The Bogong moths of Australia have been identified as the first insects that can see the Earth's magnetic field, an ability that helps them navigate at night in long-distance migrations covering over 600 miles.
The insects use the magnetic field as a compass to keep them on the right path, as they migrate to very specific locations in Australia. The discovery follows reports of birds navigating long distances by using magnetic fields that they can see through a special protein in their eyes, and turtles being reunited with others of similar genetic composition through magnetic fields.
Bogong Moths Use The Earth's Magnetic Field
Every spring, millions of Bogong moths in Australia go on a 600-mile journey to the Australian Alps, which is the highest mountain range in the country. The nocturnal insects rest during daytime and travel during nighttime until they reach the Alps. Once there, the Bogong moths hide in caves to escape the heat of summer.
After a few months, the Bogong moths fly out of the caves and make their way back to where they came from. Once they are home, they mate and spawn a new generation before dying. The babies then continue the cycle in the next spring.
Scientists had no clue how the Bogong moths, that have no memory of the Alps, are able to travel to the specific location of the caves even if they come from different parts of Australia. New research, however, determined that the insects use the Earth's magnetic field for their journey.
In a report published in the Current Biology journal, a team of scientists from Australia and Sweden claimed that the Bogong moths use the Earth's magnetic field as a compass so that they will stay on the right path to the caves in the Alps.
The Bogong moth is just one of two insects who make long migrations to very specific locations, the other being the monarch butterfly. The moths, upon starting their journey, find their bearings and follow landmarks, while often recalibrating their route toward their destination.
Bogong Moths In Flight Arenas
Using what they called "flight arenas," the scientists were able to prove that Bogong moths can detect magnetic fields.
The flight arenas were cylinders that were surrounded by magnetic coils. The scientists manipulated the coils to change the direction of the magnetic field that they generate.
Simply changing the direction of the magnetic field did not have an effect on the insects though. The scientists eventually figured out that the Bogong moths, like many nocturnal insects, have excellent vision. When visual cues in the form of black triangles were placed at the side of the cylinder and aligned with the direction of the magnetic field, the Bogong moths responded as expected.
When the scientists left the visual cue in place but adjusted the magnetic field, the insects became confused, providing strong proof that the Bogong moths had a magnetic sense.