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Despite their small size, ladybugs are equipped with a unique anatomy that allows them to transition from flight to ground movement with ease.

But the mechanism behind how the insects are able to keep their wings strong and rigid during flight, yet elastic enough for compact folding once on the ground hasn’t been fully understood, until now.

Ladybug wings consist of the hardened elytra, the forewings with the distinct spots, and the soft-membrane hindwings used for flight, which are covered and protected by the elytra. The insects also close the elytra before folding their wings, which has restricted previous attempts at observations.

Therefore, researchers at the University of Tokyo created an artificial, transparent elytra to better understand how the wings remain strong and rigid for flight, but also become elastic for compact folding once on the ground.

As explained in a press release detailing the study, the team created the artificial elytron from ultraviolet light-cured resin, which is commonly used in nail art, using a silicon impression of an actual elytron removed from a Coccinella septempunctata spotted ladybug. The artificial wing case was then transplanted back onto the ladybug to replace the missing forewing.

The findings were published in the Proceedings of the National Academy of Sciences.

High-speed cameras filmed the ladybug’s “deploy and collapse” technique to provide the researchers with the view they were hoping for. CT scans of both folded and unfolded wings were also taken to analyze the 3-D folding pattern.

They found that the curvature of the elytron mimics the shape of the hindwing veins, and ladybugs use the edge and lower surface of the elytron to fold the wings along crease lines, similar to origami. The insect also employs abdominal lifting movements to help get their wings into their “storage space.”

The researchers compared the curved wing veins to that of the measurement tool tape spring, also known as carpenter tape.  Similar to the tape, the veined wings hold firm when extended, but can also bend and be stored in a compact manner.

This unique ability could have significant implications for engineering science, according to the researchers, and could be used to design a wide range of structures – from satellite antennas to microscopic medical instruments, and even everyday consumables like umbrellas.

"The ladybugs' technique for achieving complex folding is quite fascinating and novel, particularly for researchers in the fields of robotics, mechanics, aerospace and mechanical engineering," said Kazuya Saito, assistant professor of the University of Tokyo’s Institute of Industrial Science.

 

Video credit: Kazuya Saito

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