Mosquitoes given the cold shoulder
But potential for spring slapfest remains, bug experts warn
The cold, snowy spring has helped keep mosquitoes in check so far this year, but Edmonton residents will be slapping again if warm, rainy weather returns, city officials said Wednesday.
Crews started spraying standing water in ditches, fields and ravines April 15. They finished 80 per cent of the work before they were interrupted by the recent snow, said James Wilke, director of animal control and pest management.
While the sudden cold probably killed some of the mosquitoes that hatched and were flying, he said jokingly that it did create problems.
“We never thought we would have axes and ice augers as part of the mosquito control program.”
The main tool in the annual fight is spraying from as many as three helicopters, with 10 staff taking chemicals in backpacks to hard-to-reach areas and using trucks to treat ditches, biological sciences technician Mike Jenkins said.
They target concentrated populations of aquatic larvae that are easier to hit. Fogging for adults is less effective, can kill beneficial species such as dragonflies, and exposes people to chemicals.
“This has been one of the weirdest springs I think we have ever seen in terms of the weather conditions, and that has had a huge impact on the program,” he said.
“It hasn’t been one big rapid melt that would result in large habitats developing. It’s slower. That has given us a larger window of opportunity to go after that habitat and control it. We’re pretty confident we have a good handle on it.”
Their data shows that, on average, the bloodsucker swarms are two to five times smaller in areas where the city takes control measures, Jenkins said.
The large, unaggressive mosquitoes people are now seeing have actually survived the winter and don’t pose much of a nuisance, he said.
The new crop of biters typically starts showing up in early May, but this year their arrival should be delayed until the middle or end of the month, Jenkins said.
“We’re seeing fairly low numbers in the areas we have treated,” Jenkins said. “At this point, it looks good, but that could change.”
The main danger to this rosy situation is wet weather.
“If we get … a lot of rain and a hot spell, we will be out with another program,” Wilke said, adding the work costs about $1 million a year.
In 2011, heavy winter snow and spring rain meant Edmonton faced clouds of the flying pests unseen during the previous decade of drought, with up to 9,000 mosquitoes a week caught in each light trap.
That figure dropped to a more tolerable 145 mosquitoes in each trap last summer, despite several July downpours.