Study solves mystery to how butterflies fly

Butterfly flight has long been a mystery to scientists. Credit: PA

Scientists believe they have found the secret to how butterflies fly.

Until now, the flight of butterflies had remained somewhat a mystery.

The insects, with their unusually short, broad and large wings relative to their body size, have long had scientists scratching their heads as to how they can get airborne.

But a new study has found that the butterfly takes off by generating thrust by the way their wings cup and 'clap' as they bring them together.

Swedish scientists have built on 50 year old research that suggested butterflies' upstroke wing clap helped produce enough force to allow them to fly.

To test these hypotheses, scientists at Lund University constructed a mechanical clapper with two sets of wings, one rigid and one flexible.

They found the upstroke clap thrusts the butterflies forward while the downstroke helps to balance their bodies.

Take off in the wild. This butterfly is performing a routine voluntary take-off flight and demonstrates the upstroke clap. 

In a paper, published in the Royal Society Journal, the researchers behind the study said: "Our findings when studying the butterflies indicated an important role of wing flexibility for the performance of wing claps.

"During the wing clap, the wings of the butterflies were not just two flat surfaces slamming together. At the instance of the clap, when the two wings meet, the wings had a reversed camber, likely owing to their flexibility."

They continued: "We further show that flexible wings dramatically increase the useful impulse (+22%) and efficiency (+28%) of the clap compared to rigid wings.

"Combined, our results suggest butterflies evolved a highly effective clap, which provides a mechanistic hypothesis for their unique wing morphology."