Emerald Ash Borer




What is the emerald ash borer?

The emerald ash borer is a non-native, invasive insect that was first identified in Ontario in 2002. Since then, the insect has spread eastward across Ontario - killing millions of different types of ash trees. It was first found in south Whitby in 2011 and in Brooklin in 2014.

The early infestation of emerald ash borer is difficult to detect. The pest can be active for three to four years before any signs or symptoms are noticeable. However, bark damage left by woodpeckers feeding on larvae is one way to indicate there is serious infestation of the emerald ash borer.

What is the Town's role?

The Town of Whitby is responsible for treating or removing and replacing ash trees located on Town roads, parks, open spaces, woodlots and other municipally owned properties.

Treating ash trees


Ash trees affected by the emerald ash borer can be treated with the pesticide TreeAzin. Significant, healthy and structurally sound trees with less than 30 per cent canopy loss are the best candidates for treatment. Ash trees must be treated once every two years for about 15 years or until the threat of an emerald ash borer infestation has passed.

The life expectancy is generally longer for park trees than street trees because of location and soil differences. Therefore, the Town's efforts to save ash trees focus on trees located in parks. About 250 ash trees in various parks are being treated. 

Parks where ash trees are being treated are Heydenshore Park, Lion's Promenade, Windsor Bay Park, Lupin Park, Waterfront Trail from the Whitby Marina to Gordon Street, Iroquois Park Arena, D'Hillier Park, Brooklin Optimist Park, Selkirk Park, Whitby Kinsmen Park, Carson Park and Spencer Community Centre.

Untreated ash trees will become infested with emerald ash borer and will die within one to two years after symptoms are present.

Removing and Replacing ash trees

The Town is continuing its emerald ash borer action plan and has scheduled the removal and replacemnt of ash trees in parks for 2018 and 2019.  Various types of trees will be planted to ensure a diversity of species.

The replacement of ash trees located on boulevards was completed in 2017.

What's the role of property owners?

Property owners are responsible for maintaining, treating and removing ash trees (and any other trees) located on their property.