Why the spongy moth outbreak has vanished in Québec

By Emma Despland
October 24, 2022
Category: Forestry
Region: Canada, Canada East

Last year, forests across southern Québec and Ontario and much of New England turned eerily leafless. The air hummed with the sound of munching mandibles and tree trunks were covered with a writhing carpet of caterpillars, while showers of caterpillar poop fell softly on the heads of unsuspecting hikers and campers. The population of the European spongy moth reached a dramatic peak in 2021 and completely vanished this year. In 2020, the hungry caterpillar damaged 583,157 hectares of forests in Ontario and this number is bound to go up when the 2021 numbers are revealed. …However, these outbreaks always come to an end because of what ecologists call lagged-density dependent population dynamics. …The outbreak crashes when the insect mortality eventually catches up with its population size. This usually happens due to a combination of factors including low food supply and increase in predators.

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