City to spray pesticides to stave off 2022 moth infestation

Staff warn the LDD moths are back this year and Toronto's tree canopy is in danger

Thestar.com
Jan. 6, 2022
David Nickle

Residents in neighbourhoods across the city who once again feel the gentle mist of pesticide should take heart: it’s all for the good of the trees.

Specifically, the aerial spraying contemplated for this summer is to control an expected outbreak of Lymantria dispar dispar (LDD) moths. If left unchecked, the moth larvae could defoliate trees throughout Toronto -- and affect the health of the urban tree canopy.

Some years are worse than other, and since 2007 Toronto has experienced six summers where aerial spray control measures were necessary: 2007, 2008, 2013, 2017, 2019, and 2020.

While 2021 offered some respite, data collected last year indicated that 2022 will be another bad year -- and city staff are recommending to the city’s Infrastructure and Environment Committee that it’s time to once again take to the air and spray.

Staff are recommending spending a total of $818,608 with Zimmer Air Service Inc. to spray two pesticides. In larger outbreak areas, they are recommending using Foray 48B (Btk), containing the active ingredient Bacillus thuringiensis subspecies kurstaki (btk).

In High Park, they are recommending a more aggressive and costly approach -- spraying BoVir, which contains the active ingredient Lymantria dispar Nucleopolyhedrovirus.

The use of BoVir will require emergency regulation as it’s not currently approved for use in Canada -- but staff say it’s necessary in High Park, because Foray 48B may also destroy other species of moths. BoVir uses a virus that specifically targets the LDD larvae.

The Foray 48B (Btk) pesticide will be sprayed in Wards 6, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 and 25.

The plan is going before the Jan. 11 meeting of Toronto’s Infrastructure and Environment Committee.