Modern Mississauga presents Ask The City - Why is the City conducting an aerial spray this spring?

Modern Mississauga and the City of Mississauga have come together to present an ongoing series called “Ask the City.”
We’ll share relevant information and answer your questions about our city.
Today’s question is about the upcoming aerial spray in Mississauga this spring. 

Why is the City conducting an aerial spray this spring?


The City is conducting an aerial spray to lower fall cankerworm and gypsy moth caterpillar populations and prevent tree loss. These caterpillars feed on leaves causing extensive damage and weakening of trees over time. Trees then become more vulnerable to diseases.

The aerial spray area consists of private and public land in Wards 1, 2, 6, 7, 8 and 11. The spray is roughly 1,940 hectares (4,794 acres). The spray is scheduled for April 23 to June 10, between 5 and 7:30 a.m.

Bad weather or wind may cause the aerial spray to be postponed with little-advanced notice. The City will issue a communication to the residents 48 hours before each treatment and provide up-to-date information through 3-1-1 and online at The spray may be cancelled up to 12 hours in advance if the weather conditions change.

A pesticide containing bacillus thuringiensis subspecies kurstaki (Btk), a naturally occurring bacterium found in soil, is the active ingredient that will be sprayed. Btk has been approved by the Pest Management Regulatory Agency, an agency of Health Canada for aerial use over urban areas. The public is unlikely to experience any health effects by the use of Btk.

For more information about the aerial spray, visit or call 3-1-1.

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Please send your questions to with “Ask The City” in the subject line.