School of Life Sciences

How maggots leap without legs

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Scientists have discovered the astonishing escape method used by tiny maggots without any legs – despite their lack of limbs, they are able to curl their bodies into an improvised spring and launch themselves into the air.

Work by scientists at the University of Lincoln, UK, and colleagues in the US, reveals that this intelligent method of escape is 28 times more efficient than crawling over the same distance.

The new scientific study, led by Dr Mike Wise at Roanoke College and Professor Sheila Patek at Duke University in America, together with Professor Gregory Sutton from the University of Lincoln, is published in the Journal of Experimental Biology. It sheds new light on the fascinating methods used by insects to move large distances with maximum efficiency.

The scientists studied the legless gall midge larvae (also known as maggots). Curling its body into a loop, they observed how each maggot can press down on the rear portion of its body, forming an improvised limb that presses on the ground to propel the creature into the air.

Dr Wise explains why the maggots have developed this unusual technique:“If their galls are damaged in nature, they need to scoot to have a chance at survival. But these Asphondylia maggots don’t simply wriggle away: they catapult themselves to safety, which is quite a feat for an animal with no legs. It borders on the fantastical.”

The team from Professor Patek’s lab at Duke University spent three years examining the larvae and developing a suitable technique to capture the feat of locomotion. The 3mm long Asphondylia maggots only perform their power leaps for a brief period each August; so the team filmed non-stop for the few days they were available in order to capture the take-offs. The leaps can range from 49 to 121mm – up to 40 times the length of the larvae themselves.

Dr Gregory Sutton, Royal Society Research Fellow at the University of Lincoln, then calculated the amount of energy that the insects use to leap instead of crawling. He said: “Crawling is a massive 28.75 times more costly in terms of energy used. For this reason, leaping out of danger really is a no brainer for gall midge maggots.

“The method they use involves planting one end of their body on the ground and sliding the opposite portion of the body until both ends meet. Next the upper portion of the maggot compresses the lower portion until a kink forms midway along the body, producing an improvised leg, which swells as the maggot continues pushing. Then, as the temporary leg gives a final push on the ground, the front end of the body detaches to propel the maggot into the air.”

On closer inspection, the researchers also discovered that the maggots are covered in microscopic hairs. The team suspects that the hairs are so minute that they are able to squash up close enough to an opposing surface to latch on with molecular forces, attaching the two ends of the looped maggot together while it applies pressure to the ground in preparation for take-off.

The paper, titled Adhesive latching and legless leaping in small, worm-like insect larvae is published in the Journal of Experimental Biology.

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