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Year of the Bogong

This spring, swarms of endangered Bogong moths turned up in homes and gardens across south-east Australia.

A brown Bogong moth resting on a black tarp, wings folded, with a dark dash and pale spots on each wing
A Bogong moth sheltering under a tarp in a Sydney backyard, October 2026.

Each year, nature lovers share their photos on the iNaturalist app, and scientists use them as crowdsourced field work, mostly to map where animals and plants live.

Each dot is a Bogong someone photographed this spring.

Keep scrolling to move through the days

Out of all the moths people photographed, Bogongs stood out most in the Blue Mountains and the Illawarra, with Sydney and the South Coast close behind.

Around Sydney, people have photographed 1,728 Bogongs so far this spring. In previous years, Bogongs made up fewer than 1 in 40 moths photographed there. So why are we seeing so many?

To answer that, let's start with where Bogongs live and how they migrate. They breed over winter on the inland plains. Each spring they fly up to 1,000 km to cool caves in the Snowy Mountains and Victoria's high country, navigating on instinct by the stars and the Earth's magnetic field.

This autumn and winter, rain over the breeding grounds was a third above average. Bogong caterpillars live in the soil there and feed on the plants that come up after rain, so the moths likely had a baby boom of sorts.

Weather data by Open-Meteo.com

So how did they end up in Sydney, when it's not on their flight path? Experts think strong north-westerly winds blew many off course towards the coast, and then city lights drew them down into our homes.

Weather data by Open-Meteo.com

Bogong share near you

Are you seeing more Bogongs than usual? Type a NSW postcode to see how your area compares.

The 15 areas with the highest share, of those with at least 100 moths photographed in spring 2026
AreaBogongs per 100 moths, spring 2026Springs 2020 to 2025People logging Bogongs

Each area is a square about 100 km across, named after its largest town.

Still endangered

The drought from 2017 crashed the population. A 2021 study found that mountain caves which once held hundreds of thousands of Bogongs were down to a handful of moths. The IUCN listed the Bogong as endangered that same year.

This spring's swarms are a hopeful sign, but nobody has counted how many moths made it.

If Bogongs turn up at your place, Zoos Victoria's Marissa Parrott suggests switching off outdoor lights, keeping cats inside and gently ushering any moths back out. They won't stay long. They have mountains to get to.

References