Insecticide treatments happening over Vancouver Island to control invasive moths

Insecticide treatments happening over Vancouver Island to control invasive moths
Photo credit: Government of B.C.

The B.C. government plans to conduct invasive spongy moth treatments over Vancouver Island this spring, including Greater Victoria, to curb areas of the insect that’s harmful to ecosystems and the economy, officials say.

Once established, invasive spongy moths, also known as Lymantria moths and formerly known as gypsy moths, feed on trees like Garry oak, arbutus and red alder and compete with local pollinators, according to B.C.’s Ministry of Forests.

The ministry says that left untreated the moths can spread to other areas of the province and, along with urban trees, pose a risk to forests, farms and orchards, as experienced in Ontario and the eastern United States in recent years.

“Agricultural operations are at risk from spongy moths because the moths can affect food crops, such as apples, blueberries and other fruits, as well as garden nursery products,” the ministry said in a release.

“Infested operations are often subject to agriculture quarantines, as well as additional measures that may include product certification and increased pesticide use.”

In addition to the Capital Region, including in Esquimalt and View Royal, the treatments are planned for Port Alberni, Courtenay and Campbell River and will take place between April 1 and June 30.

Crews will use a biological insecticide called Foray 48B with the active ingredient Bacillus thuringiensis var kurstaki (Btk), which is naturally present in urban, agricultural and forest soils throughout the province.

The treatment, first approved in Canada in 1961, only affects spongy moth caterpillars as it’s specific to their digestive systems, the ministry says, meaning there’s no threat to humans or mammals and insects like birds, fish and bees.

“Anybody who’s gardened, played outdoors or spent any time on the ground has come in contact with this bacteria,” said Dr. Richard Stanwick, Island Health’s former chief medical health officer, in a 2017 video about scientific studies and safety protocols regarding Foray 48B.

“The CRD and Capital Health Region conducted significant studies at the time of a spray in 1999, that involved us monitoring not only individuals in the spray zone but individuals outside the spray zone. We were able to show, conclusively, that there were no medically significant differences between the populations, including that of the children.”  

The product could cause minor irritation to the eyes, ears, nose and throat, Stanwick says, adding, “people who don’t want to be exposed, the best thing to do is when a spray is taking place, remain indoors for an hour with your doors and windows closed.”

The ministry says that in 2022, a monitoring program trapped a record number of male spongy moths throughout B.C., with an increase over the past two to three years across sites identified for treatment. 

“This indicates that spongy moths could become established in those locations if the planned pesticide spraying is not completed. The increased threat potential is tied to outbreaks in Ontario and Quebec during the past three years,” officials added.

“Egg masses are commonly transported to B.C. on recreational vehicles and outdoor household objects originating from affected areas outside of the province.”

The ministry is inviting residents in the planned spray areas to submit comments for evaluation about a treatment application amendment for Courtenay, as well as pesticide-use permit applications for Victoria, Port Alberni and Campbell River, by Feb. 21, with more details found here.

Ethan MorneauEthan Morneau

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