This summer, prairie cities have experienced a surge in mosquito populations, leading to a shortage of bug spray in stores in Manitoba, Saskatchewan, and Alberta. Data from the City of Edmonton revealed a significant increase in mosquitoes, 15 times higher in July compared to the previous year. According to Peter Daly from the City of Edmonton, although this spike isn’t a record high for the region, it contrasts sharply with the past two summers, impacting public perception.
Cities like Saskatoon and Winnipeg also reported higher mosquito numbers this July compared to the previous year. In southern Ontario, experts attribute the prolonged mosquito season to record rainfall, creating favorable breeding conditions for species like Ochlerotatus trivittatus. Fiona Hunter from Brock University explained that these floodwater mosquitoes lay eggs in water-filled areas, which have been abundant due to the excessive rain in southern Ontario this year.
The persistence of Ochlerotatus trivittatus as aggressive biters has led to more human-mosquito interactions this year, contributing to the perception of a severe mosquito season. Additionally, the heavy rainfall in the Greater Toronto Area and other southern Ontario regions likely triggered the hatching of dormant mosquito eggs, further exacerbating the issue.
As temperatures drop, mosquito populations are expected to decline. Experts anticipate that once overnight temperatures fall below 10°C and frost sets in, mosquitoes will disappear. Recent cold snaps in Alberta have already led to a decrease in mosquito numbers, with Edmonton and Calgary experiencing a notably challenging mosquito season earlier. While Edmonton has seen a reduction in the dominant local mosquito species, Aedes vexans, warm fall weather has delayed a significant decrease in their numbers compared to previous years.
With temperatures forecasted to rise again in the region, mosquito populations may resurge, but are unlikely to reach the levels experienced in central Canada.