Saskatchewan

Record-breaking Regina mosquito boom came before city had pesticides fully in place

Regina reached a historic number of mosquitoes for June last week. Experts believe recent weather is to blame.

Population will even out as year goes on, predicts U of S professor

There were more than 3,500 mosquitoes counted in control zones in Regina during the last week of June, far more than the 77 caught over the same period last year. (Felipe Dana/The Associated Press)

Regina reached a historic high for the June number of mosquitoes last week. Experts believe recent weather is to blame.

Regina has been tracking mosquito population numbers since 1988. The last week of June this year was the highest population count the city has ever seen in the month, said Ryan Johnston, the supervisor of pest control for the city. 

There were an average of 293 mosquitoes per trap found in the 12 traps across the city. Last year, around the same time period, there were only six mosquitoes per trap on average. 

Populations tend to spike in July, Johnston said, but the recent warm weather, followed by rainfall, allowed the mosquitoes to flourish. 

"That's the worst June posting we've ever seen," he said. 

Sean Prager, assistant professor of plant sciences and an associate member of the biology department at the University of Saskatchewan, agreed that the recent weather is most likely the reason for the increased mosquitoes. 

"A combination of hot and wet is usually the thing that will do it," he said. "If you have an extended period of time, say, where there's no rain then it rains all of a sudden, all those mosquitoes waiting to lay eggs, or the eggs that are hatching, come out."

Prager predicted that while Regina is seeing record numbers for June, it likely won't see a record for the entire year. He said numbers will even out as the year goes on. 

Typically the city controls the mosquito population by using VectoBac, a pesticide that kills the mosquito larvae at sites where mosquitoes lay eggs while being harmless to other animals and humans, rather than fog-based pesticides. 

Johnston said the city wasn't able to deploy Vectobac quickly enough this time. He estimates there are about 2,000 sites it needs to manage. 

It is a chemical that is put into the air. It is a non-target chemical so it will kill anything.- Ryan Johnston, Regina supervisor of pest control, on why city doesn't use fog pesticides

Johnston said there is a "zero per cent" threat of the West Nile virus in the city. Only a few of the mosquitoes that can carry the virus were found in the traps, he said.

Mosquitoes carrying the West Nile virus become more of a threat in the later summer months as weather remains hot and dry, Johnston said. (Arnulfo Franco/The Associated Press)

Some communities, like Shaunavon, Saskatchewan, use a fogging method that sprays mosquito-killing chemicals into the air. 

Johnston said Regina has never fogged and chooses not to. 

"It is a chemical that is put into the air. It is a non-target chemical so it will kill anything … beneficial insects," he said. "We're all breathing it in, we have pets, we have children."

Johnston recommends wearing repellent to keep the mosquitoes away and ensuring your backyard doesn't have still, stagnant water, which can be a good breeding ground for the insects. 

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