How Mosquitoes Sneak Away After Feasting on Your Blood
Special wingbeats and long legs help mosquitoes take off without getting smushed
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Imagine tucking into a truly epic Thanksgiving feast—one that doubles or triples your bodyweight—then trying to silently slink out of the dining room without anyone noticing. Chances are you’d be slow, lethargic and your belly would knock over Grandma’s collection of Hummel figurines. But mosquitoes seem to pull off a similar feat, filling up with human blood and then evading detection as they fly away.
How do they do it? To figure out the answer, as Kendra Pierre-Louis reports for Popular Science, researchers used high-speed cameras, capable of shooting 125,000 frames per second, and teased out the steps of this incredible feat.
Recording the motions of these tricky subjects was no easy feat, explains University of California, Berkeley graduate student Sofia Chang, who wrangled mosquitos and even fed some of them with her own blood. It took the filming of 600 individual Anopheles coluzzii mosquitoes to get the setup just right.
But eventually the researchers captured videos of the take-off sequence, showing the mosquitoes in silhouette as they finished their meals and then departed. The team analyzed 32 videos of blood-filled mosquitoes and 31 unfed mosquitoes, creating 3D renderings of the wing beats to figure out the lift and aerodynamic forces. The research appears in The Journal of Experimental Biology.
It turns out, the mosquito’s takeoff strategy is the opposite of most other flyers including birds and other insects. A housefly, for example, uses its legs to leap into the air before flapping its wings, a relatively bumbling operation that is efficient, but draws a little attention. The mosquitoes, on the other hand, rev up their wings to 600 flaps per second, about three times as fast as most other insects, buzzing about 30 milliseconds before lifting up into the air.
The mosquito also changes its angle so it can sweep its wing across a longer distance creating more lift than normal. This creates about 60 percent of the force needed to get airborne before it pushes off. “The other thing is they have these very long legs they can extend,” Florian Muijres, researcher at Wageningen University in the Netherlands and an author of the study, tells Pierre-Louis. “They can distribute the forces that they need to distribute to the leg over a longer period of time.”
This all leads to a liftoff so gentle it produces almost no force on the host’s skin, preventing the insect from tripping any nerves and evading detection, which prevents it from getting smooshed. “Instead of going fast, they take their time, but they accelerate the entire time so that they reach a final velocity pretty much the same as fruit flies,” Chang says in the press release. “That is something that might be unique to mosquitoes, and maybe even unique to blood feeders.”
The research isn’t just about understanding our least-favorite blood sucker. Figuring out how the insect comes and goes undetected could have implications for building tiny bug-sized robots. In 2015, researchers also looked at how those long legs help reduce adhesion force, allowing mosquitoes to walk on water to lay their eggs, which may also help in robotics. So far, there aren’t any mosquito-sized drones or robobugs out there, that we know of, but researchers are getting close. Several teams are working on artificial bees, which one day may help pollinate crops and could even help in search and rescue missions.