Butterflies make record-setting journey across the Atlantic

Painted lady butterflies have fluttered thousands of miles across the Atlantic on a record-setting journey to South America. Researchers say the butterflies flew at least 2,600 miles—and maybe more than 4,300 miles—on a journey that carried them across the ocean from West Africa or Europe. That’s farther than any insect is known to have flown.

“We tend to see butterflies as a symbol of the fragility of beauty, but science shows us that they can perform incredible feats,” said Roger Vila, a researcher at the Institute of Evolutionary Biology in Barcelona and a co-author on a study published in Nature Communications documenting the historic flight.

The findings stem from an unusual discovery. In 2013, Gerald Talavera, a Spanish National Research Council researcher at the Botanical Institute of Barcelona, noticed several painted lady butterflies (Vanessa cardui) along the Atlantic coast of French Guiana. That was strange, since the species isn’t known to occur anywhere in South America.

The butterfly does live in North America, but after analyzing wind patterns, the researchers landed on another possibility. What if the butterflies rode the currents west from Africa or beyond?

Some genetic sleuthing supported their theory. The butterflies’ genetics matched species that live across the Atlantic. DNA from pollen on their bodies came from two plants found only in tropical Africa. That would indicate the butterflies journeyed at least from West Africa, some 2,600 miles away.

But maybe the trip began even farther away. A chemical analysis of their wings—which preserve stable isotopes from their place of origin—determined that their trek likely originated in western Europe. That could mean a flight of over 4,300 miles, possibly starting in France, Ireland, the United Kingdom or Portugal before reaching Africa and heading west.

“This is an extraordinary feat for such a small insect,” said co-author Clément Bataille, a professor at the University of Ottawa in Canada.

The researchers calculated the butterflies rode favorable wind currents for a nonstop journey of five to eight days. And they may not be alone. The same currents that blow Saharan dust to the Americas may transport living organisms, the researchers found. And with climate change altering global weather patterns, such long-distance dispersals may be on the rise.

“This discovery opens new perspectives on the capabilities of insects to disperse over long distances, even across seas and oceans,” Talavera said.