emerald ash borer on a leaf

How to Prevent Emerald Ash Borer Infestations

The emerald ash borer (EAB) is notorious for destroying forests of ash trees across much of the United States. Like other borer insects, they dig into tree trunks and feed on the inner layers. Unfortunately, they are also invasive to the US. This makes them even more difficult to control, which is why several states have experienced devastating damage to their ash tree forests since this pest was accidentally introduced in the 90s. EAB has yet to make its way into Utah, so our primary goal is preventing infestations. Read on to learn how to identify and prevent EAB infestations in your trees.

EAB Lifecycle

emerald ash borer
Emerald ash borer adult

EAB are native to parts of Asia and only attack ash trees. Adults are metallic green and about half an inch long. In summer, females lay their eggs in ash tree bark. Once the eggs hatch, EAB larvae bore into the inner layers of the tree and feed inside the tree until they reach adulthood. Eventually, they emerge from the tree (creating D-shaped exit holes) and feed on ash tree foliage as adults.

How EAB Spreads

EAB spreads quickly on its own, but humans have helped widen the reach of EAB. People contribute to the spread of EAB primarily through transporting infested firewood to unaffected areas.

Preventing EAB Infestationsemerald ash borer on a penny, next to eab holes in a tree branch

One of the best ways to prevent EAB from spreading is to keep firewood in the same area where you gather it.

You can also periodically check your ash trees for signs of EAB:

  • Woodpecker damage
  • D-shaped exit holes in the bark
  • Tiny branches growing near the base of the trunk
  • Dead leaves starting at the top of the tree

Checking for infestations can help you identify an infestation in its early stages. It can take 2 or more years for the tree to show obvious signs of an infestation, so if you wait, it may already be too late for your tree.

If you find signs of an EAB infestation, notify the USDA (1-866-322-4512) as soon as possible.

EAB Control Efforts in the US

At first, government agencies attempted to isolate and eradicate EAB from the US, but it spread too quickly because it has no natural predators here. Since then, researchers have introduced several of EAB’s natural predators to heavily infested areas of the US, successfully controlling the EAB population in those areas. While this has helped reduce the rate of damage, EAB is still a problem and will likely continue to be one.

EAB have not been detected in Utah, but they have been found in Colorado, so Utahns should continue to watch for signs of infestations. Though EAB infestations tend to be more serious, other borer insects that are native to the US are also a threat to your trees. Once borer insects have infested a tree, they are very hard to eliminate. This is why the best hope for your tree is borer bug prevention.


Stewarts offers tree services that will help prevent borer insects and other common tree pests from infesting your trees. Call or text our office at 801-226-2261 to talk with one of our ISA-certified arborists! Get a free tree service quote today!