Meet the moths that use the stars to find their way
TWICE A YEAR the skies of south-eastern Australia fill with billions of Bogong moths. In the spring these unassuming brown critters, about an inch long, fly south from their birthplace in Queensland or New South Wales to the Australian Alps where they enter a months-long hibernation-like state in the cool mountain caves. In the autumn, they fly the 1,000km-long return leg to breed.
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Int'l Business Times
5 hours ago
- Int'l Business Times
Moth Uses Stars To Navigate Long Distances, Scientists Discover
A species of Australian moth travels up to a thousand kilometres every summer using the stars to navigate, scientists said Wednesday, the first time this talent has been discovered in an invertebrate covering vast distances. When temperatures start rising every year, Bogong moths embark on the long night-time flight from their home on the country's eastern coast to the cool inland shelter of caves in the Australian Alps. It has recently been discovered that they can use Earth's magnetic field like a compass to stay on track during their trip of up to 1,000 kilometres (620 miles). Now, a study published in the journal Nature has found that the moths can also use the light from the stars and the Milky Way to find their way through the dark. "This is the first invertebrate that's known to be able to use the stars for that purpose," study co-author Eric Warrant of Sweden's Lund University told AFP. The only other invertebrate known to use stars for orientation are dung beetles -- but that is over very short distances, Warrant said. Out of all the animal kingdom, only some birds, possibly seals and of course humans can use starlight to navigate long distance. Bogong moths, which are around three centimetres long and are named after the Indigenous Australian word for brown, now join that list. To study this phenomenon, the international team of researchers put some Bogong moths in a small enclosure and projected different maps of the night sky onto its ceiling. The moth was tethered to a rod connected to the top of the enclosure, which precisely recorded which directions it tried to fly in. This "flight simulator" first confirmed that Bogong moths can in fact navigate using their internal magnetic compass, lead study author David Dreyer, also of Lund University, told AFP. Then the researchers removed the effect of Earth's magnetic field in the enclosure. "To our surprise," the moths were still able to find the right direction, Dreyer said. When they rotated the sky 180 degrees, the moths changed their flight to follow along. And when the researchers projected weird, incorrect maps of the night sky, the moths became erratic and lost. This reinforced that the insects can not only navigate by the sky, but can follow along during the night when the relative positions of the stars shift along with Earth's rotation. No one knows exactly how the Bogong moth manages this feat. One theory is that they sometimes "cross-check" their direction with their magnetic compass, Dreyer said. Another question is exactly which stars the moths are using to navigate. In the lab, the researchers monitored 30 neurons involved in the moth's vision, coordination and navigation. Developing the system of non-magnetic electrodes "cost me a fortune but it was worth the investment," Warrant said. The neurons became particularly active at the sight of the long, bright stripe of the Milky Way, as well as the Carina Nebula. The Milky Way is brighter in the Southern Hemisphere than in the north, Warrant pointed out. "The intensity of that stripe grows as you go from the northern part of the sky to the southern part," which could offer a clue as to how the moths use it to navigate south, Warrant said. Another mystery is how the moths know when to head south when summer arrives. Warrant, who is supervising further research on this subject, said one option is that this knowledge was simply "something that the parents hand to their children". The researchers believe that near the end of the moth's long migration, they start noticing clues they are getting close to their mountain refuge. Warrant said he has identified a specific "odour compound" which emanates from the caves. This smell "seems to act as a navigational beacon right at the very end of the journey," he added. After the moths have seen out the sweltering summer, they return to their coastal birthplace to reproduce before dying. Bogong moths are named after the Indigenous Australian word for brown AFP
France 24
6 hours ago
- France 24
Moth uses stars to navigate long distances, scientists discover
When temperatures start rising every year, Bogong moths embark on the long night-time flight from their home on the country's eastern coast to the cool inland shelter of caves in the Australian Alps. It has recently been discovered that they can use Earth's magnetic field like a compass to stay on track during their trip of up to 1,000 kilometres (620 miles). Now, a study published in the journal Nature has found that the moths can also use the light from the stars and the Milky Way to find their way through the dark. "This is the first invertebrate that's known to be able to use the stars for that purpose," study co-author Eric Warrant of Sweden's Lund University told AFP. The only other invertebrate known to use stars for orientation are dung beetles -- but that is over very short distances, Warrant said. Out of all the animal kingdom, only some birds, possibly seals and of course humans can use starlight to navigate long distance. Bogong moths, which are around three centimetres long and are named after the Indigenous Australian word for brown, now join that list. 'Flight simulator' To study this phenomenon, the international team of researchers put some Bogong moths in a small enclosure and projected different maps of the night sky onto its ceiling. The moth was tethered to a rod connected to the top of the enclosure, which precisely recorded which directions it tried to fly in. This "flight simulator" first confirmed that Bogong moths can in fact navigate using their internal magnetic compass, lead study author David Dreyer, also of Lund University, told AFP. Then the researchers removed the effect of Earth's magnetic field in the enclosure. "To our surprise," the moths were still able to find the right direction, Dreyer said. When they rotated the sky 180 degrees, the moths changed their flight to follow along. And when the researchers projected weird, incorrect maps of the night sky, the moths became erratic and lost. This reinforced that the insects can not only navigate by the sky, but can follow along during the night when the relative positions of the stars shift along with Earth's rotation. Mysteries abound No one knows exactly how the Bogong moth manages this feat. One theory is that they sometimes "cross-check" their direction with their magnetic compass, Dreyer said. Another question is exactly which stars the moths are using to navigate. In the lab, the researchers monitored 30 neurons involved in the moth's vision, coordination and navigation. Developing the system of non-magnetic electrodes "cost me a fortune but it was worth the investment," Warrant said. The neurons became particularly active at the sight of the long, bright stripe of the Milky Way, as well as the Carina Nebula. The Milky Way is brighter in the Southern Hemisphere than in the north, Warrant pointed out. "The intensity of that stripe grows as you go from the northern part of the sky to the southern part," which could offer a clue as to how the moths use it to navigate south, Warrant said. Another mystery is how the moths know when to head south when summer arrives. Warrant, who is supervising further research on this subject, said one option is that this knowledge was simply "something that the parents hand to their children". The researchers believe that near the end of the moth's long migration, they start noticing clues they are getting close to their mountain refuge. Warrant said he has identified a specific "odour compound" which emanates from the caves. This smell "seems to act as a navigational beacon right at the very end of the journey," he added. After the moths have seen out the sweltering summer, they return to their coastal birthplace to reproduce before dying. © 2025 AFP
Perth Now
6 hours ago
- Perth Now
Starry nights light the way for Bogong moth migration
Billions of Bogong moths emerge from breeding grounds in Australia's southeast and take to the skies each year, navigating up to 1000 kilometres to reach a place they have never been before. Guided by the stars and the glow of the Milky Way, these nocturnal insects embark on their annual spring migration to a few select caves in the Australian Alps, where they seek refuge from the summer heat. Just months later, in autumn, they make the return journey to breed, after which they die. New research published in the journal Nature on Thursday is shedding light on one of nature's great migratory mysteries, involving the incredible journey of four billion moths each year. Professor Eric Warrant, who researches nocturnal vision in insects at Sweden's Lund University, said while it is known that some birds and even humans use stars to find their way over long distances, this was the first time it had been proven that an insect can do it too. "Bogong moths are incredibly precise," he said. "They use the stars as a compass to guide them over vast distances, adjusting their bearing based on the season and time of night." Scientists made the discovery after using special flight simulators to record moth brain activity in controlled environments. They tested how moths find their way under different sky conditions. When the moths saw a normal starry sky and there was no magnetic field, they flew in the direction of the season, south in spring and north in autumn. When the starry sky was flipped upside down, the moths changed direction to match. But when the stars were scrambled, the moths appeared to get confused and failed to fly in any specific direction. "This proves they are not just flying towards the brightest light or following a simple visual cue," Prof Warrant said. "They're reading specific patterns in the night sky to determine a geographic direction, just like migratory birds do." The Australian Bogong moth, which can fit in the palm of a hand, has seen a sharp decrease in population over the past years, with the insect deemed vulnerable. The insects are often found in Australia's south, and were once a source of food for First Nations people. Researchers said the study highlighted the importance of protecting migratory pathways and the dark skies that the moths rely on. "This is not just about a moth, it's about how animals read the world around them," Prof Warrant said. "The night sky has guided human explorers for millennia. Now we know that it guides moths, too."
