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NASHVILLE, Tenn. (WKRN) – The Emerald Ash Borer was discovered in Tennessee in the Knoxville area in 2010. 12 years later, the invasive species has spread from East to West, killing ash trees in its path.

For several years the state put quarantines in place to restrict the movement of materials like logs, firewood, and nursery stock, that could carry the bugs or larvae. But, it was no use.

“The white flag has been thrown up,” explained Tim Phelps, Tennessee Department of Agriculture, Division of Forestry Public Information Officer. The Emerald Ash Borer is here to stay. And, there are things that homeowners need to know about how to protect, if they want to protect a tree, as well as landowners.”

Phelps continued to explain how the bug destroys the trees and what can be done about it.

The bugs are beetle-like and metallic green growing to about a half inch long.

“They land on the tree, and basically, enter the tree, and they lay their eggs. Then in the fall those eggs hatch, and we have the larvae. This is actually what does that damage on this new tissue.”

Emerald Ash Borer and larvae

He continued, “It’s kind of a serpentine style eating or feeding pattern that these larvae do inside the trunk of the tree. That in and of itself weakens the tree. But, ultimately what these larvae do is completely encircle the stem of the tree or a branch.”

Phelps said another sign of the invasive bug is a D-shaped hole. “Once that larvae on the inside of the tree matures into that adult form, the adult emerges from this D-shaped exit hole.”

D-shaped exit hole from Emerald Ash Borer

The tree will die from the top down. They call that “dieback”.

If you have a younger ash tree that has a trunk less than the width of a basketball, and it only has a little dieback at the top, you can treat it yourself with a chemical that can be purchased at most garden shops called Imidacloprid.

“You basically dig down and dig a line around the bare mineral soil around the base of that tree and drench your solution all the way around it,” Phelps said.

The insecticide will then be absorbed by the roots into the rest of the tree, killing the larvae.

For larger trees, Phelps suggested you contact a certified arborist who has more tools at their disposal.

In the future, there is hope for genetically modifying ash trees to make them resistant to the insect.

In Michigan, in areas where there has been a large infestation of ash borers, they have had success in weakening one tree. This causes the bugs to populate to that weakened tree, and then, officials simply remove it.

There may still be some hope in the future that will take a lot of work. Unfortunately, it may be impractical for large forests.