Our Guide to Emerald Ash Borers

Emerald Ash Borer Damage

Of all the tree-destroying insects in Colorado, there is one that is familiar to nearly all gardeners and homeowners—the Emerald Ash Borer. Read our guide to help you figure out if this pest has infested your yard.

What is an Emerald Ash Borer (EAB)?

The emerald ash borer is an invasive insect that was first detected in the United States in 2002 and has since then spread across thirty-five states and killed more than fifty million trees, decimating the US’ ash population. The infestations are continuing to spread throughout the country—and once a forest has become infested, it is expected to lose all of its trees within 10 years.

Other Types of Ash Borers

Aside from the emerald ash borer, which is the most widespread and dangerous of the ash borer family, other common ash borer species include: 

  • Lilac Ash Borer
  • Clearwing Moth
  • Ash Bark Beetle
  • Ambrosia Beetle

How to Identify an Emerald Ash Borer

Emerald ash borer adults are tiny, metallic green beetles, about the size of a grain of rice. But it is the larvae, which are cream-colored worms with bell-shaped segmented bodies, that cause damage to trees. As soon as they emerge from their eggs, they begin to tunnel into the cambial layer of the tree. They wind back and forth carving S-shaped galleries in the wood

Where Are Emerald Ash Borers Active?

Since its discovery, the EAB has spread across 35+ states in the US and counting. Many states and counties have put restrictions on the transportation of firewood in order to mitigate the spread of these deadly insects. 

Where Are Emerald Ash Borers From?

Originally from Asia, the emerald ash borer's native range includes:

  • Russia 
  • Mongolia
  • Japan 
  • China
  • Taiwan

It is unknown how long the pest has been in the country, but the first detention was in southeastern Michigan in 2002. 

When Are Emeral Ash Borers Active?

EAB emerges from under the bark of ash trees beginning in late May or early June and are most active between mid-June and early July. They are visible during sunny, warm days and shelter under bark or foliage when it is rainy or cold. 

How Long Do Emerald Ash Borers Live?

After hatching in 7-10 days, the larvae feed under the bark and go through five instars before they reach adulthood. An adult EAB can live for up to 3 weeks. 

Why Are Emeral Ash Borers Dangerous?

After they hatch, the larvae of the EAB bore into the ash tree and feed under the bark, carving large galleries in the tissues of the tree. This disrupts the tree’s ability to transport water and other nutrients

How Long Does It Take For A Tree to Die?

How long a tree can survive an EAB infestation depends on the population. With high EAB populations, small trees may die within 1-2 years while large trees can be killed in 3-4 years.

What Types of Ash Trees Can Be Infested?

All types of ash trees are susceptible to Emerald Ash Borers, including: 

  • Black Ash
  • Blue Ash
  • California Ash
  • Carolina Ash
  • Green Ash
  • Gregg’s Ash
  • European Ash
  • Manchurian Ash
  • Manna Ashe
  • Narrow-Leaved Ash
  • Pumpkin Ash
  • Velvet Ash
  • White Ash


How Do Emeral Ash Borers Spread?

EAB spreads mostly through infested firewood transported by humans. To prevent the spread, do not transport infected firewood across state or county lines. 

Early Signs of an Emerald Ash Borer Infestation

Early signs of an EAB infestation include canopy thinning and branch dieback that starts at the top of the tree and works its way down. Other signs include:

  • Bark splitting
  • D-shaped exit holes
  • Woodpecker activity
  • Zigzag galleries under the bark

Call The Tree Care Experts At American Turf and Tree Care

Your trees and ornamentals are an important investment in your property. That’s why we have been providing top-notch quality tree care services for over 40 years. We know how valuable your trees are to your property and we will take the best care of them. 

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