Tree-bound bugs marked for death as Winnipeg begins spraying

City crews will start spraying trees for forest tent caterpillars starting this weekend and elm bark beetles later this month.

Forest tent caterpillar, elm bark beetle control programs get underway Sunday, weather permitting

The City of Winnipeg will begin its forest tent caterpillar control program on Sunday, weather permitting. (Marianne Klowak/CBC)

City crews will begin spraying trees for forest tent caterpillars starting this weekend and elm bark beetles later this month.

Weather permitting, workers with the city plan to fan out across insect management areas 43 and 51 Sunday at 9:30 p.m. and spray areas known to attract the pests, with a focus on municipal parks and boulevards.

Homeowners, on the other hand, are on their own when it comes to getting rid of the caterpillars.

"Current surveillance information indicates that the forest tent caterpillar larvae are feeding on the leaves causing many small holes known as 'shot hole' damage," Ken Nawolsky, superintendent of Winnipeg's Insect Control Branch, said Thursday in a statement.

"Winnipeggers can expect to see a significant amount of forest tent caterpillars throughout the city this May and June based on surveillance information."

As larvae, forest tent caterpillars chew their way through an assortment of leafy trees found throughout Winnipeg, including green ash, Manitoba maple, American elm and ornamental species.

City crews will use an organic product called Bacillus thuringiensis var. kurstaki (Btk) to stem the spread of the pests. It's available to the public at several Winnipeg garden and home stores.

The pests ingest leaves covered in the spray and die off in two or three days, according to the city.

Meanwhile, elm bark beetles will get sprayed with a Health Canada-certified chemical product — known as Pyrate 480 EC (Chlorpyrifos) — starting on May 23. Insect management areas 31 and 32 will be treated between 5:30 a.m. and 4:30 p.m. Monday through Thursday.

The mosquito control program got underway May 1. City crews are actively treating ponds and pockets of standing water around the city with a larvicide to kill young mosquito populations before they take wing.

City crews started administering larvicide to ponds and standing water in Winnipeg last week to kill off larval-stage mosquitoes. (James Gathany/CDC/Associated Press)

"The Insect Control Branch had a successful spring larviciding program," Nawolsky said in a statement. "Spring adult nuisance mosquitoes have emerged in very small numbers."

Fogging and other adult mosquito control measures won't begin just yet, as the most recent numbers showed mosquito trap counts across the city were at zero.

Winnipeggers who wish to be exempt from insect control treatment can apply for a 30-metre buffer zone order by calling or emailing the city (, or by visiting in person at 1539 Waverley St.

More information is available on the City of Winnipeg website.