BC government pauses aerial spray program for moths in Kamloops, Okanagan

The government has been spraying a chemical from the air in Kamloops, the Okanagan and around the province to combat the scourge of the invasive spongy moth for years, but this year the program has been deferred.

“2024 was a successful treatment year for spongy moth, so the ministry is deferring the 2025 treatment program. Ongoing monitoring will take place to manage for any future potential treatments,” the Ministry of Forests said in an email to iNFOnews.ca.

The pesticide used to attack the invasive moth species is known as BTK, or bacillus thuringiensis kurstaki, and it has been criticized by community groups like the Kelowna Citizens Safety Association, and Communities for Clean Air.

The ministry said the program deferment had nothing to do with criticism about the use of BTK, also known as Foray 48B.

“That implication is inaccurate. The program is paused for 2025 because 2024 was a successful treatment year,” the ministry statement said.

The ministry website said the chemical poses a low risk to humans, waterways and anything other than the target moth and butterfly caterpillars.

“Even though there is no evidence of harm to humans from BTK, persons with respiratory ailments or other health concerns may wish to reduce their exposure to the product during the spray operation. Close windows the evening before aerial spraying takes place and stay indoors until the BTK droplets have cleared the air, usually within 30 minutes to 1 hour, sooner in windy conditions,” the ministry said on its website.

READ MORE: iN PHOTOS: Sun rises behind plane spraying for invasive moth in Kamloops

BTK is a strain of bacteria that is found naturally in the earth and water and it is known to cause illness in insect larvae. The pesticide has been used for more than 30 years with no evidence to suggest insects develop immunity. 

The spongy moth has been known to devastate forests and defoliate residential areas in Ontario and the U.S. and there is a risk they will spread around B.C. if left untreated.

Last year, the ministry sprayed 80 hectares in Kamloops and 52 ha in West Kelowna.

The pesticide is typically sprayed from a helicopter in areas where spongy moths have been found each spring.

It’s unclear whether the program will resume next year.