Everything you need to know about the Emerald Ash Borer: Part 1

 Many of you have probably heard about the decline of the ash tree throughout North America, but what exactly is causing this massacre? The answer is the invasive Emerald Ash Borer, or EAB. Descendants of Asia, these metallic green half-inch beetles lay their eggs on the ash trees and the larvae feed under the bark, causing the tree to slowly die off. First discovered in Michigan in 2002, the EAB has rapidly made its way throughout much of the Northeastern United States. By educating the public about this invader, there are hopes it will help slow down the spread of EABs.

Here’s how you can help!

First: Identify that you have an ash tree in your yard. Ash trees have opposite branching, with one branch being directly across from another on the same limb.

They also have compound leaves, with 5-11 small leaflets with a terminal leaflet pointing outwards at the end.


Additionally, they have a bark pattern that looks like diamonds or ‘X’ shapes.

Lastly, sometimes ash flower galls develop on the branches that are black or brown clustered balls of flowers left from spring that are seen in winter.

Ash Flower Gall - 1

There are also many different species of ashes, so they may not all look the same. Ones most affected by the Emerald Ash Borer include: The White Ash, Fraxinus americana, a popular ornamental tree, as well as a common choice for building furniture or tools with; Black Ash, Fraxinus nigra, commonly used by Native Americans for basket making; Fraxinus pensylvanica, the Green Ash, another popular ornamental tree; and lastly, the Blue Ash, Fraxinus quardarngulata, most often found on elevations.

Second: Identify that your ash tree is infected. Symptoms of an EAB-infested ash tree include a thinning or dying canopy top, new branch sprouts from the base of the tree, or D-shaped holes where the adult beetles emerged.

Signature "D" shaped holes where the adult EAB emerge.

Also, woodpeckers like to feed on the EAB, so signs of woodpecker holes could also potentially mean an invasion. It’s important to note that although a tree may not look infested, it is highly likely that they are. Looking for those key signs such as loosing leaves on top or D-shaped holes in the bark are key to preventing further damage. The sooner an invasion has been identified then the sooner action can be taken to save the tree.

Third: Take action. It’s either time to protect the tree by using insecticides or you cut it down. There are many insecticide options out there, and your municipality may have already treated your ash tree. Contact them first to see if your tree has received any treatments.

If it hasn’t, or your tree is on private property, then the Morton Arboretum has compiled a list of all the ways your ash tree can be treated. Click here to view these. They include soil injections, trunk injections, and trunk sprays, among others. Some treatments can be found at a local hardware store, but some are only available through a professional. It is recommended that if 30% or more of the canopy has died, it is better to remove the tree than try to protect it. The chances of a healthy comeback are slim, and keeping the tree only serves as a home for more EABs in the neighborhood. Although you can’t put up another ash tree, there are many other suitable trees that can replace it. The Morton Arboretums website can help you choose which trees are most compatible for your area.

As a homeowner, it may not concern you that one of your trees is dying. “So what? It’s just a tree,” you might be saying. However, that “tree” multiplied by millions is what the Emerald Ash Borer has killed. It is estimated that they have caused over $10 million in damage. Since they can infest ash trees as small as ones with diameters of 2.5 cm, nearly every ash tree, sapling, and seedling is at risk. If we can’t stop them now, a nationwide extinction of ash trees is the consequence we are facing.

But why is this damage so devastating?

a) For one, the North American ash trees and the EAB do not share a past, which means that the EAB has an easier time taking over because the ash trees here in the U.S. are defenseless. The ash trees in Asia have evolved defenses against this beetle because they have both coexisted for hundreds of years. However, the ash trees in North America have never been exposed to the Emerald Ash Borer, so they don’t know what to do.

b) Emergence of ash tree seedlings could give EABs an excuse to hang around and continue attacking the ash trees and cause a complete extinction in some areas. Since it takes 60 years for an ash tree to reach reproductive maturity, it makes gathering seeds hard to do.

Screen Shot 2013-07-25 at 9.30.19 AM

c) Movement of firewood from one place to another is also responsible for the transfer of EABs. Infested ash firewood that gets moved across states creates a risk of a new outbreak of EABs. As a result, Illinois is now federally regulated in firewood distribution, along with many other already infested states. Remember to always purchase local firewood, burn it before moving to another area, and resist hauling it long distances.

d) Ash trees planted too close together make for an easy pathway for the Emerald Ash Borer to follow from tree to tree. Without enough diversity, an infestation is a most definite. This is the case for many cities where they planted only ash trees along the streets or for forests containing large amounts of ash trees.


By working together, we can all help save the beloved ash trees! Every person makes a difference in the survival of these magnificent trees.  Author: Melissa Nelson,  The Conservation Foundation’s 2013 Summer Intern & Biology Student at North Central College

All materials and information gathered are from these lists of websites:

To check out insecticide options:


To read about the ecological impacts of EABs (detailed) Wendy Sue Klooster (2012):

http://etd.ohiolink.edu/send-pdf.cgi/Klooster Wendy S.pdf?osu1338337754

To learn more about ecological impacts (simplified):


To identify your ash tree:


To check firewood movement regulations in your state:


To read more about biological control updates:


To read more about the Forest Health Technology Enterprise Team and their studies:


To read about what the USDA is researching about the Emerald Ash Borer:


To read about the Illinois Department of Agriculture research about the EAB:


To read about general information on the Emerald Ash Borer:


To read a scientific journal entry about the EAB:


Pictures were taken from Google.

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