In the spring of 1927, the City of Winnipeg launched its first anti-mosquito campaign to fight the pesky insect’s growing presence in the region. Nearly a century later, the City’s Mosquito Control Program continues to fight the good fight, and each year they work towards a single goal: reduce populations enough to achieve one mosquito bite per minute.
Winnipeg is especially prone to the insect, says superintendent of Insect Control David Wade. “We have very clay-based soils here and flat terrain, so when it rains we get a lot of standing water,” he says. These conditions create ample breeding grounds for mosquitos and are what first prompted the City to take action in the 1920s.
Early protocol involved dumping used motor oil from filling stations in mosquito-hatching areas, according to an archived Manitoba Pageant article from 1967. The practice, if rudimentary, was effective, and in the program’s second year, the budget grew and its boundaries expanded.
In 1949, the program switched from oiling to DDT spraying, and by 1965, the City employed an impressive fleet of insecticide-dispensing vehicles. This included ten trucks, eleven foggers, ten sprayers, one portable sprayer and duster, four air misters, and two boats.
Today, the program runs from mid-April until the end of September and spans the city boundary plus an eight-kilometre-radius buffer zone. Larviciding—the killing of mosquitos in their larval phase, prior to adulthood—is the program’s main effort these days, says Wade. This includes monitoring and treating over 28,000 hectares of water area using eco-friendly biorational larvicide dispensed with the help of backpack sprayers, trucks, ATVs, and four helicopters.
In addition to larviciding, the program monitors 28 adult mosquito traps across the city. “We use our network of traps to determine the average population of adult mosquitoes, specifically adult female mosquitoes because those are the ones that bite,” says Wade.
Success is determined by what the program calls “biting pressure.” When a citywide average of 25 mosquitoes collected per trap in one night is reported, biting pressure is measured at just one bite per minute. Last year, the City achieved zero days above one bite per minute, and as of August 18, the citywide daily average is five adult mosquitos per trap, according to the Insect Control website’s tracker. When adult mosquito populations do reach high nuisance levels, the City uses DeltaGard 20EW, an insecticide applied via fogging in concentrated areas.
Wade says programs like his are becoming increasingly important. “There’s the nuisance side of it, but there’s also mosquito-borne illnesses,” he says. “Right now the big concern is West Nile virus. Our mosquito control program helps keep the numbers of [West Nile-carrying] species lower in Winnipeg and surrounding areas.”
Approaching its 100th year, Winnipeg’s mosquito control program is the longest running and largest of its kind in the country. Wade shares that, aside from the odd complaint surrounding the use of insecticides, the program is positively received by Winnipeggers. “Residents are supportive of our program,” he says. “Our summers are short and so keeping mosquito numbers down is important to them.”
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