A city news release says helicopters will distribute the pesticide just above the tree line, which will result in the closure of some roads, beaches and golf courses.
The spraying is scheduled to take place from May 21 to June 11 from 5 a.m. to 7:30 a.m.
At the caterpillar stage, the insect eats the leaves of trees, making them more susceptible to disease. Using pesticides will help preserve local trees and help control the European Gypsy Moth population, a City of Toronto News release.
The aerial pesticide bacillus thuringiensis subspecies kurstaki (BTK) will be used. The city says it is not harmful to humans or animals. It contains naturally occurring bacterium found on dead or decaying matter in the soil. In order for the spray to work, caterpillars must eat BTK-treated leaves.
This method of moth outbreak control was last used by the city in 2008.