Butterflies may look fragile, but some species found across Africa migrate enormous distances, crossing deserts, seas and even oceans.
The painted lady butterfly is one of the most remarkable examples.
These butterflies move between Africa and Europe as part of a huge migration that unfolds across several generations. Researchers have documented painted ladies travelling across the Sahara and Mediterranean during their journeys.
Scientists have even found large concentrations of painted ladies in countries including Chad, Niger and Benin.
Thousands of butterflies can appear together
Painted ladies do not simply remain in one location throughout the year.
Their movements follow changing environmental conditions, including rainfall and the availability of vegetation.
When conditions are particularly favourable, their populations can increase dramatically.
In 2019, unusually large numbers of painted ladies appeared across Africa, the Middle East and Europe. Researchers linked the outbreak to abundant vegetation that provided favourable breeding conditions.
In earlier fieldwork in Chad, Benin and Niger, scientists recorded concentrations reaching as many as 20,000 painted ladies per hectare in some locations.
Their journey can cross the Sahara
The Sahara might seem like an impossible barrier for an insect weighing only a fraction of a gram.
Yet painted ladies regularly undertake trans-Saharan movements.
Their wider migratory cycle between the Afrotropical and Palearctic regions can span around 15,000 kilometres across multiple generations, according to research published in Nature Communications.
No single butterfly necessarily completes that entire migration.
Instead, successive generations continue different stages of the journey.
Some even crossed the Atlantic
One discovery revealed just how far these butterflies can travel.
Researchers investigated painted ladies found on a beach in French Guiana in South America, where the species does not have an established native population.
Evidence from wind patterns, DNA, pollen and chemical signatures indicated that the butterflies had arrived from West Africa.
Scientists concluded that they had travelled at least 4,200 kilometres across the Atlantic, probably taking between five and eight days. Favourable winds were crucial to making the crossing possible.
The butterflies may originally have emerged in Western Europe before travelling through Africa, potentially making their overall journey more than 7,000 kilometres.
Tiny insects, enormous journeys
Painted ladies show that some of the world’s great migrations are happening almost unnoticed above us.
Their movements connect different parts of Africa with Europe and, in exceptional circumstances, even regions across the Atlantic.
Scientists are still studying how weather, vegetation and seasonal changes influence these movements.
For an insect that can fit easily in the palm of a hand, the distances involved are extraordinary.