skull moth
Moths are smart long-haul fliers
A skull butterfly with a transmitter. photo
© Christian Ziegler/Max Planck Institute for Animal Behavior/dpa
For the first time, researchers track insects for more than 80 kilometers in an airplane. They found that the animals can navigate much more nimbly than was previously known.
According to researchers, some insects are as proficient long-range fliers as birds. An international team equipped moths with transmitters and tracked them over a distance of up to 80 kilometers with a light aircraft.
This is the longest distance an insect has ever been observed in the wild, explains ecologist Martin Wikelski, who conducts research at the Max Planck Institute for Behavioral Biology and at the University of Konstanz. Previous detailed studies on insect movement were conducted over a maximum of one to two kilometers.
Up to 4000 kilometers
According to the researchers, the studied squirrel butterflies (Acherontia atropos) cover a total distance of up to 4000 kilometers on their migration between Europe and Africa. The study was published in the journal “Science” and proves that the moths use advanced flight strategies to adapt to prevailing wind conditions and thus accurately maintain their flight direction over long distances.
Insects are usually too numerous to notice and find and too small to carry tracking devices, explains first author Myles Menz, who worked at the Max Planck Institute during the research. For their study, however, the researchers equipped the squirrel butterfly, which is extremely large for an insect and weighs 3.5 grams, with a radio transmitter that weighs only 0.2 grams. With an airplane and an antenna attached, they followed the moths from Constance to the Alps.
The records show that the moths did not wait for the wind to favor them. Instead, they used different flight strategies to adapt to prevailing wind conditions and stay on course all night. So when the wind was favorable, they flew high so that they were supported by the wind. In contrast, in strong headwinds or crosswinds, they flew low and increased their speed to stay on course.
Real navigation experts
For years, it was believed that insects were mainly driven by the wind during long-distance migration, Menz said. “However, we have been able to show that insects can be real navigation experts, on par with, for example, birds, and that they are much less vulnerable to adverse wind conditions than we thought.”
In follow-up research, the researchers now want to investigate how the moths manage to fly in a straight line. Based on previous lab work, there’s some chance the insects are using internal compasses, both visual and magnetic, to map their global flight paths, Menz explained.