Every year, painted lady butterflies born in Europe embark south on an epic journey to Africa. Now, researchers know exactly where on the continent these long-haul travelers spend their winter vacation.
From December through February, after flying across the Sahara in the fall, the orange-and-brown-winged insects set up camp and breed in savannas and highlands across central Africa, scientists report April 10 in the Proceedings of the National Academy of Sciences. As the rainy season brings greenery to the region, the butterflies and their caterpillar offspring feast on a variety of plants until their wintering spots dry up. Then the butterflies fly north to Europe. Â
Pinpointing exactly where painted lady butterflies (Vanessa cardui) overwinter and breed was the last unknown piece of their roughly 15,000-kilometer migration, says Gerard Talavera, an entomologist and evolutionary biologist at the Botanical Institute of Barcelona. The species — one of the most common butterflies in the world — boasts the longest round-trip journey of any butterfly (SN: 6/20/18).
Painted ladies aren’t the only insects to make such long migratory trips, says Constantà Stefanescu, a butterfly ecologist at Museu de Ciències Naturals de Granollers in Spain who was not involved in the study. Understanding how these butterflies do it provides a framework to explore how other migratory insects, including destructive pests, make such treks (SN: 4/8/18).
Scientists knew that the painted ladies went to Africa, but where on the continent they waited out European winters from December to February was a mystery (SN: 10/12/16). The butterflies cross the Sahara and arrive in countries such as Chad in the fall. Around November the insects fly elsewhere, Talavera says, but it was unknown where they landed.
Before this study, Talavera and colleagues had predicted that subtropical regions close to the equator might provide suitable habit. To know for sure, the…
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