Mosquitoes spend a lot of time in the air—it’s how they hunt, find mates, and even lay eggs. But for all the time they’re actually airborne, it turns out they’re not actually that efficient at flying.
In a paper published (paywall) today (March 29) in Nature, a team of researchers led by Richard Bomphrey, a biomechanical engineer at the Royal Veterinary College, London in England, describe how under the scrutiny of eight cameras that took 10,000 frames per second, mosquitoes revealed exactly how they fly.
Unlike similar-sized insects like butterflies or bees, which catch wind with large wing flaps, mosquitoes combine of short wing flaps with a swiveling motion that rapidly moves the wings back and forth, to create pockets of air to launch them into flight and keep them afloat.
Think of sticking your hand outside a car window, Laura Miller, a computational biologist at the University of North Carolina not affiliated with the paper, wrote in an accompanying news article in Nature. When you change the angle of your hand, you can feel the air giving it lift. Mosquitoes move their wings in a way that creates this lift both forwards and backwards. When mosquitos swivel their wings around while flapping them up and down, they’re able to capture the force and get a little higher in the air for it.
The trouble is, this method means that mosquitoes end up beating their wings almost four times faster than other insects their size. That’s because the mosquitoes have a much smaller range of motion in their wings when they fly compared to other insects. Bomphrey and his team found that when mosquitoes move their wings up and down, they only cover about 44 degrees(out of the 360 degrees that would make a full circle_); a butterfly, whose wings touch at the top, has a 180-degree range of motion. As a result, mosquitoes have to flap their wings about 720 times per second, much more than scientists would expect for an insect their size. The power needed for faster wing strokes increases exponentially—a huge energy suck that mosquitoes compensate for by, well, a lot of blood-sucking.
So what evolutionary advantage could mosquitoes possibly gain through their energy-inefficient flying? Perhaps a literal buzz. “It’s very likely to be acoustic communication,” says Bomphrey.
Other insects, like cicadas (paywall) and crickets use the sounds they make to let others nearby know they’re looking for a mate (or not). Although these insects make noise with their legs, it could be that mosquitoes have evolved to be able to communicate through the hum of their wings beating—roughly a high-E string on a violin for females, and males a bit higher, Bomphrey estimates. Understanding these sounds and the messages they convey could improve acoustic traps—no small matter since the species studied, Culex quinquefasciatus, is known to transmit the West Nile virus.
Ultimately, Bomphrey is less interested in mosquito communication or pest control than he is in the variety of ways animals have evolved to travel through the air. “We know everything that flies has to overcome the force of it’s weight,” he says. “We’re really trying to explain the diversity of life on Earth, and how that is constrained by physics.”