Fewer mosquitoes seen around Calgary this spring
If you're wondering why you haven't had to reach for your bug spray while out on your backyard deck, officials say you shouldn't have to look much further than Calgary's recent forecast for an answer.
Many mosquito species lay their eggs in soil close to the water level of sloughs or ponds. Those eggs can live for years during a drought and will hatch when the water level raises and covers them.
Low precipitation at the end of winter and into spring in Calgary means those water bodies around the city are not as high as they normally are, according to Alexandra Pepperdine, an integrated pest management technician with the City of Calgary.
"We did have a little bit of rainfall over the long weekend but it didn't seem to be enough to fill up a lot of the habitat that's out there," said Pepperdine. "It looks like the ground sucked up a lot of it so things started out really dry."
Ray Blanchard is an 80-year-old wildlife photographer who likes to make movies of what he sees. He says he's been bitten by mosquitoes so many times that their bites don't bother him any more. But this year, Blanchard has noticed around his home near Chestermere that he hasn't seen any mosquitoes.
"I think there are things that could come out of this," said Blanchard. "If people could figure out why these mosquitoes are disappearing maybe they can find a better way of controlling them, I think research into this is vital."
There are about 20 species of mosquitoes that call Calgary home. They hatch at different times throughout the spring and summer months. One species is responsible for West Nile virus and the city monitors them using carbon dioxide traps that specifically attract female mosquitoes.
The Calgary Zoo says mosquitoes are a nuisance for most of its animals but Dr. Sandie Black, head of veterinary services and senior manager of animal health says extra care has to be taken for the zoo's avian collection. New world birds are susceptible to West Nile virus and upwards of 200 need an annual vaccine for it.
"It's a vaccine that's made for horses so the dose is quite high," said Black. "We use one millilitre which is a pretty big volume to put into those birds but we split it into two places for the injection, other than that instead of getting it in their arm they get it in their chest muscles because if you fly that's the biggest muscle you have."
The city uses other traps to capture mosquitoes and calculate overall numbers of the pests. Technicians also visit still water ponds looking for mosquito larvae. Pepperdine is seeing a lot of them.
"And with this heat they can go from an egg to adult in really just a matter of days depending on species," said Pepperdine. "So we might start seeing more in the next few days."
When the mosquito count reaches a certain threshold, the city uses a biological pesticide that is safe to everyone and everything accept mosquitoes larvae.
"In terms of the larvae monitoring it's important for us to try to see if we can control mosquitoes in problem areas," said Pepperdine. "Just to make basically our parks and outdoor spaces more enjoyable for people."