The 101 on Emerald Ash Borer

Emerald ash borer (EAB) is one small pest that has caused a lot of damage.

Since the insect was first discovered in the USA in 2002, our Davey Institute scientists have been researching the best way to control emerald ash borer.

Our goal has always been to save your ash trees! After all, with EAB, the stakes are high. Comprise as much as 35 percent of suburban tree canopies, there are a whopping 7 billion ash trees in the USA that are susceptible. 

EAB infestation was once thought to be a death sentence for your ash trees. Now, we know it’s not.

Read on to learn the newest, latest information about this damaging pest and raise awareness about emerald ash borer.

What Is Emerald Ash Borer?

Emerald ash borer is an invasive, wood-boring beetle from Asia that has been eating our nation’s ash trees since 2002. The insect itself is emerald in color and is tiny – 1/2 inch in length and 1/8 inch wide.

The emerald ash borer may be small, but the devastation this pest has caused is enormous.

Emerald ash borer has destroyed tens of millions of ash trees in 36 states as of January 2021. Through treatment, removal, and tree replacement, the emerald as borer has cost billions of dollars.

Once in your region, emerald ash borer will “ultimately kill all unprotected native ash trees” over the next 5 to 10 years said Colorado State University’s Whitney Cranshaw.

What is The Life Cycle of the Emerald Ash Borer?

In mid-May, just as the black locust trees bloom, the adult emerald ash borer emerges from inside the tree and flies through September. The rest of the year, the larvae are developing beneath the bark.

And, that’s when emerald ash borer wreaks havoc.

The beetles lay eggs in the trunk of ash trees. The larvae then begin eating inside the inner bark. In turn, this destroys the tree vascular tissue that carries water and nutrients through the tree.

Where Is Emerald Ash Borer?

As of July 2021, emerald ash borer has been detected in 35 states and the District of Columbia.

See the most recent emerald ash borer map from the USDA above. The map is often updated, so check back for recent additions.

How Can I Control Emerald Ash Borer?

Once emerald ash borer is in your area, take action. Have your local, certified arborist inspect your trees for risk. Did we mention we offer a free emerald ash borer consultation?

Preventative and/or early treatment of EAB is the only way to maintain your ash trees when this pest has established in your area. 

How to Protect Ash Trees from Emerald Ash Borer

At Davey, we recently discovered a new way to detect emerald ash borer during the first year. That’s an entire year earlier than previously possible. When you spot EAB earlier, you can seek early treatment, which is more effective.

Look for these early symptoms of emerald ash borer:

• Thinning of the canopy and more branch breakage at the top of the tree
• Visible cracks on the tree’s lowest Southwest branches
• Branches that break close to the trunk

Later on, look for these more pronounced symptoms of emerald ash borer:

• Excessive woodpecker activity and damage
• Chewing damage on foliage edges
• Thin, 2 to 5 inch vertical slits in the bark
• D-shaped holes in the bark (~3 mm)
• S-shaped tunnels beneath the bark
• Multiple trunk sprouts with a heavy infestation
• Leaf wilt and branch dieback with heavy infestation

Is There Any Prevention for Emerald Ash Borer? How Can I Treat Emerald Ash Borer?

Yes, there are four types of EAB treatment options. Before they’re applied, your local arborist first needs to determine if your tree is a good candidate for preservation.

When applied correctly, EAB treatment is effective 85 to 95 percent of the time.

For example, when EAB was found in Naperville, Illinois, they chose to immediately treat their trees. Three years later, more than 90 percent of the treated ash trees show no signs of infestation. In communities, such as Naperville, tree inventories can save time and money.

Contact your local arborist to schedule a complimentary EAB inspection for your ash trees.