Each Year Painted Lady Butterflies Cross the Sahara — and Then Go Back Again
Published:29 Jun.2018    Source:Science News

 Move over, monarchs. The painted lady butterfly (Vanessa cardui) now boasts the farthest known butterfly migration.

Though found across the world, the orange-and-brown beauties that live in Southern Europe migrate into Africa each fall, crossing the Sahara on their journey (SN Online: 10/12/16). But what happened after was a mystery because the butterflies disappeared. Researchers hypothesized that the insects either remained in Africa or made a round-trip, but there was no evidence either way.

A new chemical analysis of butterfly wings suggests that the butterflies head back to Europe in the spring. The round-trip, which usually plays out over several generations, is an annual journey of 12,000 kilometers, about 2,000 more than successive generations of monarchs are known to travel in a year (SN: 4/14/18, p. 22).