The B.C. government plans to conduct aerial spray treatments in three Vancouver Island locations this spring to prevent invasive Lymantria moths from becoming established and damaging forests, farms, orchards and urban trees.
The province said Lymantria moth populations (formerly known as gypsy moths) increased dramatically last year, based on trapping and monitoring results.
The B.C. government attributed this increase to egg masses transported on recreational vehicles and outdoor household articles from affected areas outside of the province, such as Ontario and Quebec.
The pests pose a threat to trees such as Garry oak, arbutus, red alder, aspen, cottonwood, maple, orchard fruit trees, nut trees and many species of urban ornamental trees, as well as food crops such as apples and blueberries.
The Ministry of Forests, Lands, Natural Resource Operations and Rural Development plans to apply Foray 48B, an insecticide used to selectively kill larval moths and butterflies, between April 15 and June 30, in the following areas:
-View Royal (50 hectares south of Thetis Lake Regional Park and the Trans-Canada Highway);
-Nanoose Bay (1,068 hectares south of Nanoose Bay to the northern boundary of the City of Nanaimo);
-Cowichan Lake (402 hectares at the easternmost tip of the lake and part of the Town of Lake Cowichan).
Foray 48B is used in organic farming and the active ingredient, Bacillus thuringiensis var kurstaki (Btk), is naturally present in urban, agricultural and forest soils throughout the province, according to the ministry. It only affects the stomachs of caterpillars, such as Lymantria moth caterpillars, and is specific to their digestive systems.
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, according to the ministry. It only affects Lymantria moth caterpillars after they ingest it.
The Ministry of Forests, Lands, Natural Resource Operations and Rural Development applied for an amendment to its existing pesticide use permit, issued in March 2021 for Lymantria moths.
Residents in the planned spray areas are invited to submit comments about this application to amend the existing pesticide use permit (refer to Permit No. 738-0032-21/24) for evaluation by the Integrated Pest Management Act administrator, Ministry of Environment and Climate Change Strategy, Suite 200-10470 152 St., Surrey, B.C. V3R 0Y3, by March 12.
The planned treatments are in addition to five areas in the Fraser Valley and the Lower Mainland. Last year’s monitoring program trapped 98 male moths in these eight areas, indicating that the moths could become established if the proposed pesticide spraying is not done.