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Gypsy moth spraying expected to begin this week

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Troy Shantz

The on-again, off-again gypsy moth spray program is expected to begin this week, depending on the weather and development of moth larvae, City Hall says.

Spraying with a biological insecticide was to begin May 15, then May 20. City council met Friday via teleconference specifically to overturn its April decision to spray, then approved it anyway.

“The important component to the whole program is you’re going to spray when the greatest number of caterpillars have emerged, so it can be most effective,” said parks and recreation director Rob Harwood.

Gypsy moths, an invasive species whose caterpillars can quickly defoliate trees, attacked pockets of the urban forest last summer.

The target area is 64 hectares (157 acres), which includes Canatara Park and Lake Chipican Drive, Oak Acres Park, Lakeshore Road east of Modeland, and Colborne Road north of Michigan, south of Cathcart, and east to Errol Road and Ridgewood Drive.

Sarnia has hired a company with a twin-engine helicopter to spray those areas with Bacillus thuringiensis v. kurstaki (Btk), a bacterium found naturally in soil and successfully used for 30 years as a pest control agent on woods and agricultural crops, the city says.

Weather conditions must be right for a low-flying helicopter and to prevent drift of the spray.

Staff says the moths could cause permanent tree damage if left unchecked. Recent inspections found less than 35% of the larvae had emerged in the target areas, Harwood said.

Residents may have recently noticed trees in Canatara Park tied with pink ribbon, which are monitor trees.

Spraying each area will takes about 15 minutes and occur between 5 a.m. and 8 a.m. Harwood said.

The schedule will be posted at, Facebook and Twitter prior to spraying, which is highly dependent on weather conditions and subject to change.

Homeowners within the four spray zones were sent a letter, Harwood said. Additional information can be found at

The program, expected to cost $82,000, was almost scrapped in April when council cut costs to deal with the COVID-19 pandemic.
For more on Btk visit the Government of Canada’s website:



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