Trap counts trigger mosquito fogging at city parks, golf courses, cemeteries

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This article was published 02/07/2020 (2087 days ago), so information in it may no longer be current.

Targeted fogging for mosquitoes will begin Friday with insect control officials focusing their efforts on stamping out the bloodsuckers in city parks with a new insecticide.

City insect control branch superintendent Ken Nawolsky said trap numbers have been trending higher than expected in recent weeks and the criteria for fogging was met Thursday with a city-wide average of 44 mosquitoes, with numbers highest around parks.

“What we actually saw is that these mosquitoes weren’t developed in Winnipeg,” Nawolsky said Thursday. “We have noticed that our trap count went down from 101 (Wednesday), down to 44 today.”

Officials believe winds have been blowing mosquitoes into the city from other areas in the southern part of the province. Sustained winds throughout June also distributed the bugs throughout the city, Nawolsky said, noting the city larviciding program appeared to be successful.

“What we’re noticing, is probably these mosquitoes are going to start to decrease in numbers and we hope that this fogging program we will start implementing will bring it down to a number that is much lower,” he said.

Before crews can fog, the city-wide “adulticiding factor analysis” has to be high, the city-wide average trap count must be a minimum of 25 female mosquitoes for two consecutive nights and one or more city quadrants must report at least 100 female adult mosquitoes.

Nawolsky said crews will be using a chemical called DeltaGard 20EW in place of malathion. Malathion was last used in 2016 and was determined to be “probably carcinogenic” by the World Health Organization in 2015.

Last year, the city got to experiment with DeltaGard — of which deltamethrin is an active ingredient — for the first time in select parks with plenty of mosquitoes. Nawolsky said the targeted application meant the bugs didn’t have a chance to spread to nearby neighbourhoods and the city was not required to fog in residential areas.

“We’re trying to do a systematic approach as opposed to going right into the neighbourhoods first,” Nawolsky said.

DeltaGard 20EW is classified as a reduced-risk pesticide and was approved by Health Canada in 2017 to control adult mosquitoes in residential and recreational areas. When deployed correctly, it’s less harmful to bees and other beneficial insects, as the small droplets kill mosquitoes through direct contact.

While DeltaGard is more costly — fogging the whole city would cost around $200,000 as compared to $90,000 with malathion — it has a lower rate of environmental persistence and requires one-eighth of the application, Nawolsky said.

Fogging will occur in Assiniboine Park, Brookside Cemetery, Charleswood Dog Park, Crescent Drive Park, Fraser Meadow Park, Harbourview Park, Harte Trail, Kildonan Park, Kildonan Park Golf Course, Kings Park, Maple Grove Park, Marj Edey Park, St. Vital Cemetery, St. Vital Park and Windsor Park Golf Course starting at 9:30 p.m., weather permitting.

Nawolsky said the job can be completed within 90 minutes, and officials will know within three days whether a second round of fogging is required.

danielle.dasilva@freepress.mb.ca

danielle.dasilva@freepress.mb.ca