Invasive beetle now in McLennan County could doom local ash trees

The emerald ash borer beetle, an invasive species that has killed millions of ash trees in the Midwest, was confirmed in McLennan County in early May, the Texas A&M Forest Service confirmed.

The beetle is infesting and killing ash trees in new areas of Texas and continues to spread south, leading state officials to ban moving ash wood out of McLennan and other affected counties.

Ash borers can infest and kill both healthy and unhealthy trees of all types of ash, the forest service said.

“(Ash trees) have no natural resistance to the invasive insect,” Allen Smith, a regional forest health coordinator with the forest service, said in the statement. “Without proper proactive measures, mortality can be 100% in heavily infested areas — so early detection could improve our chances to manage for the pest.”

This beetle came to U.S. from northeast Asia and was first documented in Michigan, said Bradley Kuehn, an urban forester and certified arborist with the city of Waco.

The beetle threatens native Texas ash species in wild places such as Cameron Park, as well as Arizona ash trees that were widely planted in suburban neighborhoods decades ago because they were fast-growing and hardy.

Ash trees represent an estimated 4% to 5% of trees in Waco and surrounding cities, said Hector Marines, a state forest service urban forester in McGregor who serves McLennan and surrounding counties. Statewide in rural areas, forests are about 5% ash, he said.

In Waco and McLennan County wooded areas from 5% to 10% of trees may be ash, Joseph White, a Baylor University biology professor, said in a Thursday email.

If the emerald ash borer succeeds in destroying the ash trees in McLennan County the way it did in Michigan, then products made from ash wood and the good ash trees do for the environment will have to be replaced by other trees.

To detect an infestation of ash borers, homeowners and landowners can look for woodpecker or bird damage, or branching and sprouting at the base of the tree.

“If you notice something wrong with your ash tree, see a lot of dieback, call your local arborist or the Texas A&M Forest Service to check it and confirm EAB,” Marines said.

When the adult ash borer enters the tree it makes a D-shaped hole, which may also look like a smiley face, depending on the orientation of the hole, Marines said. Beneath the bark, larvae will create S-shaped pathways as they devour the parts of the tree that move nutrients and help it grow, he said.

Marines recommends that landowners remove and burn infested trees.

“If we’re proactive we can stop the spread,” Marines said. “Burn, chip or bury the infested tree immediately after removal. Look for signs.”

Don’t wait and don’t transport ash wood off the property where infestation is identified, he said.

Local foresters say healthy trees may take three to five years to show signs of infestations, while stressed trees may show borer damage within a year or two. Many trees in this area are stressed after the 2021 extreme winter freeze and the prolonged drought in 2022 and 2023, they said.

If 70% of the crown of an ash tree remains, a landowner can inject a pesticide or insecticide to kill the larvae, though the injections are expensive and must be repeated every two or three years, Marines said.

Kuehn, the city forester, said the injections may be worth it to some.

“If you have an infested ash tree that you really love and want to save it, you call your local arborist and they will be able to get the pesticide or insecticide and inject it,” Kuehn said.

Now that the ash borers are in McLennan County, the Texas Department of Agriculture will quarantine ash wood products, preventing it from being transported from the county.

The borer beetles were first confirmed in East Texas in 2016, and steadily made their way to the Dallas-Fort Worth metroplex, forest service officials said.

Traps set by the forest service confirmed ash borer had moved into Grayson, Hood, and Palo Pinto counties adjacent to the DFW area, according to the statement. They were also confirmed in Hill and McLennan counties, skipping over several counties between the other infested region.

“It’s more likely for EAB to spread to adjacent counties, but the spread to McLennan County indicates that EAB is being spread by humans, which can be prevented,” Smith said.

The insects have a lifespan in the adult phase of about three weeks, Kuehn said. In that time they won’t fly more than a mile or two.

The adult ash borers are active from around April to June in Texas, Marines said. The rest of the year larvae eat the trees from the inside.

Texas ash and green ash trees are typically found closer to streams and stream bottoms though can live in uplands, said White, the Baylor biologist. In McLennan County, most ash trees grow in ribbons of vegetation along stream banks.

These trees produce small seeds that are the right size for many medium song birds, ducks and rodents. Also, their thin leaves decompose rapidly, releasing nutrients back to the soil more quickly than junipers and oaks.

“With their loss, there will be a deficit in native seeds available for birds and other smaller animals,” White said. “There will also be a composition shift in the woodlands favoring species with less immediate nutrient needs — juniper and oaks.”

Ash trees also help fill in the forest canopy and provide shade for the forest floor, Marines said. And like all trees they provide shade, maintain soils and manage storm runoff as well as purifying air and water.

White ash trees also provide food for some wildlife, such as cardinals, finches and wood ducks, Marines said.

“Ash trees are also important to us because of the products they provide,” Marines said.

The wood of the white ash is pliable and strong, though lightweight, he said. It is used for baseball bats, hockey sticks, guitars, boat oars, flooring and furniture.

The wood of the black ash is not as strong as white ash, but has a grain look that is used for furniture, Marines said. The wood of a young black ash can be split and used for cabinet making.