COVID-19 may have indirectly boosted mosquito numbers in one Fraser Valley neighbourhood. (Pixabay photo/File photo)

COVID-19 may have contributed to bad Fraser Valley mosquito season

Restrictions on helicopter occupancy may have resulted in less effective pesticide treatments

The COVID-19 pandemic may have played a role in making 2020 a particularly bad year for mosquitoes.

Weather and river conditions were the chief drivers of one of the worst mosquito seasons in recent memory. But occupancy limits in the helicopters that apply apply pesticides to mosquito breeding grounds may also have left some of the blood-sucking pests’ prime habitats under-treated.

A report to the Fraser Valley Regional District, notes that the season was shaping up fairly normally through June 5, when the river initially peaked. But instead of slowly receding over the summer, river levels dipped, then started to rise again, peaking once again on June 30 – above the level of the first peak.

Every year, the FVRD hires a private company to apply larvae treatments to mosquito breeding grounds along the river. In 2019, those wrapped up on June 21. But in 2020, the persistently high water required mosquitoes kept hatching through August. The last treatments were applied on August 17.

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

In all, just shy of 20 tonnes of one pesticide agent were used by Morrow BioScience, the company tasked with treating and eliminating mosquitoes. (The pesticides aren’t sprayed; rather a larvicide that the FVRD says is environmentally friendly is applied in granular or liquid form. The mosquito larvae ingest a toxic protein that kills them.) Even in 2012, another bad mosquito year, 14,489 kg were applied – 30 per cent less than this year’s total.

Each application of the pesticide kills about 90 per cent of larvae. But there were just too many mosquitoes in 2020.

“Based on the extremely high larvae abundance in 2020,” the FVRD report says, “despite the intensive treatment effort, the remaining 5-15% of surviving larvae that hatched into adults were enough to cause unfortunate annoyance in many lowland areas near the Fraser River.”

Last year, only four people called a mosquito hotline on which people can report the pests. This year, 130 calls were received. Of those, the vast majority – 99 – were from Chilliwack residents. And most of those were from Fairfield Island, the residential area of Chilliwack closest to the Fraser River and surrounded by sloughs.

The mosquitoes on Fairfield Island could be an indirect result of the COVID-19 pandemic.

Helicopter and boat crews were limited due to COVID-19 safety protocols. And while the report by FVRD staff said “these limitations are not believed to have significantly impacted the treatment efficacy,” a separate Morrow BioScience report suggested some potential effect.

“It is possible that sites were not treated as thoroughly as usual,” Morrow BioScience report said. “The high number of concern calls associated with Fairfield Island [in Chilliwack] indicate the possibility that sites on that island may have been over-looked.”

Do you have something to add to this story, or something else we should report on? Email:
tolsen@abbynews.com


Contact the reporter on Twitter at
@ty_olsen

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Construction has begun on the new Eagle Mountain elementary school in Abbotsford. (Screengrab from video by CHP Architects)
Construction begins on new Eagle Mountain elementary school in Abbotsford

School, including childcare spaces, is set to open in September 2022

Bill Hireen joined Remembrance Day celebrations in Abbotsford in 2019. The veteran and long-time civic supporter passed away on Dec. 31, 2020. (Abbotsford News file photo)
Long-time Abbotsford city council supporter dies of COVID-19

Bill Hireen was a frequent visitor to council and police board meetings

Uber Eats has announced that it is now delivering food orders in Abbotsford and Chilliwack. (Submitted photo by Justin Walker)
Uber Eats announces expansion into Abbotsford

Food-delivery company is staring with 60 local restaurants

Nakota Hinksman had been reported missing in Abbotsford, but has since been located.
UPDATE: Missing teen with autism has been located in Abbotsford

Nakota Hinksman, 18, had been missing since 3:20 a.m. on Tuesday

NHL Central Scouting has ranked three Abbotsford hockey talents as likely to be drafted in 2021. (Twitter photo)
Trio of Abbotsford hockey talents placed on NHL watch list

Abbotsford’s Chiasson, Milne and Sward all ranked as C grade prospects for 2021 NHL draft

Dr. Penny Ballem, a former deputy health minister, discusses her role in leading B.C.’s COVID-19 vaccination program, at the B.C. legislature, Jan. 22, 2021. (B.C. government)
B.C. holds steady with 407 new COVID-19 cases Tuesday

14 deaths, no new outbreaks in the health care system

Jonathon Muzychka and Dean Reber are wanted on Canada-wide warrants. (Courtesy of Victoria Police Department)
Convicted killer, robber at large after failing to return to facility: Victoria police

Dean Reber, 60, and Jonathon Muzychka, 43, may be together

B.C. Premier John Horgan listens during a postelection news conference in Vancouver on Sunday, Oct. 25, 2020. THE CANADIAN PRESS/Darryl Dyck
30% of B.C. recovery benefit applications held up in manual review

The province says 150 staff have been reassigned to help with manually reviewing applications

Adam Dergazarian, bottom center, pays his respect for Kobe Bryant and his daughter, Gianna, in front of a mural painted by artist Louie Sloe Palsino, Tuesday, Jan. 26, 2021, in Los Angeles. (AP Photo/Jae C. Hong)
Kobe Bryant’s presence remains strong a year after his death

Tuesday marks the grim anniversary of the crash that took their lives

Surrey RCMP are investigating after a pedestrian was struck and killed at 183 Street and Highway 10 Friday night. (File photo)
RCMP officers wearing face masks to curb the spread of COVID-19 stand by. (THE CANADIAN PRESS/Darryl Dyck)
RCMP appeal for witnesses after hit-and-run leaves girl, 17, in critical condition

The Metro Vancouver teenager was found unconscious and critically injured after being hit: police

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

The Brucejack mine is 65 km north of Stewart in northwestern B.C. (Pretivm Photo)
B.C. mine executives see bright gleam in post-COVID future

Low carbon drives demand for copper, steelmaking coal

In this Dec. 18, 2020 photo, pipes to be used for the Keystone XL pipeline are stored in a field near Dorchester, Neb.  THE CANADIAN PRESS/AP-Chris Machian /Omaha World-Herald via AP
Canadians divided over Keystone pipeline, despite U.S. president’s permit pullback

Two-thirds of Canadians think Biden’s decision was a “bad thing” for Alberta

Most Read