Mosquito fogging rescheduled for last night

The City of Brandon was planning to fog for mosquitoes overnight Thursday after the work was cancelled Wednesday evening due to rain.

“For mosquito fogging to be effective, the product must adhere to dry surfaces where mosquitoes rest,” city spokesperson Merrilea Metcalf said in a press release late Wednesday.

“Wet conditions prevent the product from sticking properly and significantly reduce its effectiveness.”

The city will not fog if it is raining, the temperature dips below 13 C or the wind speed is more than 16 kilometres an hour.

Environment and Climate Change Canada’s forecast for Brandon on Thursday night didn’t project rain, but showed a low of 13 C and winds at 20 km/h, as of Thursday afternoon.

The parks department planned to start fogging Thursday at 9:30 p.m., with the citywide process taking about seven hours.

The city’s press release also highlighted that its DeltaGard pesticide stock is running low, and it doesn’t want to use the product if it’s ineffective.

“With a limited supply of product available, the city wants to ensure every application achieves the maximum possible impact,” the release said.

After this application of DeltaGard, the municipality will be left with enough product for only one round of fogging citywide.

The city is working with the province, the City of Winnipeg and Health Canada to find an alternative to DeltaGard, which stopped being sold in Canada in 2023.

On Monday, council voted to fog following a stream of complaints from residents over the annoying bugs. The decision came despite trap counts being lower than the threshold to start based on the city’s bylaw.

Meanwhile, the province announced Thursday that parts of Winnipeg and several rural communities will be sprayed for mosquitoes after the heat wave across southern Manitoba created a higher risk of exposure to West Nile virus.

The province has issued a fogging order under the Environment Act in response to a high number of Culex tarsalis mosquitoes — the primary transmitter of West Nile virus — in Manitoba.

Surveillance data from last week showed evidence of the West Nile virus.

“High temperatures across southern Manitoba have shortened the time required for West Nile virus to develop within infected Culex tarsalis mosquitoes and be transmitted to humans,” the province’s first bulletin on West Nile virus this summer, published Thursday afternoon, reads.

“The province is currently in the highest-risk period for human exposure, which historically occurs between July 15 and Aug. 15 each year.”

In trap counts from July 5 to 11, an average of 19.9 Culex tarsalis mosquitoes were found per trap, while from July 12 to 18, the most recent data available, an average of 154.9 Culex tarsalis mosquitoes were collected.

There have been no confirmed cases of West Nile virus in Manitoba so far this year. There were four confirmed cases of West Nile virus in Manitoba in 2025, and 10 in 2024.

A single bite from an infected mosquito can cause the virus to transmit to a human, and can result in serious illness, including brain swelling and death.

Spraying in the designated communities is set to begin today, weather permitting. DeltaGard 20EW will be sprayed within a three-kilometre radius of three intersections in Winnipeg, as well as in Carman, Winkler, Stonewall and the Rural Municipality of West St. Paul.

» The Brandon Sun, with files from the Winnipeg Free Press