Untreated lymantria moth populations can cause significant damage to forests, farms, orchards and urban trees. (File photo)

Untreated lymantria moth populations can cause significant damage to forests, farms, orchards and urban trees. (File photo)

Spraying planned for 402 hectares in Lake Cowichan to combat invasive moths

Moth spraying planned for 402 hectares in Lake Cowichan

The B.C. government will conduct aerial moth spray treatments in Lake Cowichan beginning in early May.

According to the B.C. Ministry of Forests, the treatments will prevent lymantria moths, (formerly known as gypsy moths), from becoming established and to minimize the risk they pose to forests, farms, orchards and urban trees.

About 402 hectares in Lake Cowichan will be sprayed along with 50 hectares in View Royal and 1,068 hectares in Nanoose/Lantzville/Nanaimo.

The ministry said “trapping and monitoring results from 2021 show clear evidence that lymantria moth populations have increased dramatically in the areas slated for treatment this spring, likely as a result of outbreaks in Ontario and Quebec during the past three years. Egg masses are commonly transported to B.C. on recreational vehicles and outdoor household articles originating from affected areas outside of the province.”

Left untreated, the invasive moths could spread to other areas of the province and affect trees such as Garry oak, arbutus, red alder, aspen, cottonwood, maple, orchard fruit trees, nut trees and many species of urban ornamental trees, well as food crops such as apples, blueberries and other fruits.

As many as four applications of Foray 48B will be sprayed in the specified areas beginning in early May and ending in early June.

“Organic farms in the spray area treated with Foray 48B will not lose their organic certification. The active ingredient, Bacillus thuringiensis var kurstaki (Btk), is naturally present in urban, agricultural and forest soils throughout the province. It affects only the stomachs of caterpillars (e.g., lymantria moth caterpillars) and is specific to their digestive systems,” said the ministry. “Btk has been approved for the control of lymantria moth larvae in Canada since 1961. It does not harm humans, mammals, birds, fish, plants, reptiles, amphibians, bees, or other insects. It only affects lymantria moth caterpillars after they have ingested it.”

Lake Cowichan