Larviciding takes a bite out of emerging mosquito population

Air and land attacks are underway to control Winnipeg’s annual bloodsuckers.

The city started its mosquito-larviciding campaign last week by using helicopters and trucks with sprayers to deliver the treatment.

That will kill mosquito larvae, preventing it from growing into biting adults.

“Our crews are out there larviciding on a daily basis now … both the aerial program, using the four helicopters you see around me, and a large … ground crew (is working),” said David Wade, superintendent of insect control, at the city’s Tyne Avenue heliport.

Wade said adult mosquito monitoring is also underway, with an average citywide trap count of one recorded Wednesday. The city deems that amount normal for this time of year.

To larvicide, the city uses a “biorational” program to monitor and treat more than 28,000 hectares of water, with exact treatments based on weather. The biorational method uses environmentally friendly, naturally occurring products.

While rain is expected in the next two weeks, the amount of surface water left behind will determine how much the mosquito population increases, said Wade.

Mosquito fogging will be ordered only when several key criteria are met, based on soil moisture, the weather forecast and the outlook for mosquitoes to emerge. The citywide trap count must also reach an average of at least 25 adult female mosquitoes for two consecutive nights, and at least one quadrant of the city must average at least 100 female mosquitoes on the same nights.

As the Free Press has reported, the city can’t order more of its fogging solution DeltaGard, since the product is no longer sold in Canada.

Wade said Winnipeg’s current supply should last about two years. In the meantime, insect control continues to search for a company to sell a comparable alternative product in Canada.

Last year, a staff report suggested city council could choose between several options to address the issue, including: increasing the maximum amount allowed in the insect control reserve to $5 million from $2 million to allow service to be ramped up when needed; creating a $200,000 master plan to reduce the number of sites that require mosquito treatment; and spending $600,000 to $850,000 per year to boost larviciding efforts.

City council did not act on the options, so no changes have been made to the mosquito control program, said Wade.

“We continue to follow our existing policies and use (DeltaGard) as required,” he said.

Winnipeggers will receive 24 hours’ notice before any fogging takes place.

joyanne.pursaga@freepress.mb.ca

X: @joyanne_pursaga