Summer of mosquitoes in store for Ottawa, experts say

Experts say wet weather has left pools of standing water where mosquitoes can breed safe from predators. (CBC - image credit)
Experts say wet weather has left pools of standing water where mosquitoes can breed safe from predators. (CBC - image credit)

Bug experts are predicting a good summer for mosquitoes and a bad one for Ottawa-area residents, as weather conditions create ideal breeding grounds for the unpopular insects.

"The combination of this year being wet, on top of last year's drought, makes it look to me that this year is a good year for mosquitoes," said Davis Beresford, an associate professor of biology at Trent University who specializes in biting insects.

Beresford, who lives east of Peterborough, said he's already experiencing the abundance of mosquitoes whenever he steps out of his country home.

"I haven't seen anything like this in 15 years," said Beresford, who noted that conditions are similar in the Ottawa area.

He explained higher water levels in rivers, streams and ponds leave little puddles as they subside. Once those puddles become isolated from larger bodies of water, the mosquitoes can lay their eggs and thrive free from predators.

Beresford also noted dry weather from last year could mean fewer predators overall to eat the mosquitoes, notably dragonflies.

"There's a lot more mosquitoes, adult mosquitoes, in response to that," he said.

He predicted the worst time — that is, the best time for the mosquitoes — will begin now and taper off in July and August, before picking up again in the fall.

Mark Ardis, scientific advisor at GDG Environment, agreed this summer "absolutely" could be a bad one for those trying to fend off the pesky little insects.

"We had a winter with a lot more snow, which translates into more of these vernal pools," he explained. "And because the water table is high that means that any rainfall event will cause pooling which is a potential breeding development site for mosquitoes."

He added that different species of mosquitoes hatch and grow into adults at different times. There are more than 40 species in the Ottawa area, Ardis said. Cooler temperatures could lead to springtime species living longer and joining their summertime relatives.

"We're probably going to be seeing these mosquitoes stick around a little longer," he said. "So you're going to get an overlap on different species."

Beresford agreed that's a possibility.

According to Ardis, climate change has also increased the range of some species, with three southern types now emerging in the Ottawa area. None are dangerous as transmitters of disease, however.

Reducing mosquito populations

Ardis works as project manager on a mosquito control project for the Kanata North ward. The program uses a bacteria-based larvacide that attacks mosquitoes at the source, that is, in the standing water where their larvae develop. The program aims to reduce mosquito populations by 80 to 90 per cent.

Beresford advised residents to be aware of unknown or tucked away puddles of water that could accumulate around their homes, including in storm drains.

He said DEET-based insect repellent remains the "gold standard" for warding off mosquitoes, though it's only necessary to put a small amount on the cuffs of clothing.

"A couple drops spread on the way you can put perfume on is ideal," he said. "It's not sunscreen."

Beresford also urged residents to avoid letting mosquitoes ruin their summer.

"The psychological health of being outside just far outweighs the irritation, in my opinion."