Every day during the late spring, summer and early fall, the City of Winnipeg’s insect control branch counts the number of adult female mosquitoes that show up in traps designed capture nuisance species such as Aedes vexans, which are annoying but do not transmit diseases to human beings.
There are 24 traps in city limits, six in each quadrant of the city. The city-wide trap count for any particular day is an average of all 24 traps.
A nuisance-mosquito fogging program may commence when two conditions are met. First, the city-wide average trap count must be 25 or more for at least two consecutive days. Secondly, one city quadrant must have a trap count of 100 or more during the same time frame.
The insect control branch also has nine traps set just outside city limits, where the city may also fog. But these traps do not count toward the city-wide average.
A different type of trap and trap-count methodology is used to monitor Culex tarsalis, a mosquito species known to transmit diseases such as West Nile virus to people. The province makes decisions about West Nile-control fogging programs.
The graph above is updated daily based on the average citywide trap count information provided by the City of Winnipeg. To find out more detailed information, such as trap counts for specific quadrants or traps, visit the city's trap count site.
Sure, there's been an uptick in mosquitoes this year — compared to the previous two dry, buzz-free summers — but really it's not so bad when you look at the peak weekly average trap counts for the last three decades. The graph below shows the best and worst skeeter summers since 1982, according to data provided by the City of Winnipeg.
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