Bogong moths recover after decades of decline

People across eastern Australia have observed a large increase in bogong moth populations this year.

For decades, the moths declined, falling to levels described as “undetectable” in the Australian Alps after a major crash in 2017. Ecologists believe drought conditions from 2017 to 2019 were the primary cause of the population drop, with pesticides and light pollution contributing to earlier, slower declines.

Citizen scientists are now collecting data on the moth revival through the Bogong Watch project on the iNaturalist platform, showing a clear increase in sightings. Bogong moths once numbered in the billions and were known to gather at events like the 2000 Sydney Olympics and invade buildings in Canberra. The return of the moths benefits plants they pollinate and endangered species like the mountain pygmy possum that depend on them for food.

While formal surveys are still underway, the surge in observations indicates a positive trend for the species.