In a world-first discovery, researchers have shown that Australia's iconic Bogong moth uses constellations of stars and the Milky Way to navigate hundreds of kilometres across the country during its annual migration – making it the first known invertebrate to rely on a stellar compass for long-distance travel.
The landmark study, published today (Thursday 19 June) in Nature, reveals how this unassuming nocturnal moth combines celestial navigation with Earth's magnetic field to pinpoint a specific destination it has never visited before: the cool alpine caves of the Snowy Mountains, where it hibernates for the summer.
Led by an international team of scientists from Lund University , the Australian National University (ANU), the University of South Australia (UniSA) and other global institutions, the research sheds new light on one of nature's great migration mysteries, involving approximately four million moths each year.
"Until now, we knew that some birds and even humans could use the stars to navigate long distances, but this is the first time that it's been proven in an insect," says Lund University Professor of Zoology, Eric Warrant , who is also a Visiting Fellow at the ANU and an Adjunct Professor at UniSA.
"Bogong moths are incredibly precise. They use the stars as a compass to guide them over vast distances, adjusting their bearing based on the season and time of night."
Each spring, billions of Bogong moths (Agrotis infusa) emerge from breeding grounds across southeast Australia and fly up to 1000 kilometres to a small number of caves and rocky outcrops in the Australian Alps.
The moths lie dormant in the cool, dark shelters throughout summer, and in autumn make the return journey to breed and die.
Using sophisticated flight simulators and brain recordings in controlled, magnetically neutral environments, the researchers tested how moths orient themselves under different sky conditions.
When presented with natural starry skies and no magnetic field, they consistently flew in the correct migratory direction for the season – southward in spring, northward in autumn.
When the starry skies were rotated 180 degrees, the moths reversed direction accordingly, but when the stars were scrambled, their orientation vanished.
"This proves they are not just flying towards the brightest light or following a simple visual cue," says Prof Warrant. "They're reading specific patterns in the night sky to determine a geographic direction, just like migratory birds do."
Interestingly, when stars were obscured by clouds, the moths maintained their direction using only the Earth's magnetic field. This dual compass system ensures reliable navigation even in variable conditions.
The team also delved into the neurological basis of this behaviour, identifying specialised neurons in the moth's brain that respond to the orientation of the starry sky. These cells, found in brain regions responsible for navigation and steering, fire most strongly when the moth is facing southwards.
"This kind of directional tuning shows that the Bogong moth brain encodes celestial information in a surprisingly sophisticated way. It's a remarkable example of complex navigational ability packed into a tiny insect brain."
Researchers say the discovery could inform technologies in robotics, drone navigation, and even conservation strategies for species threatened by habitat loss or climate change.
Bogong moth populations have declined sharply in recent years, promoting their listing as vulnerable.
The study underscores the importance of protecting migratory pathways and the dark skies these moths rely on.
"This is not just about a moth ̶ it's about how animals read the world around them," says Prof Warrant. "The night sky has guided human explorers for millennia. Now we know that it guides moths, too."
Co-author Professor Javaan Chahl , a remote sensing engineer from the University of South Australia, made headlines in August 2024 using the discoveries from a previous study led by Lund University involving dung beetles, who use the Milky Way as a reference point to roll balls of dung in straight lines. Prof Chahl's team modelled the same technique used by dung beetles to develop an AI sensor for robot navigation in low light.
The Nature paper 'Bogong moths use a stellar compass for long-distance navigation at night' is authored by researchers from Europe, the UK, China, Australia, Canada and Australia. DOI: 10.1038/s41586-025-09135-3
A video produced by the Australian Academy of Science
