Mosquito Season Is Here

June 13, 2022

Mosquito season has arrived in the Fraser Valley, and some residents, particularly those living near the Fraser River, may begin to experience their annoyance. To reduce the number of these floodwater mosquitoes, the FVRD's annual nuisance mosquito control program is underway.

Crews with Morrow BioScience have been monitoring water levels since early May and have been applying the bacterial larvicide by ground since mid-May. Morrow BioScience provides mosquito control services for the Fraser Valley Regional District (FVRD) and has been conducting mosquito control for over 20 years within the Lower Mainland.

Residents may notice mosquito control contractors in their area wearing brightly coloured vests sampling the flood and seepage waters for mosquito larvae, the life stage targeted during mosquito control operations. This includes foreshore areas within the region as well as throughout the Fraser River Islands. Treatments and monitoring will continue through the summer for as long as water levels remain elevated.

Morrow BioScience advises residents that the larvicide they apply is not toxic to people, wildlife, or pets. “Morrow BioScience staff are out monitoring mosquito habitat and treating when necessary to reduce mosquito abundance in the FVRD. Our goal is to suppress mosquitoes to tolerable levels, allowing residents to enjoy outdoor activities,” said Dirk Lewis, Lead Biologist.

Lewis said residents can help reduce mosquito breeding sites around their properties by removing or refreshing standing water daily. These areas include bird baths, old tires, clogged gutters, animal troughs, and kiddy pools, to name a few. A toll-free hotline 1-888-733-2333 is available for residents to report an unusually high abundance of adult mosquitos or to ask questions about the mosquito control program.

Mosquito control activities

Mosquito eggs laid in previous years along the banks and seepage sites of the Fraser River are beginning to hatch. Floodwater mosquitoes are triggered to hatch in the presence of water, typically from the freshet, when the weather starts warming up and snow melt increases the Fraser River levels.

Once the mosquito eggs have hatched and the larvae have started to develop, mosquito control contractors apply a bacterial larvicide to the seepage water to kill the larvae. The larvicide is comprised of bacterial spores that affect mosquito larvae. When the mosquito eats the bacteria, it dies quickly. Mosquito development sites within the region will continue to be monitored until water levels recede. 

Morrow BioScience staff have been applying the bacterial larvicide by ground since mid-May. As the Fraser River rises, additional floodwater mosquito habitat is created. At peak river levels, helicopter treatments will occur along the Fraser River foreshore and Fraser River Islands. Higher-than-normal river levels are predicted for the season. As such, aerial treatments may be required from early June – July 2022. Ground treatments may continue through the summer, as dictated by environmental conditions.

The River Forecast Centre’s most recent Snow Survey and Water Supply Bulletin from June 1 notes that “Flood risk remains high due to the delayed melt of the mountain snowpack…”  Snowpack for the Fraser Basin is 164% of normal. If heavy local rain occurs in June as the Fraser River levels are high, higher-than-predicted River levels and additional seepage site development could occur. When this happens floodwater mosquito eggs that have been laid in previous seasons are triggered to hatch, compounding mosquito abundance. Flooding associated with the Fraser River within the FVRD may be similar to levels noted in 2011 and 2012.

What can residents do to protect themselves?

While Morrow BioScience staff will be doing everything possible to reduce mosquito levels, residents are encouraged to anticipate additional levels of mosquito annoyance. Stock up on bug spray, repair holes in household screens, and remember to refresh daily or dump out standing water around homes.

Residents are encouraged to reduce their exposure to mosquito bites through personal protective measures such as 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 an unusually high abundance of adult mosquitos or new seepage sites, or to ask questions about mosquitoes and the control program, please call the Fraser Valley Regional District’s Mosquito Hotline: 1-888-733-2333 or email:

Please visit Morrow BioScience’s website and social media sites to learn more about mosquitoes, treatments, and current activities:




Media contact:
Shaun Calver, Operations Manager
Morrow BioScience Ltd.