Scientists have long been puzzled about exactly how butterflies move through the air as they do.
It has long been thought that butterflies “clap” their large wings to push forward, but Swedish scientists have now established that the movement is much more complex than previously understood.
Rather than flapping them, it flexes its colorful wings to create a “pocket” that captures more air and provides more propulsion.
This additional increase in take-off speed can help majestic lepidoptera avoid predators.
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Scientists in Sweden analyzed the slow-motion film of a silver-washed fryer in flight and determined that the butterfly did not just flutter its wings. They form a “pocket” when they come together, helping to propel
Butterflies are a tasty meal for a variety of animals, including frogs, spiders, lizards and birds.
“If you are a butterfly capable of taking off faster than others, that gives you an obvious advantage,” Per Henningsson, a biologist at Lund University, told the BBC.
“Then there is a strong selective pressure, because it is a matter of life and death,” he added.
In an analysis published in the journal Interface, Henningsson and fellow biologist Cristoffer Johansson showed that the “palm” of a butterfly generates a jet of air propulsion.
Researchers believe that extra take-off force can help butterflies avoid predators such as frogs and birds
They also found that he was performing the move “in a much more advanced way than we have ever done,” Henningsson told AFP.
When the wings fluttered together, “it wasn’t just two flat surfaces colliding.”
Instead, it forms a “pocket” shape that catches more air.
Henningsson said it is unclear whether butterflies use the pocket technique during free flight, “but in the take-off phase, they certainly do a lot.”
After watching the slow-moving video of the common silver-washed fryer in flight, Henningsson and Johansson created two pairs of simple mechanical wings.
One set was stiff, the other flexible like real butterfly wings.
Mechanical wings that were flexible like a butterfly were 28 percent more efficient and 22 percent better at generating force than rigid wings.
The researchers found that flexible wings were 28% more energy efficient – a “dramatic improvement” – and 22% better at power generation.
“Although conventionally considered aerodynamically inefficient,” butterfly wings could be ideally suited to form the shape of a pocket, Henningsson said.
Their findings could be useful in creating drones that use the propulsion of palm wings, he added.
Last year, Cosmos reported that engineers at the University of South Australia unveiled a bird-sized “ornithopter”, a flying car that flutters its wings to push forward.
“People working on these models … should analyze this cup-shaped behavior since then [is] a lot of efficiency and effectiveness to be gained from this, ”Henningsson told the BBC.
The report could also highlight the importance of researching these beautiful bugs, whose numbers are in serious decline.
A new Butterflies Conservation Europe report found that the butterfly population in the UK has halved since 1976, with almost one in ten British butterfly species extinct due to habitat destruction.
In California, the number of Western monarch butterflies has plummeted to less than 2,000 butterflies out of the tens of thousands recorded in recent years and millions reported in the 1980s.
Sarina Jepsen of the Xerces Society, which conducts an annual number of California monarchs, told the AP that “their absence this year has been heartbreaking.”