29/09/2026
Rejoice not spray !
Right now, across Sydney, the Hawkesbury, the Illawarra and the South Coast, millions of small brown moths are clinging to walls, circling streetlights and getting into houses. Social media is full of people losing their minds about it.
We understand. Truly.
But before you reach for the spray, there is something you need to know about what is happening outside your window.
These are Bogong moths. And a few years ago, they almost disappeared entirely.
Before 2017, around four billion of them made this journey every spring. Then came the drought. Researchers went up to the alpine caves where the moths shelter through summer — walls that had been carpeted with them, thousands packed into every square metre — and found them essentially empty.
The population crashed by an estimated 99.5 per cent.
In December 2021 the Bogong moth was added to the international Red List as endangered. A creature so common that it once blotted out the stars over Australian towns was suddenly a species in trouble.
So when people tell you there are too many moths this year, understand what they are actually describing. They are describing a return.
What this little moth actually does
It weighs about a third of a gram. Less than a Tic Tac. It is between 25 and 35 millimetres long.
And every spring it flies up to 1,000 kilometres — from breeding grounds in inland Queensland, New South Wales and Victoria, all the way to the Australian Alps — navigating at night using the stars and the earth's magnetic field. It has never made the trip before. Nothing taught it the way.
Along the route it feeds on native flower nectar and pollinates as it goes.
And when it reaches the mountains, it becomes dinner.
The mountain pygmy-possum is critically endangered. There are very few left. It wakes from months of hibernation under the alpine snow, starving, with young to raise — and it survives on these moths. Fat-rich, protein-rich, arriving exactly when they are needed.
When the moths collapsed in 2017 and 2018, more than half of the possum mothers in some alpine areas lost their litters.
That is what a moth plague means. It means a tiny possum in the Snowy Mountains might get through another spring.
What you can do tonight
Turn off any outdoor lights you don't need. The lights are the whole problem — they pull exhausted moths off course and trap them in suburbs instead of letting them reach the mountains.
Don't spray them. They are completely harmless to humans.
If one is inside, cup it gently and put it out. Catch, don't squish.
And if you see them, photograph them and log them on Zoos Victoria's Moth Tracker. Scientists are using those sightings to work out how many are making it to the Alps this year. Your annoying balcony moth is data.
One last thing
For tens of thousands of years, Aboriginal peoples travelled to the high country when the moths arrived, gathering at the aestivation sites for feasting and ceremony. These moths have been part of the story of this continent for a very, very long time.
They will be gone in a few weeks.
Give them a nod on the way through.
Are they at your place? Post a photo in the comments and tell us whether you're team "get them out" or team "let them pass". 🦋🏔️🇦🇺
Credit: Seven News, Patrick Burns, September 2026.
Sources: Zoos Victoria Moth Tracker; IUCN Red List (endangered, December 2021); Royal Society of Victoria, Science Victoria; Mongabay, August 2026.
