A first-of-its-kind study reveals that migrant insects can travel in perfectly straight flight paths

According to the release, the tagged moths were then released, and the researchers waited for the flight to begin, after which they chose a single insect to follow. They followed 14 moths each for up to 80 kilometers or 4 hours—a stretch long enough to be considered migratory flight—using antennas mounted on a Cessna airplane to detect precise locations every five to 15 minutes. Insects were followed in the south-south-west direction from Konstanz into the Alps, which follows the route taken by hawkmoths towards the Mediterranean and Northwest Africa.

A first-of-its-kind study reveals that migrant insects can travel in perfectly straight flight paths

Hawkmoth being caught in the Swiss Alps

Flying in an aircraft does involve constraints, so the scientists tracked the moths continuously until the insects stopped. “When you’re in an airplane, it becomes challenging to wait for the insects to begin migrating again because you would have to be in the air when this happens, which could be anytime in the night,” says senior author Martin Wikelski, a movement ecologist from the MPI-AB and the University of Konstanz, who piloted the plane during the study.

The moths maintained straight trajectories for long distances during flight. Rather cleverly, they employed flight strategies to buffer against winds, which allowed them to hold their course throughout the night.

“For years, it was assumed that insect migration was mostly about getting blown around. But we show that insects are capable of being great navigators, on par with birds, and are far less vulnerable to wind conditions than we thought. By showing that it is technically possible to continuously monitor individual insects over migration and to observe their flight behavior in detail, we hope to inspire more studies to answer many more big questions in this area,” said Menz.

The authors intend to answer the question of how moths can maintain such straight lines. “Based on past lab work, it’s possible that the insects are using internal compasses, both visual and magnetic, to chart their way around the world,” added Menz.

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