British Columbia

Number of mosquitoes 'higher than normal' in Lower Mainland this year

The increase in mosquitoes is concentrated in the Fraser Valley, especially Fort Langley, Walnut Grove, and Maple Ridge.

High water levels create ideal conditions for mosquitoes to hatch, experts say

It's a banner year for mosquitoes, thanks to a wetter than usual spring and high river levels. (mycteria/Shutterstock)

Have you gotten more mosquito bites than usual recently? 

Experts say you're not imagining it. 

"Mosquitoes are definitely higher than normal for this time of year," said Shaun Calver, the operations manager at Morrow BioScience, a company specializing in mosquito control. 

Calver said their mosquito hotline for Lower Mainland residents who live along the Fraser River has received more calls than usual this summer. 

He said mosquito populations flourish during years of heavy rain and high water levels in the Fraser River. 

A Morrow BioScience field worker is pictured applying a non-toxic granule that targets mosquito larvae to the floodwaters created by the Fraser River in June 2022. (Shaun Calver)

Morrow BioScience is contracted by local governments to control mosquito populations. Calver said they do this by applying a non-toxic granule to mosquito larvae on the banks of the Fraser River. 

The treatment destroys about 85-90 per cent of mosquitoes before they emerge into biting adults. 

"That 10-15 per cent on a high-water year, such as this year, is causing an increase in annoyance numbers," said Calver. 

Fort Langley, Walnut Grove, and Maple Ridge are mosquito hotspots, according to Calver. 

Carl Lowenberger, a professor of entomology at Simon Fraser University, said the pests that are prevailing at the moment are a type of mosquito called floodwater mosquitoes. 

"They're certainly causing a lot of irritation to many people," said Lowenberger. 

They lay their eggs on the banks of rivers, where they can accumulate for years until a high precipitation year causes the rivers to flood and the eggs to hatch.

Furthermore, Lowenberger said the hatched mosquitos' development has been delayed due to cold weather this year. 

Now that temperatures are finally rising, mosquitoes are developing quickly in a short amount of time, rather than throughout the summer. 

"Anyone who's been active in the cooler temperatures has probably noticed there have been fewer mosquitos. We're all paying the price right now," said Lowenberger. 

Keeping pests away

Lowenberger said mosquitoes are not very good flyers but will slowly fly toward humans. They can catch up when a person stands still in one spot. 

"If you're hiking in a mosquito area, just keep on going. Don't slow down, don't let them catch up to you."

Calver said dawn and dusk are the worst times to be outside for mosquitoes. 

For those who will be outside during those times, he recommends wearing light-coloured clothing and repellant with DEET, a chemical that repels mosquitos. 

Calver says the situation will start to improve in a couple of weeks. 


Michelle Gomez is a CBC writer in Vancouver. You can contact her at

With files from Philip Owira