Emerald Ash Borer (EAB) Advisory

Potentially one of the most destructive alien pests ever introduced in the United States, Emerald Ash Borer (EAB) represents an immense threat to Gurnee’s urban forest.  First discovered in southeastern Michigan in 2002, EAB has rapidly spread across the Midwest, killing millions of ash trees.  The first infestations in Illinois were discovered in rural Kane County in 2006 and moved across Chicagoland afterward.  The Village’s first confirmed infestations were found in the Boulders and Spruce Pointe subdivisions in December 2010.

emerald ash borerEAB will eventually spread throughout the entire Village and kill every ash tree that is not treated or removed. This is particularly troubling due to the large number of ash trees on both public and private property. The Village is currently implementing a plan to respond to this threat and would like to encourage residents to do likewise.  This website has been compiled to help you better understand what EAB is, to help you consider your options in addressing it on your property and to update you on the Village’s actions and responses to this threat.


What is the Emerald Ash Borer?

EAB is a wood-boring beetle from Asia that feeds on ash trees.  Adult beetles are metallic green and about ½ inch long.  Once introduced into an area, the adult beetles lay eggs in ash trees. The larvae bore into the tree and literally strangle it by damaging the tree’s vascular system, or the main circulatory system of the tree. Within two to three years, the tree dies and becomes brittle. If the tree is not removed at this point, it could become a public safety hazard.

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Is my tree an Ash species?

While there are several different ash species, they share some common characteristics. Ash leaves are perhaps the easiest way to identify if a tree is an ash. These leaves will have 5-11 smaller leaflets attached that grow directly across from each other and are either smooth or have very fine "teeth." Aside from these leaves, older ash trees will have a distinctive diamond-shaped bark while younger trees will have a smooth bark surface. Finally, ash trees have dry, oar-shaped seeds that hang in clusters from the tree until falling in late fall. More information on identifying ash trees can be found at http://emeraldashborer.info/files/e2892Ash.pdf.

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What are the signs and symptoms of EAB?

Ash trees infected with EAB will show early signs of woodpecker damage. You may also notice “D” shaped holes in the tree’s trunk where the adult beetle emerges. Later signs of infestation include tree crown dieback and “sprouting” where new sprouts form at the base of the trunk. Please note that EAB only impacts ash trees. 

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Frost Cracks

Woodpecker Damage


Why should I be concerned?

EAB is particularly concerning due to the sheer number of ash trees in the Village.  Ash is native to Illinois and was popular for a number of years as a shade tree for both public parkways and private property.  In addition to the 3,400 known ash trees in Village’s parkways, there are likely thousands more on private property.  If you take no action, the tree will likely die and could cause property damage if not removed.

What can I do to address the problem?

At this time, property owners have two options: outright removal or treatment of their trees.  Certain insecticides have proven to be effective in treating or preventing infestation if the damage to the tree is not too extensive. Contact an International Society of Arboriculture (ISA) certified arborist to see what options you have for treatment. A list of certified arborists can be found at this web address: http://www.isa-arbor.com/faca/findArborist.aspx. Please note that treatment, depending on the insecticide used, may be effective for one or two years and then will need to be reapplied and will be a long-term commitment.  Thus treatment may be more costly than outright removal. Further, if your tree does die, the Village may require you to remove it in order to protect the public.

If you are having a tree removed, make sure that your contractor has signed an EAB compliance agreement with the State of Illinois Department of Agriculture. This agreement outlines how to handle infested wood to slow the spread of EAB.

What is the Village doing to address the threat?

The Village has been fortunate to have the advantage of time.  The Village has diversified the types of trees it plants in the right-of-way or offers through the 50/50 Parkway Tree program.  As part of that diversification, no ash trees have been planted on Village property since 2001.  Further, the Village has been planting new trees in areas of high ash density, which will alleviate the aesthetic damage done in those areas by EAB.

Forestry staff continues to actively scout for and follow-up on all calls about exotic tree pests in our community. With the discovery of an Emerald Ash Borer infestation in Gurnee in early 2011, Public Works crews began an aggressive campaign to determine the boundaries of the infestation and finalize a response plan. This plan includes chemical treatments, proactive removals and replacement planting with diverse tree species.  

Click here to be directed to our tree inventory map to find information on species and treatments.  

Please follow the links below to find out more information about threats to our urban forest. 

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Trees that qualify for treatment
Trees that do not qualify for treatment

Treatable Ash Tree vs. Untreatable Ash Tree

The Village will not inspect trees on private property due to the limited size of staff. Please contact an ISA certified arborist for any questions regarding trees on your private property.

What can I do to help?

EAB is not a naturally fast moving pest (about ½ mile per year) but has been able to spread through the movement of infested firewood.  Please do not move ash firewood.  Further, please ensure that any contractor you hire to remove or treat your tree has signed the EAB Compliance Agreement with the State of Illinois Department of Agriculture, as discussed above.

Further Resources: