Passage V

Riders on the Storm

[1]

[1] But exactly how these tiny creatures avoid being knocked out of the air during storms were puzzling to entomologists for years. [2] While a typical mosquito measures about three millimeters in length, a raindrop is usually between two and eight millimeters in diameter. [3] More important, a single raindrop can weigh up to fifty times more than the average mosquito. [4] A mosquito might be hit by a drop this size over and over while flying through a moderate rainstorm. [5] Mosquitoes don't dodge raindrops.(63)

[2]

To study how mosquitoes contend with raindrops, mechanical engineer and biologist Dr. David Hu placed mosquitoes inside a clear acrylic box with mesh over the top. [A] He then sprayed water through the mesh at varying intensities to simulate rainstorms and used high-speed videography to film the mosquitoes in action. [B]

[3]

When struck in the legs (the most common point of impact), a mosquito simply rolls sideways and then resumes regular flight. But when struck squarely on the body, the insect joins the droplet, suddenly riding along as the droplet hurtles downward for up to twenty mosquito body lengths. Then the mosquito, which appears to use its long legs and wings to twist free from the droplet and smoothly glide off and away from the droplet. This midair moment of separation occurs so quickly that—the mechanics remain unclear. The entire interaction, therefore, lasts only a fraction of a second. [C]

[4]

Despite the uncertainties, it is clear that the features that would seem to put the mosquito at risk in storms—its size and low weight in comparison with the drops—are precisely what allow it to effectively elude the force of an impact by riding a raindrop. This investigation has yielded information that, perhaps surprisingly, could benefit humans. [D] Mosquitoes have relinquished a new model for the development of tiny airborne robots that can be used for search-and-rescue operations as well as for surveillance. With these robots, as with mosquitoes, rainstorms play a significant role in nature.