Mosquito swarms irk visitors to Fort Langley, Fraser River’s shores

Ed Davis said he didn’t quite put enough Off insect repellent on Friday before a visit to Fort Langley.

“I forgot the ankles,” he joked.

“Next time, I’ll be more prepared,” said Davis. “I’ll put more Off on.”

People all over Fort Langley and other areas of North Langley are slapping mosquitoes this year, one of the worst in recent memory for the blood sucking insects.

Karen and Tom Corwin, riding their bikes in North Langley from Maple Ridge, said it started about two weeks ago.

As of Friday, July 15, things were slightly better.

“Beginning of the week, we couldn’t even sit here,” Karen said.

Neither could remember a year with quite so many mosquitoes.

“Maple Ridge is bad as well,” said Tom.

The reason for the bumper crop of mosquitoes is the high water on the Fraser River. Mosquitoes lay eggs on the river banks, and they lay dormant until the next year’s snow melt and high water. The water hits the eggs, and they hatch. This year’s freshet was so high, and so late, that it hatched a lot of eggs all at once.

Shaun Calver is the operations manager for Morrow Bioscience, who do nuisance mosquito control for Metro Vancouver. He said the region is seeing about three years worth of mosquito hatches this summer.

Mosquito eggs can lay dormant for a decade, said Calver, waiting for water.

“High water on the Fraser and high mosquitoes go hand-in-hand,” he said, noting the river is at its highest flows in four years.

Morrow Bioscience deals with the biting bugs by killing them in the larval stage. They spray a non-toxic, naturally occurring bacteria that kills 85-90 per cent of the larvae, he said. Shorelines are “treated” both by helicopter and by hand sprayers. Morrow workers even paddle into inaccessible areas to spray, and kill as many bugs as they can. 

But there are lots of survivors, and with three years of hatches “stacked” into one, there’s still whole squadrons of the pests left to land on our legs.

“That remaining 10-15 per cent left is significant,” said Calver, and the many complaint calls to Metro indicate that the public wants to know what’s up.

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Calver said these are not vector mosquitoes, and there is no concern about them causing illness.

“These are strictly nuisance mosquitoes.”

He said people who are bothered by them should avoid being outside at dawn and dusk – the worst times for the bugs. Wearing light clothing attracts them less than darker shades. And there are of course commercial repellents of varying effectiveness. But they find their prey when they exhale, because they are attracted to carbon dioxide, so there is no hiding.

Mosquitoes lengthen their life cycle by staying in the shade of trees and tall grass during the day, taking flight when it is cooler.

“The hotter the weather, the faster they die,” said Calver, adding that people should notice an improvement by early August.