L’Acherontia atropos is known to the general public for his presence on the poster of the terrifying silence of the lambs, where a specimen covers Jodie Foster’s mouth. In reality, the death’s-head sphinxes, a charming nickname inherited from the human skull-shaped spot that these moths sport on their backs, are great travelers who travel, each autumn, thousands of kilometers from Europe with the other shore of the Mediterranean as its destination.
Researchers from the Max Planck Institute, Germany, and the University of Exeter, Britain, have been interested in the unusual sense of orientation of this insect, reports Time. The scientists took advantage of the wingspan of the butterflies – 13 centimeters on average – which ranks them among the largest in Europe, to place high-frequency mini-transmitters on their backs in order to follow their movements. Fourteen specimens were released from Constance, in northern Switzerland.
Seven sphinxes finally began their migration and the biologists were able to follow their journey for a whole night. “The butterflies traveled south or southwest, always in a straight line for tens of kilometers, it is very surprising, and it indicates a good navigation system”, explains to the Swiss daily Myles Menz, biologist at the Max Planck Institute at the time of the experiment and author of the study published in the magazine Science August 11.
Route strategies and optimization
Myles Menz points out that the butterflies had to deal with the elements, including headwinds, and were able to devise strategies, such as flying against the trade winds at low altitude to better control their trajectory. The researchers believe that this range of techniques would serve to optimize flight speed in order to save energy during the trip.
“We believe that death’s-head hawk-moths have some kind of internal compass, based on a combination of as yet unexplained biological mechanisms, to orient themselves and stay on course.”details Myles Menz, who also suggests that these insects could use “the earth’s magnetic field” or “their very good night vision” to locate.