The Thistle Vanessa butterfly, commonly known as the Beautiful Lady, is a very common butterfly in Europe in spring and summer. Very common but nevertheless exceptional! Weighing just a quarter of a gram, it does not hesitate to undertake a migration of several thousand kilometers. Equipped with a brain no bigger than a pinhead, it orientates itself without a hitch. Spending the winter in North Africa, the Belles-Dames are chased away in spring by the rise in temperature and by a small parasitic wasp. They will then begin a gigantic migration that will take them to the edge of the Arctic Circle.
During their entire journey, the Beautiful Ladies will follow only one guide, the Sun, which will give them the direction of the North in the spring, and the South in the fall.Their precious ally will be the wind, which they will seek out at different altitudes until they find the favorable current that will take them further North.This outward migration will take place over nearly four months, much longer than the life span of an adult butterfly. With the Belles-Dames migration, we have a surprising example of trans-generational migration. The first generation of butterflies will begin the migration, then reproduce en route and make way for their descendants.
These young butterflies will then in turn take the northern route, attracted by the increasingly long days in northern Europe in summer.Their return migration has long remained a complete mystery to scientists. No one had ever seen Belles-Dames going the opposite way in autumn, to reach North Africa. And this lack of observation had even led some researchers to think that the butterflies that had arrived at the end of their migration to Northern Europe in the summer died there in the autumn, surprised by the cold.The design and development of entomological radars have shown that this was not the case in reality. The design and development of entomological radars showed that this was not the case.
And the use of these radars showed that these migratory butterflies did return to the Sahel in autumn. Millions of them, but at an altitude of four to five hundred meters, totally invisible to the observer at ground level. The veil is lifted on the mysteries of this long-distance traveler
. A butterfly engaged in one of the longest migrations of insects ever recorded.
Partner(s) : Curiosity Stream, Ushuaïa TV, du CNC, et du programme Europe Creative de l'Union Européenne.
Broadcaster(s) : ARTE, RTBF, Curiosity Stream
Director(s) : Alexis de Favitski
Year : 2019
Duration : 43 minutes
