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Mosquito eggs starting to hatch along banks and seepage areas of Fraser River

It’s mosquito season! Contractors working to keep floodwater mosquitoes at bay
FVRD mosquito control contractor Morrow BioScience conducting larvicide treatment by helicopter near Chilliwack on May 27, 2014. (Morrow Bioscience)

Local mosquito control contractors for Fraser Valley Regional District (FVRD) have been working away at reducing mosquitoes since the season rolled in with the Fraser River freshet.

Mosquito eggs are starting to hatch now along the banks and seepage sites of the Fraser River.

“We are doing our very best to reduce floodwater mosquitoes so that they remain at tolerable levels and allow residents to be able to enjoy outdoor activities,” said Dirk Lewis, lead biologist for Morrow BioScience in a news release June 10.

The eggs are triggered to hatch as freshet waters start to reach them, and as snow melt raises river levels.

Morrow BioScience technicians have been applying bacterial larvicide on the ground since mid-May, followed by helicopter treatment of the Fraser River foreshore and islands the first week of June.

Whether or not the summer of 2021 becomes a bad season remains to be seen, depending on temperatures and water levels after the river peaks.

In a bad year people will call the FVRD hot-line to demand they “spray” for mosquito eradication. But that toxic method of mosquito control went the way of the dodo.

These days they employ a bacterial agent, Bti, to kill mosquito larvae, which is non-toxic to pets, fish and wildlife. It is ladled by hand, or dropped from a helicopter into the water. Bti which naturally occurs in soil stands for Bacillus thuringiensis subspecies israelensis.

When the mosquito larvae eat the bacterium spores, they quickly die.

“The aerial and ground treatments may continue through the summer, as dictated by environmental conditions necessary for floodwater mosquito development,” according to the news release from Morrow BioScience.

Technicians in high-vis vests may be spotted sampling water in watercourses along the banks of the Fraser River or local waterways, to see if they contain mosquito larvae and in what concentrations.

Residents can help reduce mosquito breeding sites around their properties by removing or refreshing standing water daily. Reduce bites by wearing long-sleeved shirts and pants, choosing light-coloured clothing, using insect repellent, deploying mosquito netting at home, and ensuring window screens are properly installed and maintained.

To report standing water or adult mosquito nuisance, call the FVRD’s Mosquito Hotline at 1-888-733-2333. Or email:

RELATED: Contractors map out breeding sites

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Jennifer Feinberg

About the Author: Jennifer Feinberg

I have been a Chilliwack Progress reporter for 20+ years, covering the arts, city hall, as well as Indigenous, and climate change stories.
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