Painted lady butterflies migrate long distances in autumn across the Sahara to take advantage of food availability in the tropical savannah

Isotopic analysis indicates long-distance movements of painted lady butterflies exceeding 4000 km from Europe to Africa.

• The painted lady butterfly migrates annually between Europe and North Africa, particularly to exploit seasonal resources.
• Isotopic composition analysis of butterflies from 14 countries supports the hypothesis of long migratory flights.
• Migrants collected south of the Sahara predominantly originated from Europe, with some also coming from the Sahel.
• The findings suggest that autumn migration includes not only northwestern Africa but also southward and northward flights across the Sahara.
• This migratory behavior integrates a highly seasonal region into the life cycle of Vanessa cardui.

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