Painted ladies are one of the most widely distributed butterflies and can be found on all continents except Antarctica and South America. The species of butterflies is a resident of warmer areas, migrating in the fall towards more favorable climates. Each fall, large populations of Painted Lady butterflies (Vanessa cardui) migrate from Europe to subtropical Africa, with individuals traveling up to 4,000 kilometers. This species of butterfly makes the longest single-leg migratory flight of all known butterfly migration routes.
A recent study published in the Royal Society looked at isotopic evidence that some individual Painted lady butterflies make a reverse migration back to Southern Europe in the spring. While a reverse migration has been suspected, this is the first study to try and definitely shows that Painted lady butterflies migrate back to Europe from Africa. In this study, researchers looked at hydrogen isotope values present on Painted lady butterfly wings found between February and April in Europe to determine their originations.
Talavera, G., Bataille, C., Benyamini, D., Gascoigne-Pees, M., & Vila, R. (2018). Round-trip across the Sahara: Afrotropical Painted Lady butterflies recolonize the Mediterranean in early spring. Biology letters, 14(6), 20180274.