The pissing fly, faster than its shadow

There is an insect that eliminates up to 300 times its body weight in urine. And who, however, manages the feat of not wasting energy.

Indeed, if it went to the toilet like us – or like a dog – this insect would probably have died of exhaustion, considering the number of times it would have to squat or raise its leg – in addition to the muscle movements required. to evacuate urine.

You should know that this insect, which is only a few millimeters long, feeds by sucking the leaves, or more exactly the liquid that circulates in the xylem, or the network of “tubes” that connects the roots to the leaves. But since this liquid is 95% water, to extract the necessary minimum of nutrients from it, the insect must absorb a huge amount. And since that means he has to urinate a lot, he has long been known to expel his urine in a high-velocity jet of droplets, earning him the sympathetic name “mouche pisseuse” in French.

However, this method must be energy efficient, otherwise the insect would not survive. Researchers at the Georgia Institute of Technology in Atlanta therefore wanted to understand the “= technique”. Using miniature cameras, they followed the movements of five of these Homalodisca vitripennis – their official Latin name -, and in particular of a pointed appendage, called an “anal stylet”: by a movement of rotation and pressure on the droplets before they emerge, they are “catapulted” at a speed of 30 centimeters per second. As 80 thousandths of a second elapse between each drop, the phenomenon takes the form of an ultra-fast jet – and less energy-intensive.

The phenomenon does not only interest biologists. In fact, the lead author of the research, which appeared in Nature Communications, is an engineer: the discovery of this “super-propulsion” could inspire the design of self-cleaning machines, de-icing systems, or even transportation systems.

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