The painted lady butterfly makes the longest known migration of any butterfly to date, according to new research from the British Ecological Society.
Each year, painted lady butterflies travel over 7,450 miles and cross the Sahara Desert twice in the process as they migrate from Europe to Africa and then to the Mediterranean in early spring.
The Palearctic-African migratory circuit is unprecedented for butterflies, and because insect movement is difficult to track, researchers were unsure exactly how painted lady butterfly offspring made the journey.
“It is difficult to study the movement of insects by means of observations, marking, or radio tracking, since there are millions of individuals and they are very small,” said Gerard Talavera, leader of the research.
In order to better understand the full scope of painted lady butterfly migration, Talavera and a team of researchers first had to discover where the butterflies first developed as caterpillars.
The researchers pinpointed the natal origin of the butterflies by analyzing stable hydrogen isotopes from the wings of adult painted lady butterflies.
Stable hydrogen isotopes are geographic specific and can help researchers locate where the butterflies transformed from caterpillars to butterflies.
The researchers discovered that the butterflies seemed to stay in the Afrotropics over the winter and their offspring made the migration to the Mediterranean, starting the cycle all over again.
Painted lady butterflies travel over 12,000 kilometers every year between generations.