NEW YORK — Trillions of insects migrate across the globe each year, yet little is known about their journeys. German scientists set out to find clues by flying small trackers onto giant moths to follow them.
To the researchers’ surprise, the moths seemed to have a strong sense of where they were going. In a study, scientists found that even when winds change, the moths remained on the same course. This was reported by the researchers in a study, published in Science ..
Their flight patterns suggest that these moths of death’s head are skilled navigators, contrary to earlier beliefs about insects being wanderers.
” For many, many decades, we believed that insects migrate mainly by wind, which they were doing for many years.” said Myles Menz (a leading author at James Cook University, Australia).
Because of the small size of insects, it’s difficult for scientists to see how they travel. Menz stated that this is partly why it has been so hard for them to study their movements. The kinds of radio tags used to follow birds can be too heavy for smaller fliers.
But transmitters have gotten tinier. And it helps that the death’s-head hawk moth is huge compared to other insects, with a wingspan up to 5 inches (127 millimeters).
The iconic species — dark colored with yellow underwings and skull-like markings — was able to fly well with the tiny tracker glued to its back, said Martin Wikelski, a study co-author and migration researcher at Germany’s Max Planck Institute for Animal Behavior.
Moths migrate by night thousands of miles from Europe to Africa every autumn. Researchers released tagged moths from Germany to study their flight patterns towards the Alps.
Wikelski, the study’s pilot, took off in his plane, circling the area and waiting for any moths on the move. If he did pick up a signal from a tiny traveler, he would follow its radio blips for hours at a time.
“The little moth is guiding you,” he said.
The researchers followed the flight paths of 14 moths, with their longest track around 56 miles (90 kilometers).
Not only did the moths fly in straight lines, but they also seemed to work around wind conditions, Menz said, flying low to the ground when the winds were against them, or rising up to catch a helpful tail wind.
Though the number of moths tracked was fairly small, getting any close-up look at insect migration is significant, said Ryan Norris, an insect and bird migration researcher at the University of Guelph in Canada, who was not involved in the study.
” I was amazed at the distance they were able to track them,” Norris stated. “And it certainly is surprising that individual moths stay on this straight trajectory.”
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