Saturday, September 30, 2023
September 30, 2023

Editorial: Mapping and trapping spongy moths

Salt Spring Island has unfortunately gained notoriety on the environmental front recently, but not for a positive program or achievement.

The Canadian Food Inspection Agency puts out green tent traps containing female spongy moth pheromones annually to detect the presence of the invasive moths, with the males enticed into the traps by the scent. Until last year on Salt Spring the low numbers of trapped moths were not of particular concern. But a jump from three in 2020 to six in 2021 and then 16 in 2022 — combined with a significant rise in numbers in other parts of the province — have prompted the first steps of an eradication plan to be taken.

Members of the provincial Spongy Moth Technical Advisory Committee and staff from member government agencies and the non-profit Invasive Species Council of B.C. held an open house at Fulford Hall on June 7 to bring the community up to speed about the need and plan to address the increasing population. The spongy moth caterpillar’s appetite is huge and they’re not too fussy, with oaks (including Garry oaks), arbutus, alders, apples, pears, roses and willows among the list of favoured trees and shrubs. The species is not yet considered “established” in B.C., as eradication efforts have so far been successful.

But the sense of alarm about the numbers from last year, while measured, was palpable among presenters at the Fulford Hall event. A resident couple who had dealt with an infestation in Ontario added to the discussion, stressing the devastation to trees they witnessed was incredible.

Back in 2006, a large volunteer corps was organized to put out traps and look for egg masses in the Lee Road area of Salt Spring in order to prevent the overhead spraying of the biological insecticide Bacillus thuringiensis kurstaki (Btk). Ground spray was eventually used to control an outbreak as well.

Looking for spongy moth egg masses might not sound like a ton of fun, but hopefully everyone — especially in the Vesuvius-St. Mary Lake area shown in the map accompanying the Driftwood’s June 21 story — will take the time to look for egg masses lodged on or in vehicles, boats, sheds, flower planters or trees. Reports of caterpillar or moth sightings are welcomed as well, but the moths, especially, are not as easy to be seen or identified.

Detailed information about spongy moths and eradication can be found on the B.C. government and Invasive Species Council of B.C. websites.


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