Emerald Ash Borer: Death Sentence For Your Tree

Emerald Ash Borer

If you have an ash tree you may have noticed small green flying insects attacking your tree. This insect is called the Emerald Ash Borer and has been labeled the most destructive pest in America. Most of the Emerald Ash Borer’s lifespan is spent in the larva stage where they feed on your trees. However, this is the time of year that adult borers emerge from your Ash trees to mate.

Right now and for the next few weeks you will see these insects flying around and laying their eggs on ash trees. After about 2 weeks the eggs will hatch and the larva will bore their way through the bark and into the cambial region of the tree.  This is where the Emerald Ash Borer becomes deadly. Once in the cambial region, this insect begins to feed on trees’ phloem, a thin layer of tissues that conducts sugars and nutrients throughout the tree. After a certain amount of the phloem has been destroyed it is impossible for the tree to get the nutrients it needs to keep living.  If you have an ash tree don’t give up all hope just yet, read on to learn more about a way to  protect your tree from Emerald Ash Borers.


The Emerald Ash Borer (EAB) is considered the most destructive urban forest pest ever seen in North America. Introduced to Michigan from China sometime in the 1990’s, it is responsible for killing more than 50 million ash trees in over 20 states. Once infested ash trees have a 99% mortality rate if not treated. Luckily a treatment has been recently developed to save ash trees affected by the Emerald Ash Borer; however, ash trees that have already suffered more than 50% dieback are unlikely to survive even with treatment

About The Treatment:

  • 1 treatment provides protection for 2 years
  • Treatment applied through soil injection or trunk injection (depends on your tree’s location).
  • Safe for the tree, humans, animals, and the general surrounding environment including other trees and plants.

Why Is Emerald Ash Borer Protection Important?

  • EAB is an invasive pest that has already killed over 50 Million Ash trees in 20+ states.
  • Once your Ash tree is infested with Emerald Ash Borers it has a 99% mortality rate. 
  • Prevention is key: once you see the signs the tree has most likely been infested for years.
  • Ash trees are home to over 43 different species which will be adversely affected if your ash tree dies.

Emerald Ash Borer Map

Emerald Ash Borer has spread to over 20 states.

Without treatment your tree has a 99% mortality rate.

Without treatment, your tree has a 99% mortality rate.

Emerald Ash Borer Signs & Symptoms:

  • Canopy dieback, beginning at the top and progressing downward.
  • In later stages, ash trees may form sprouts from the trunk and roots.
  • Increased woodpecker activity.
  • The tree’s bark can split, exposing “S”- shaped galleries underneath.
  • “D” Shaped exit holes in the tree’s bark about 1/8 inch in diameter.

“S”-Shaped Galleries

“S” Shaped Galleries

emerald ash borer

Woodpecker Activity On An Ash Tree

sick tree entry and exit holes

“D” Shaped Exit Holes

Frequently Asked EAB Questions

How Do I Know If My Tree Is Infested?

First, determine if your tree is an Ash tree by using our Ash Tree ID Guide. Once you know your tree is an Ash tree look for the Common Signs and Symptoms of Emerald Ash Borers.

Can My Ash Recover On Its Own?

No, once infested ash trees will die if not treated.

I’ve Treated My Trees In The Past For Borers. Are They Safe? 

No, there are many different types of borers that range in severity and each treatment is unique to the type of borer. Emerald Ash Borers are highly invasive and kill trees rapidly. In order to prevent them, specific treatment is needed.

Is It Better To Treat Or Remove My Ash Trees? 

Treatment is typically better than removal for a couple reasons.

  • First, it is the cheaper option. It is 4 times more expensive to remove a tree than to treat it, and 10 times more expensive to remove and replace the tree.
  • Secondly, ash trees are home to 43 different species which will be adversely affected if you remove your ash trees.
  • Lastly, mature trees add to home values. Removing your ash trees will decrease the value of your property.

However, not all ash trees are good candidates for treatment. As a common rule of thumb if 30% or more of the tree’s canopy has declined or died back the tree can not be saved by treatment and should be removed as soon as possible. An Emerald Ash Borer infestation weakens the structure of Ash trees which makes them more likely to fall and cause property damage. These trees are likely to be dangerous to remove and should be taken down by experience professionals using techniques other than climbing and tying into trees.

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