Why don't mosquitoes get squashed by raindrops? Scientists find an answer.
A mosquito getting hit by a raindrop is equivalent to a human getting hit by a car, but the insects have evolved a way to roll with it.
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To understand how the mosquitoes survived, Hu and his colleagues suspended Styrofoam pellets of various weights under water droplets, and found that mosquitoes' low mass explains their ability to survive. If a mosquito sitting on a twig gets hit by a droplet, the water will crush the insect with 10,000 times its body weight in force. But if a mosquito is hit in midair, only 10 percent of the droplet's force transfers to the insect's body. That's only about 0.02 ounces (0.6 grams) for a typical droplet, the equivalent of a mosquito being hit by a feather.Skip to next paragraph
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In contrast, a dragonfly that weighs more than 1,000 times that of a mosquito would absorb 90 percent of a droplet's force. The heftier dragonfly would stop the droplet rather than surfing it down like the lightweight mosquito.
"There's something special about being very lightweight," Hu said.
If mosquitoes fly too close to the ground, they do risk death by droplet, the researchers found. The insects need to leave themselves five to 20 body lengths to detach from the raindrops, or they'll hit the ground at a speed of 1,000 mosquito body-lengths per second.
In their natural environment, mosquitoes probably seek shelter from rain, Hu said. But they need to be able to survive the first droplets during that mad dash. Hu and his colleagues now plan to investigate how mosquitoes deal with other inclement weather conditions, such as dew.
"It's well known that these insects are robust. They basically can survive any kind of wind and most weather conditions," Hu said. "We want to understand what body adaptations do they have to survive these kinds of things and how can that be used for engineering?"
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