City of Hamilton City of Hamilton
Submit SearchSubmit Search
City of Hamilton – Public Works

Emerald Ash Borer


Emerald Ash Borer Q&As 

The Emerald Ash Borer (EAB) has been detected throughout the City of Hamilton. Visit this page for up-to-date information on the management of the emerald ash borer in the city.

What is the Emerald Ash Borer (EAB)?

The emerald ash borer is a highly destructive invasive beetle that infests ash trees. It has killed millions ash trees in North America and poses a major environmental threat to urban and forested areas across Hamilton.  EAB has the potential to destroy Hamilton’s entire ash tree population over the next 10 years.

What does the emerald ash borer look like?

The beetle is metallic green in colour and is 8.5 to 14.0 millimetres long (about ½ inch) and 3.1 to 3.4 millimetres wide (1/8 inch). The back of the insect is an iridescent, metallic green, the underside is a bright emerald green. The body is narrow and elongated, and the head is flat. The eyes are kidney shaped and usually black.

Adult Ash Borer Beetle 
Photograph courtesy David Cappaert, Michigan State University

What does the emerald ash borer do?

The adult beetles lay eggs on the bark of ash trees and the eggs hatch into larvae. The larvae are white and flat, have distinctive bell shaped segments and can grow up to 3 centimetres long.

Ash Borer Larva

The larvae cause significant damage by boring tunnels, or galleries, just under the bark in the layer that is responsible for transporting water and nutrients throughout the tree. With this layer damaged, the ash tree will  die within a couple of years. It is anticipated that EAB will kill most of the ash tree population in the Hamilton area.

Where did the emerald ash borer come from? How did it get to Hamilton? How long has it been here?

The emerald ash borer is native to China and eastern Asia. It was first discovered in North America in 2002. In May 2002, it was discovered in southeastern Michigan in the United States and in July 2002 it was found in Essex County (Windsor) in Ontario.

Like some other exotic pests that affect plants and trees, it is believed to have been accidentally introduced to North America in imported wood packaging or crating materials.

How is the Emerald Ash Borer spread?

The most common way for the emerald ash borer to spread is through people moving infested materials such as firewood, logs, branches, nursery stock, chips or other ash wood. The emerald ash borer also spreads naturally through beetle flight. Research indicates the adult can fly up to 10 kilometres, but generally does not stray from the immediate area upon emergence.

What types of trees are at risk?

The emerald ash borer is known to attack all North American species of ash trees within the genus Fraxinus. It does not attack mountain ash trees (genus Sorbus).

What is the importance of ash trees?

Ash trees are an important part of Hamilton's urban and rural landscape. They are commonly found on city streets, in woodlots, in windbreaks and in forests.

Ash wood is used to make furniture, hardwood floors, baseball bats, tool handles, electric guitars, hockey sticks, and other materials that require high strength and resilience.

How do I know if I have an ash tree?

An ash tree typically has:

Opposite branching: their leaves and twigs are in opposite positions on the stem. They are not staggered.

Ash Tree - Opposing Branching
Photograph courtesy of Eli Sagor, Minnesota, USA

Compound leaves: leaves that have more than one leaflet, while the entire leaf has one bud at its stem base. The leaflets are positioned opposite with one at the top. Ash trees typically have 5-9 leaflets per leaf.

Ash Tree - Opposing Leaves
Photograph courtesy of Rob Routledge, Sault College,

Rigid bark with diamond-shaped ridges (on a mature tree).

Rigid bark with diamond-shpaed ridges
Photograph courtesy Paul Wray, Iowa State University,

Seeds that hang in clusters and are dry and oar-shaped.

Dry, oar-shaped seeds
Photograph courtesy of Keith Kanoti, Maine Forest Service,

What are the signs of Emerald Ash Borer infestation?

Signs of emerald ash borer infestation usually become apparent once a tree has been heavily infested. These signs include:

The loss of green colour in the uppermost leaves

Thinning and dieback of the crown (when branches start to die from the top of the tree down) 

Thinning and crown dieback

Photograph courtesy Ches Caister, CFIA staff

    Leafy sprouts – called epicormic shoots – grow from the roots, trunk or branches to find new ways to transport nutrients

    Leafy sprouts and shoots

    Photograph courtesy Joseph O'Brien, USDA Forest Service,

      Increased woodpecker activity

      S-shaped tunnels, or galleries, just under the bark

      S-shaped tunnels or galleries

        D-shaped exit holes in the bark

        D-shaped exit holes

                       Photograph courtesy Jeff Dowding, Canadian Food Inspection Agency

        Does the emerald ash borer pose a threat to humans or animals?

        No. The emerald ash borer does not pose a direct threat to humans or animals.

        How does the emerald ash borer kill ash trees?

        Emerald ash borer larvae feed underneath the bark and block nutrients and water from moving throughout the tree. The tree may be killed within a few years of the initial infestation.

        Can the emerald ash borer be completely removed from a tree?

        No. The emerald ash borer cannot be completely removed. To help control the spread, the Canadian Food Inspection Agency (CFIA) has placed restrictions on the movement of all firewood and ash tree materials in Hamilton and other affected areas. EAB is generally spread through the movement of firewood, nursery stock, and forest products.

        What is the City of Hamilton doing about the emerald ash borer?

        EAB has the potential to destroy Hamilton’s entire ash tree population of approximately 23,000 trees in the next 10 years. City council approved a proactive plan to remove 10% of Hamilton’s ash tree population each year for the next 10 years. Each ash tree that is removed will be replaced with a new species of  tree to help diversify Hamilton's urban forest.

        Will the City of Hamilton remove infested ash trees from my property?

        The City of Hamilton will remove infested ash trees from your property if it is located within the road allowance. You are responsible to remove ash trees that are not located within the road allowance. The road allowance varies throughout the city. Call 905-546-2489 to have someone come to your house and determine if your ash tree(s) is located on the road allowance.

        My ash tree is on the City’s road allowance. What should I do?

        If the tree in your front yard is showing signs of being infested with the emerald ash borer, call 905-546-CITY (2489) to have your tree assessed. A replacement tree will be planted once the infested tree and stump is removed.

        My ash tree is not on the City’s road allowance. What should I do?

        You are responsible for all trees that are not on the City’s road allowance. This includes the treatment, removal and disposal of dying or dead  ash trees. Contact a certified arborist to discuss your options.

        Should I treat or remove the ash tree on my portion of my property?

        This is an individual decision. If you choose to treat, rather than remove, your ash tree, the treatment must be performed once every two years to be effective.

        How do I have an ash tree on my property treated?

        You should contact a certified arborist for treatment options.

        How do I dispose of my infested ash tree?

        When you have a certified arborist remove your tree, they will know how to properly dispose of the infested tree. Do not allow an arborist to leave the infested tree, or parts of the tree, on your property.

        For more information contact the Canadian Food Inspection Agency at 1-866-463-6017 for proper disposal instructions.

        What is an arborist?

        An arborist is a trained in the science of planting, caring for, and maintaining trees. An arborist will offer most tree care services such as:

        Tree health assessment (pests and disease)

        Pesticide treatment

        Tree planting

        Tree removal

        Tree stumping

        Proper disposal of infested trees

        Why should I hire an arborist?

        Arborists are trained and equipped to provide proper tree care, including pruning, removal, and stumping. Pruning, removing, or stumping trees without the proper training can cause significant injury or damage to yourself or your property.

        How do I find an arborist?

        There are several places to find a certified arborist in the Hamilton area. Look in your phonebook under “tree care” or go online and visit web pages such as or

        Is the City treating or removing its ash trees?

        The City is using pesticide injections on 800 selected high value ash trees. In order to be effective, these trees will be treated every two years. Treating all City-owned ash trees is not economically feasible.

        Where can I get more information on  EAB?

        Visit the Canadian Food Inspection Agency’s (CFIA) website at:

        Or call CFIA directly at: 1-866-463-6017.

        Additionally, there are many sources of EAB information on the Internet.