Winnipeg ramps up mosquito fight after weekend downpour

Winnipeggers should expect more mosquitoes in the next week, thanks to the significant amount of rain that fell over the weekend, city officials are warning.
Winnipeggers should expect more mosquitoes in the next week, thanks to the significant amount of rain that fell over the weekend, city officials are warning. 2:01

Winnipeggers should expect more mosquitoes in the next week, thanks to the significant amount of rain that fell over the weekend, city officials are warning.

Winnipeg received as much rain over the weekend as what it would normally get in the entire month of June, and the second generation of summer nuisance mosquitoes have started to hatch in bodies of water.

"The eggs that have laid dormant for the last three to five years have hatched in the water because of the significant amount of rainfall," Ken Nawolsky, superintendent of the city's Insect Control Branch, told reporters on Tuesday.

"Mosquito eggs can last up to seven years in the soil, remaining dormant," he added.

Ken Nawolsky, superintendent of the City of Winnipeg's insect control branch, shows reporters a container of standing water from a home in Charleswood. The water sample alone contained 200 mosquito larvae, he said. (Nelly Gonzalez/CBC)
Crews are applying larvicide in pools of standing water across the city, but officials are urging homeowners to help reduce the number of mosquitoes by removing any standing water from their properties right away.

Nawolsky showed reporters a container of standing water, containing about 200 mosquito larvae, from a home in the Charleswood neighbourhood.

"We need people's co-operation in helping to look for standing water sites like this," he said as he held up the container.

"If you get sites like this that are not being treated, then that will really have a significant impact on the emergence."

Fogging not necessary right now

As of Tuesday, the city's average mosquito trap count is currently set at nine, but Nawolsky said the highest trap number at this time is 99 at Brookside Cemetery.

The adulticiding factor analysis (AFA) rating is set to medium, meaning crews will use larvicide and "residual treatments" on city properties where necessary, but fogging is not necessary.

Nawolsky warned that any more rainfall this week could hurt larviciding efforts.

The bad news: more rain is in the forecast starting on Wednesday, said CBC meteorologist John Sauder.

Sauder said rain and possibly some storms will move into western Manitoba on Wednesday afternoon, then reach the Red River Valley that evening.

"More rain is on the way for Thursday and Friday. Showers are still in the mix for the first half of the weekend," he wrote in his daily weather journal. "Mosquitoes love this stuff!"

While trap counts are not high enough for fogging at this time, the city says homeowners can register now to be in a buffer zone if they don't want their properties to be fogged.

Among those who plan to register for a buffer zone is James Penner, who lives in Wolseley.

"I don't let my son run around without bug repellent on, but I use an organic essential oil repellent so he's not getting chemicals in his system," Penner said.

River Heights homeowner Sharon Weinstein said she would support any fogging the city carries out this summer.

"I just put a plant out there a few minutes ago and within seconds the mosquitoes were swarming," she said. "Being a very shaded yard, you know, we always have a lot of mosquitoes."

Could take 7 to 10 days

Both Nawolsky and former city entomologist Taz Stuart, who is now director of technical operations at Poulin's Pest Control, said it could take seven to 10 days for mosquito larvae to turn into adults.

"All the boys and girls in the Insect Control Branch will be working hard, probably doing a 7/24 run," Stuart told CBC News on Monday.

"That's what has to happen, trying to reduce the potential emergence that may be occurring in the next seven to 14 days."

Nawolsky said the insect control branch's 160 staff and four helicopters are putting in 16-hour days to monitor and treat 30,000 hectares of "potential larval development sites" in the city and in a 10-kilometre area around it.

Officials said 50 per cent of standing water sites in Winnipeg are located on private properties, which is why it's important for homeowners to do their part by draining water on their yards and cleaning out their eavestroughs.

"There's no standing water on my yard. You can come look if you like, guaranteed. Even eavestroughs are clean," Stuart said.

Homeowners can also treat the standing water on their properties with a product called Bacillus thuringiensis israelensis (BTI), a biological insect control agent, he added.

"It's a bacteria that when they ingest it — because they're filter feeders — goes to their gut lining, causes literally an imbalance, gives them a bad stomach ache and they die because of it," he explained.

And if Winnipeggers do come across adult mosquitoes, Stuart suggested using insect repellents containing permethrin.

With files from the CBC's Nelly Gonzalez


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