Mississauga begins aerial spray to control tree-killing insects

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Published May 11, 2022 at 2:41 pm

The Town of Oakville’s Forestry Section has scheduled the first of two aerial sprays to control LDD moth infestation to take place Monday morning (May 30). INSAUGA PHOTO

Mississauga’s aerial spray program begins early next week in an effort to save the city’s tree canopy.

The spray is meant to control caterpillars that feed off a variety of trees before eventually turning into moths that then begin the cycle again.

Low flying helicopters are scheduled to be out in the early hours of May 15 with the program continuing at various intervals until the middle of June.

Mississauga has deemed the program necessary as the insect (formerly called the gypsy moth caterpillar but now known as the spongy moth or the LDD moth) feeds off leaves which can lead to the killing of trees and at an alarming rate. The spraying is done in the spring with the hope that it will kill larvae and caterpillars before they turn into the moths.

The aerial spray program is expected to protect hardwood trees like maple, oak, elm, ash, poplar, willow and birch.

While the City has used other methods to control the population of the insect, spray has been determined to be the most effective weapon.

The insecticide used is called Foray 48B, containing the active ingredient Bacillus thuringiensis subspecies kurstaki (Btk).

The spray produces fine droplets that are small enough to stick to the leaves of trees. Btk is a naturally occurring bacterium found in soil and has been approved by the Pest Management Regulatory Agency, an agency of Health Canada, for aerial use over urban areas.

According to Health Canada, Btk treatment is considered low-risk to human health and the environment. Btk is only toxic in the caterpillar stage of the LDD life cycle and does not affect adult moths or butterflies.

The spray will largely be contained to south Mississauga, particularly Clarkson, Lorne Park and Port Credit but will take place on a lesser scale in wooden areas in other parts of the city. In total, 2,100 hectares will be covered. A helicopter will be used to apply the spray.

 

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