Some butterflies may be able to travel across entire oceans with the help of the wind.
A world-first study has now shown that the painted butterfly (Vanessa cardui) can cross the world’s second largest ocean, the Atlantic, covering 4,200 kilometers (2,610 mi) in just five to eight days.
The researchers say this journey is “among the longest documented for any single insect species and is potentially the first verified transatlantic crossing”.
The incredible discovery was made after more than ten years of mystery.
It all started in 2013, when a flock of weary butterflies landed on the beaches of French Guiana with tattered and tattered wings. Entomologist Gerard Talavera, who found the insect resting on the sand one morning in October, was shocked.
They were painted butterflies – a common species with stable populations found on every continent except Antarctica and South America.
For years, Talavera wondered: how did insects get to South America and where did they come from? He finally has an answer.
By analyzing the DNA of the pollen left on the butterflies, Talavera and his colleagues at the Botanical Institute of Barcelona showed that this lost flock likely arrived from sub-Saharan Africa after making a fortuitous transatlantic journey.
The adult insect appears to have been caught in a strong trade wind in 2013 and blown 4,200 kilometers off course.
Judging by the trade winds that year, the journey would take the butterflies about five to eight days. If there was nowhere to land, insects would have to use their wings sparingly.
Scientists believe that without the help of strong winds, the flock would only travel about 780 kilometers before using up all their energy and perishing.
“Our findings suggest that we may be underestimating the transoceanic dispersal of insects and overemphasizing the importance of trade wind trade fairway air highways,” write Talavera and colleagues.
Monarch butterfly (Danaus plexippus) is world famous for its nearly 5,000-kilometer annual migration from North America to Mexico, but painted butterfly butterflies also make long-distance journeys between Europe and Africa each year. Some studies suggest that one generation can migrate more than 4,000 kilometers.
This would make it the butterfly with the longest lifetime migration, but unlike other animals that travel through the air, such as birds, it is much harder to track the global movements of small creatures such as insects.
The wings of painted butterflies in French Guiana have been found to contain isotopes that indicate they were born in Western Europe. This means that the flock could have traveled more than 7,000 kilometers in one lifetime and visited no less than three continents.
“This is the first time that this combination of molecular techniques including isotopic geolocation and pollen metabarcoding has been tested on a migratory insect,” says geochemist Clément Bataille of the University of Ottawa in Canada.
“The results are very promising and transferable to many other migratory insect species. This technique should fundamentally change our understanding of insect migration.”
While the long-distance migration from Europe to Africa or North America to Central America is undoubtedly impressive, there are also plenty of places for butterflies to stop and refuel. Crossing the ocean is a completely different challenge.
Painted ladies may only have wings the size of little fingers and brains the size of a pinhead, but they are incredible flyers.
In fact, their small size gives them an advantage. It allows the species to glide along the wind, sometimes at speeds of up to 48 kilometers (30 miles) per hour.
Scientists also underestimate not only these inferior insects.
Winds that blow across the Atlantic from the Sahara to the tropical Caribbean are also stronger than experts once thought, capable of carrying large dust particles up to 3,500 kilometers away.
It makes sense that a small winged creature could glide quite far in these winds with minimal effort.
“We usually see butterflies as symbols of the fragility of beauty, but science shows us that they can perform incredible stunts,” says entomologist Roger Vila of CSIC-Pompeu Fabra University in Spain.
“There is still much to discover about their abilities.
The study was published in The nature of communication.