Bad bug season ahead for many, forecaster says. Here's why

Friday, July 3, 2015, 3:00 AM - This summer will be worse than usual for mosquitoes and blackflies in many areas of the country, according to G.D.G. Environment, a company based in Trois-Rivieres, Que.

G.D.G. helps produce The Weather Network’s daily Bug Activity Forecast for thousands of these cottage-country forecast locations and campsite forecast locations.

“It’s a tool I myself use when I go to the cottage,” said Marc Ardis of G.D.G. “If you’re low on deet [insect repellent], this will tell you whether or not you need to buy some.”

It’s not just cottagers and campers who should be aware. Mosquitoes prefer man-made sites and the risk for contracting the mosquito-borne West Nile virus lies more in urban areas as opposed to cottage country, noted Ardis, who manages projects for West Nile programs for the province of Ontario.

The virus causes swelling of the brain which can result in severe headache, high fever, confusion, weakness, coma and even death. There’s no vaccine or cure, only treatment for the symptoms which can take as long as 90 days to pass. The very young and old, as well as others with weakened immune systems, are most susceptible.

Here’s what to expect in your region this season.

Ontario and Quebec

Given the late spring Ontario and Quebec had this year, snow melt was behind 15 days compared to other years, Ardis explained. Melting snow creates standing water, the perfect breeding ground for mosquitoes. This is why both Ontario and Quebec have seen a spike in mosquito populations.

The good news is spring mosquitoes are starting to die-off. The bad news is the summer generation has arrived. Summer mosquitoes are driven by rainfall, according to Ardis.

“Whenever we have a certain amount of rain, we will have a new generation of mosquitoes. We use 20 mm as a gauge and the more rain we get, the more mosquitoes we will have.”

While some spring mosquitoes can live up to three months, the average lifespan for summer species is approximately 14 days.

Blackflies were also a nuisance this spring in Ontario and Quebec. Originally, G.D.G predicted low activity for blackflies. But above normal precipitation in both regions created more streams.

“Blackflies prefer running water. We had more streams and this created perfect conditions for the populations we have experienced,” said Ardis. "The other thing is we've had good hot days but we've also had cool nights. What happens is these temperatures allow them to develop more quickly and cool downs mean adults aren't dying off."

Blackflies have a lifespan of 20 days to three months.

Horse and deerflies are also prominent in Ontario and Quebec. These insects can live up to two months and prefer slow-moving water and muddy conditions. They are starting to emerge in both regions, according to Ardis. These insects are able to fly in the wind due to their size. Horse and deerflies begin to die-off around the end of August.

Mosquito emerging from its nymph stage. Photo by Paul Turton, Wainfleet, Ont., July 15, 2014

Atlantic Canada

New Brunswick and Nova Scotia experienced similar mosquito and black fly populations to Ontario and Quebec, Ardis explained. However, in Newfoundland and Labrador, spring-like conditions typically last longer. Therefore, blackflies could last the entire summer due to cooler conditions.

“Basically what allows the population to die-off is a nice and long heatwave,” Ardis said. “What happens is they get generation after generation of blackflies and mosquitoes and there is no heat to kill them off.”

Western Canada

Mosquitoes are very prominent in the Prairies given the fact that the area is flat, as they prefer standing water.

Blackflies are prominent in Alberta and British Columbia due to these areas being so mountainous. There are a lot of streams for these insects to lay eggs.

Editor's note: An earlier version of this story incorrectly referred to culex tipiens as a species of mosquito. The correct species is culex pipiens. The current update of this story no longer contains the sentence with the error.