June 4, 2013
What is the emerald ash borer (EAB)?

The emerald ash borer is an introduced insect pest from Asia that feeds on and kills ash trees. These insects cut off the flow of water and nutrients within the trees by feeding underneath the bark. All species and sizes of ash trees (genus: Fraxinus) are susceptible, except for the mountain ash (Sorbus spp.) which is not a true ash. If a tree has become infested with EAB, mortality will result, usually within 2-3 years.

In North America, the beetle was initially discovered in Michigan and southwest Ontario in 2002, and the first infestations in the City of Toronto were detected in 2007 and in York Region in 2008. It is estimated that the City of Toronto will lose nearly all of its 860,000 ash trees to EAB by 2017 — a number which represents 8.4 per cent of canopy cover over both public and private land in the urban forest.

In York Region, it is anticipated that most of the estimated 2,800,000 mature ash trees growing in the area (700,000 of which are found in the urban forest, and 2,100,000 in rural woodlands) will become infested and die within the next ten to fifteen years. 

How do I know if I have an ash tree in my yard?

The following easy-to-use resources will help you to determine whether or not you have any ash trees on your property:
Ash tree identification guide (provided by the City of London)
Ash tree identification video from emerald ash borer Info website

Crown dieback

Bark split


Exit holes


Above photos courtesy of Michigan State University,
Forestry Images
How do I know if my ash tree is infested?

It is very difficult to detect the presence of EAB in the early stages, as many of the more outwardly visible signs and symptoms appear only after two or more years of infestation. This visual guide shows pictures of the emerald ash borer at various life stages, as well as various indicators of its presence and ash trees in various stages of decline.

*Please note that other insects, diseases, and problems can demonstrate similar signs and symptoms as those depicted in this guide, and thus is it advisable that you contact a certified arborist to confirm whether or not EAB is present in your tree.

What are my options?

If you have an ash tree in your yard or on the city owned property in front of your home, you should learn about your options before taking any action. Visiting the website of your municipal and/or regional forestry departments will inform you of any programs that exist surrounding the control of EAB, and will indicate what measures are in place regarding trees planted on publicly owned land, including boulevard trees.

If your tree appears to be healthy…TREATMENT

While infested ash trees will succumb to the pest, healthy ash trees that are not yet infested or in the very early stages of infestation, can be treated. Currently TreeAzin, derived from the neem tree, is the only product registered for use in Canada against EAB. It is injected into the tree near the base and must be done by a licensed applicator. If your ash tree appears healthy, consider treatment with TreeAzin injections. You can learn more about TreeAzin or find licensed applicator in your area here.

If you live in Toronto and have an ash tree on the city-owned property in front of your home, you are allowed to treat it at your own cost.

If you live in another municipality, check with your local forestry department for details.

If your tree is infested…REMOVAL

If you decide to remove a tree on private property, you will have to incur the cost yourself. There may be removal permits required — check with your municipality. We recommend hiring an arborist certified by the International Society of Arboriculture for any tree work. For a list of certified arborists in your area, visit www.isaontario.com or call 1-888-463-2316.

In many municipalities, infested trees that are located on the city-owned property in front of homes will be removed by municipal/regional forestry staff and replaced at no cost to homeowners.


We encourage everyone who has space to plant new trees to replace those that have been or will be lost to EAB. Even if you haven't personally lost a tree to EAB, planting new trees can help maintain the overall urban forest canopy.

Alternatives to ash

Landscape Ontario Growers' Group, in partnership with the Agricultural Adaptation Council have produced a series of fact sheets on over two dozen trees that can be planted as an alternative to ash trees. For a complete details on each tree, visit http://www.landscapeontario.com/trees-for-urban-landscapes

For more resources and information, and to become an EAB Ambassador, visit www.yourleaf.org/emerald-ash-borer

Information courtesy: Local Enhancement & Appreciation of Forests (LEAF), visit www.yourleaf.org

Check out our handy fact sheets at Trees for Urban Landscapes as a guide for choosing the right tree when replanting or adding to your landscape.