Lhe world of insects is largely unknown to us. With some 1.3 million species listed by them, and 10,000 new ones described each year, entomologists can rightly say that they are not idle. However, according to the evaluations used, the reality would be 10 or even 100 times greater. As for the biomass of insects, it would be four times greater than that of all vertebrates, 300 times that of humans. Suffice to say that on the subject, the discoveries are not lacking.
Nevertheless: the one that an international team, led from Lomonossov University in Moscow, published in the journal Nature, this January 19, appears quite exceptional. She has in fact just discovered that the smallest insects in the world, beetles of less than half a millimeter united in the group of Ptiliidae, were performing a very unique flight, which the team sums up simply: “They row through the air. » Even more surprising, “this flight allows them to reach an exceptional speed”, says Alexey Polilov, director of the entomology laboratory at Lomonosov University. “If we relate this to the size of their body, they surpass all the animals for which this parameter has been measured”, he says.
The team had already published several articles in recent years detailing the biology, anatomy and performance of Paratuosa cakes a flying bolide less than 0.4 millimeters, the model species of the group. But they had not yet filmed in detail and analyzed the flight of these tiny beetles, the size of an amoeba. Neither modeled their movements and the flow of air around their wings. “This time, we have the whole story, and it is really beautiful”, greets Jérôme Casas, professor of ecology at the University of Tours and specialist in insects.
Wings covered with hair
The first chapter was actually written in the 19th century.e century, when entomologists discovered that certain insects that seemed to come from the world of the Liliputians had the particularity of having wings not covered with a membrane but with hairs. As the decades passed, researchers understood the reason. “Below a millimeter, they move through the air as in a viscous fluid”, summarizes Jérôme Casas. The air thus “sticks” to the hairs. Like the hands of a swimmer not closing his fingers, the comb-shaped wings therefore retain a certain efficiency, while benefiting from a weight much lower than that which a membrane would impose.
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