed out of holes.
• Sap or ooze. Wet, dark, or foamy streaks running down the bark from a wound point.
• Bark that sounds or feels wrong. Loose, cracked, or sunken patches. Bark that peels away easily to reveal winding galleries underneath is conclusive.
• Woodpecker attention. Woodpeckers are excellent borer detectors. A sudden concentration of woodpecker work on one tree is worth investigating.
• Canopy dieback. Thinning or dead branches in one section of the canopy, often above the point of attack.
• Trunk sprouts. A flush of small shoots low on the trunk is a distress response.

One caution: not every hole is a live infestation, and not every insect on a trunk is a borer. Old exit holes mark an insect that left years ago. Identification drives everything about treatment, which is why it is worth having ISA Certified Arborists confirm what you are looking at.

Tree Borers Treatment: What Actually Works

Treatment depends on the species, the extent of the infestation, and the value and condition of the tree. In broad terms, professional options include:

Systemic insecticide applications. Soil drenches or trunk injections move product into the tree’s vascular system, where feeding larvae encounter it. This is the backbone of ash protection against emerald ash borer, and timing and product selection carry real consequences. Trunk injection is generally preferred for larger, high value trees.

Preventive bark sprays. Applied to trunk and scaffold limbs ahead of the flight period to kill adults as they land and larvae as they chew in. Useful where a known pressure exists and the tree is not yet infested.

Cultural correction, which is the part homeowners control. Restoring water, mulching the root zone, correcting soil compaction, protecting thin bark from sun scald, and avoiding trunk injuries from mowers and string trimmers. These change the signal the tree is broadcasting.

Structural pruning of dead and infested wood. Removing dead and infested limbs sanitizes the tree, reduces breeding material, and improves safety.

Ongoing monitoring. Borers work on a multi year cycle. One inspection tells you where you are; a monitoring plan tells you whether you are winning.

What does not work well: over the counter sprays applied to the bark after larvae are already inside, and waiting to see whether the tree pulls out of it on its own. Once larvae are feeding in the cambium, the timeline belongs to the insect.

Prevention Is Mostly a Vigor Problem

Everything that keeps a tree vigorous is also borer prevention, and none of it involves an insecticide.

• Deep, correct watering. Slow soaks under the outer canopy on a seven to fourteen day cycle in dry weather. Sprinkler zones aimed at turf do not do this.
• Mulch. Two to four inches across the root zone, held back from the trunk. Mulch also keeps mowers and trimmers away from the bark, which removes one of the most common entry wounds we see.
• Soil health. Soil conditioning and appropriate nutrition give roots the environment they need to regenerate.
• Protect trunks on young and thin barked trees from western sun exposure, which creates the scalded tissue flatheaded borers favor.
• Right tree, right place. When you plant, favor species suited to North Texas heat and clay. Our guide to drought tolerant trees for Dallas landscapes is a good starting point.
• A plant health care program. Regular professional tree health care catches decline early, when the response is inexpensive.

Wes Rivers, TreeNewal’s owner, says it plainly: it is easier to keep healthy trees healthy than to save them when they are declining. Borers are one of the clearest illustrations of that principle in practice.

Frequently Asked Questions

Can a tree survive a borer infestation?

Many trees do, particularly when the infestation is caught early, the species is not a specialist killer, and the underlying stress is corrected. Ash trees infested with emerald ash borer are the difficult case, because that insect is highly efficient and untreated ash typically decline quickly. Prognosis depends on the borer species, how much of the cambium has been damaged, and the tree’s overall vigor, which is what an arborist evaluates on site.

When is the best time to treat for borers in North Texas?

Trunk injections can be applied any time borer activity is diagnosed, and they work quickly, so there is no need to wait for a particular season once borers are found. Preventive bark sprays are timed to adult flight periods that vary by species. Fall and winter are also a good time for an assessment and for soil and root work, so problems are caught early rather than after the damage is visible.

I see sawdust at the base of my tree. Is that always borers?

Not always. Carpenter ants, wood decay, and normal bark shedding can all produce debris that looks similar. The texture and location tell the story: fine granular frass pushed out of small round holes suggests borers, while coarse fibrous material often points to ants or decay. A photograph of the material and the hole pattern is usually enough for us to give you a preliminary read.

Does removing an infested tree protect the rest of my yard?

Sometimes, and it is one tool among several. Removal eliminates breeding material for species that colonize dying wood, and for regulated pests it also matters how the wood is handled and disposed of afterward. The more durable protection is raising the vigor of the surrounding trees so they are not attractive hosts in the first place.

Look Now, While Looking Still Helps

Borer damage is slow, quiet, and cumulative, and the window in which intervention changes the outcome is early. Trees that carried this summer’s drought are the ones to inspect first.

TreeNewal’s ISA Certified Arborists can identify what is boring into your trees, evaluate how far it has gone, and put together a treatment and plant health care plan built around your property. Contact us today to schedule an inspection.