Bad buzz: warm weather good for mosquito growth

With heat warnings in place across the province, Saskatchewan’s insect population could see an increase.

In particular, those outdoors might notice some more mosquitoes buzzing around.

Sean Prager, associate professor in the Department of Plant Sciences at the University of Saskatchewan, says temperature increases cause quicker insect development.

Prager said extreme heat has the ability to kill insects, but it would require temperatures much higher than what can typically be found in Saskatchewan.

There are several dozens of types of mosquitoes in the province but often aren’t thought of because the majority of them don’t bite people.

“They feed on other things, and so we tend to not really be very cognizant of them as lay people,” Prager said.

“Most of them will increase their populations with increased temperature.”

Rainfall is another major factor in the growth of the mosquito population since mosquitoes are aquatic when they are larvae.

“Baby mosquitoes live in puddles of water and the eggs are usually laid out in the water or right next to it. Because of that, we generally expect populations to increase – we expect there to be more mosquitoes when you’ve had more rainfall events,” he said.

Although that’s what generally happens, Prager said it can depend on the species and some like to lay their eggs in ponds, containers and tree holes.

Fortunately, Prager says mosquitoes and Saskatchewan are unlikely to carry West Nile Virus.

The Ministry of Health conducts surveillance for West Nile every summer by monitoring Culex tarsalis – which is a type of mosquito that carries the virus.

“Consistently warmer temperatures will decrease the amount of time it takes for Culex tarsalis mosquitoes to develop. It also significantly shortens West Nile virus (WNV) development time in mosquitoes,” wrote the ministry in a statement to 980 CJME.

“Warmer temperatures increase the potential risk of WNV transmission if the virus is present and other conditions are favourable,” said the ministry.

The government provides weekly reports on its findings and as of this season, it has not recorded any cases of West Nile in Saskatchewan this year as of July 6. 2024.

The province says people can reduce their exposure to mosquitoes by reducing the amount of standing water around their homes and yards, ensuring door and window screens are tight and free of holes and avoiding being outdoors during peak mosquito hours (dusk and dawn).

Saskatoon

Sydney Worthy, entomologist with the City of Saskatoon, said the city has the ‘perfect storm conditions’ to see a major spike in its mosquito population.

On Wednesday’s CKOM Morning Show, Worthy said this is being reflected in the city’s weekly mosquito counts.

“We’ve had some more heat, so mosquitoes are starting to develop but we’re still having lots of precipitation so that’s allowing for those water bodies that they need to develop in,” she said.

Worthy said the city uses larvicide as its only form of mosquito control since it doesn’t target the mosquitoes once they reach adulthood.

In addition to clearing standing water, Worthy also said people can reduce the presence of mosquitoes by keeping the grass short on their yards.

While the time it takes for mosquitoes to grow depends on the temperature, Worthy said it can take seven to 10 days.

Regina

Russell Eirich, manager of open space services with the City of Regina, predicted a surge in Regina’s mosquito population in June due to the heavy spring/summer rainfall and subsequent warm weather.

Last week, the city counted 311 mosquitoes in its traps within Regina for Week 28 of its program.

In 2023, the city counted 146 in the same week.

In rural areas which are outside of Regina’s “control zone”, 76 total mosquitoes were caught in Week 28 this year compared to 74 last year.

“City crews monitor for mosquito larvae by taking samples from water bodies in the city and up to 10 km outside city limits,” reads the City of Regina’s mosquito report.

“If larvae are found, crews treat the water with a biological larvicide called VectoBac.”