This 2003 photo from the Centers for Disease Control and Prevention shows a female Aedes albopictus mosquito acquiring a blood meal from a human host. (James Gathany/Centers for Disease Control and Prevention.)

Fraser River’s fluctuating water levels a ‘curveball’ for mosquito treatment

Mosquito larvae laying dormant in soil hatch when water levels rise

  • Jul. 14, 2020 12:00 a.m.

The Fraser River’s rising and falling water levels are making it more difficult to control mosquito populations, according to the treatment company under contract with the Fraser Valley Regional District.

Shaun Calver, the operations manager for Morrow Bioscience Ltd., said the although treatment has reduced the pests by 80 to 90 per cent this year, when the water rises to a new height and recedes, mosquito larvae laying dormant in the soil hatch.

“The river keeps throwing us a curveball,” Calver said. “Of course this happens in 2020.”

While all cities along the river are suffering the nuisance of the mosquito’s’ successful breeding year, Calver said Mission residents may be more affected because the city centre is so close to the river.

The treatment used by Morrow Bioscience is environmentally friendly and focuses on killing the blood-suckers before they grow wings. The company doesn’t use pesticides or fogging – in fact, no municipality in the Lower Mainland does.

Instead a granulated larvicide is used – starting in May – on hundreds of hectares on flood waters, dropped by either hand, canoe or helicopter.

The Fraser Valley Regional District has been putting out reminders to Valley residents to do their part to control potential breeding areas.

Residents can also help by removing breeding sites:

• Eliminate standing water;

• Chlorinate swimming pools;

• Empty wading pools; and

• Cover rain barrels with fine mesh.

FVRD has a hotline to answer questions or to report an abundance of mosquitoes 1-888-733-2333 or email

– With files from Jennifer Feinberg

RELATED: Mosquito sites being monitored and mapped across the Fraser Valley

Mission City Record

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