Scientists have long been baffled about how the butterfly moves through the air as it does.
Butterflies have long been believed to “clap” their large wings to move forward, but Swedish scientists have determined that the movement is much more complex than previously understood.
Instead of hitting them, they flex the colored wings to create a “pocket” that traps more air and provides more propulsion.
This additional increase in takeoff speed can help majestic lepidopterans avoid predators.
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Scientists in Sweden analyzed the slow-motion video of a silver-washed fryer in flight and determined that the butterfly not only flutters its wings. It forms a “pocket” when attached, aiding propulsion
Butterflies are a tasty food for a variety of animals, such as frogs, spiders, lizards and birds.
“If you’re a butterfly that is able to take off faster than others, that gives you an obvious advantage,” Per Henningsson, a biologist at Lund University, told the BBC.
“Then it’s a strong selective pressure, because it’s a matter of life or death,” he added.
In an analysis published in the journal Interface, Henningsson and his biologist Cristoffer Johansson showed that the “clap” of a butterfly generates a jet of air propulsion.
Researchers believe the added push to take off may help butterflies avoid predators such as frogs and birds.
They also found that he performs this move “in a much more advanced way than we ever realized,” Henningsson told AFP.
For now, the wings fluttered together, “they weren’t just two flat surfaces colliding together.”
Instead, they form a “pocket” shape that traps more air.
Henningsson said it was unclear whether butterflies use the pocket technique during free flight, “but in the takeoff phase, they definitely do a lot.”
After watching a slow-motion video of the common silver-washed fryer in flight, Henningsson and Johansson formed two pairs of simple mechanical wings.
One set was stiff, the other flexible, like real butterfly wings.
Mechanical wings that were as flexible as butterflies were 28 percent more efficient and 22 percent better at generating strength than rigid wings.
The researchers found that flexible wings were 28% more energy efficient (a “spectacular improvement”) and 22% better at generating strength.
“While conventionally considered aerodynamically inefficient,” butterfly wings could be ideal for forming pocket shape, Henningsson said.
Their findings could be useful in creating drones that use the propulsion of the wings applauding, he added.
Last year, Cosmos reported that engineers at the University of South Australia introduced a bird-sized “ornithopter,” a flying machine that flutters its wings to generate forward thrust.
“People working on these designs … should look at this behavior in the form of a cup, since there are [is] a lot of efficiency and effectiveness can be achieved, “Henningsson told the BBC.
The report could also help highlight the importance of research into these beautiful insects, whose numbers are in sharp decline.
A new report by Butterflies Conservation Europe found that the butterfly population in the UK has halved since 1976, with almost one in ten species of British butterflies being extinct due to the destruction of the habitat.
In California, the number of Western monarch butterflies has plummeted to less than 2,000 butterflies out of the tens of thousands counted in recent years and millions reported in the 1980s.
Sarina Jepsen of the Xerces Society, which conducts the annual count of California monarchs, told the AP that “their absence this year was heartbreaking.”