Mosquitoes enjoy ideal conditions in Calgary, but don't despair, says bug expert

An unusual amount of rain in a short period of time has provided a boost to the mosquito population in Calgary.

Heavy rain, standing water and heat create perfect breeding grounds

Entomologist John Swann says it only feels like an above-average season for mosquitos because Calgary hasn't had as many of them over the past few years. (Canadian Press)

An unusual amount of rain in a short period of time has provided a boost to the mosquito population in Calgary.

University of Calgary entomologist John Swann says the reason is simple.

"It was really easy up until late May, and then we had all those rains," he said. "Boom — 250 per cent of the normal precipitation for the month of May in the past week and a half. And that's what's got things started."

Right now, the large bodies of standing water are providing a perfect hatching ground for mosquitoes. 

"Those ponds are nice and big," Swann said. "So there's lots of breeding area."

Swann says it's time to start thinking about protecting ourselves from disease transmitted by the flying pests. 

"It's the later summer ones that tend to carry West Nile," he said. "Those are the ones that we have to be concerned about. So that's why I tell people, if you have to go out evenings or early mornings when mosquitoes are more active, wear long sleeves, long pants, lighter colours, use a repellent."

University of Calgary entomologist John Swann recommends a DEET-based repellent and keeping your grass trimmed. (CBC Calgary)

Swann says it only feels like an above-average season for mosquitos because we haven't had as many of them over the past few years. 

"Relatively speaking, the past three years, let's face it, we've had things pretty easy," he said, but noted conditions could still improve this summer. "I'm guessing from the looks of things we might get back to an average season here."

Alberta has about 45 types of mosquitoes, 20 of which can be found in Calgary at different times throughout the summer. 

Most of these are floodwater species, meaning they overwinter in the soil as eggs in areas that are prone to seasonal flooding. Then they hatch during spring and summer rains.

Swann recommends a DEET-based mosquito repellent of no more than 30 per cent DEET.

And your landscaping can help, too, beyond the obvious removal of any stagnant water in your yard.

Mow your lawn

"Keep your grass cut shorter," Swann said. "Because they're looking to get down in the heat of the day into the long grass. And the same with clearing out around your shrubs. Keep that relatively clear. It's less of a reservoir for them to sit in, in the heat of the day."

Mosquitoes can run through a life cycle in as little as seven days, and their ideal temperature is between 22 and 27 C during the day, and roughly 20 C at night.

Calgary's forecast for the next few days shows cooler temperatures, of between 14 and 17 C during the day, which could slow things down before warming up to 23 to 25 C for the weekend.

With files from Andrew Brown


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