How Fruit Flies Use Cruise Control in Turbulent Wind Conditions

Fruit flies can zip around a room, zooming past obstacles as they slow down and speed up. Now, though, researchers have uncovered the mechanism for how fruit flies use their "cruise control" in flight; it turns out that they don't only use vision, but also use wind-sensing information from their antennae.

In order to find out a little bit more about a fruit fly's flight, the researchers decided to test the limits of the insect's capabilities. A previous experiment simulated natural wind for flies in a wind tunnel, yet it only examined gentle, steady winds. In this particular study, the scientists delivered powerful blasts of air from an air piston within a wind tunnel. This allowed the researchers to see exactly how the fruit flies reacted under extreme conditions when the wind rapidly changed.

While the scientists blasted the insects with wind, they used a set of five digital video cameras that recorded the fly's position from five different perspectives. Then computers combined information from the cameras and determined the fly's trajectory and acceleration.

So what did they find? It turns out that fruit flies accelerate when the wind pushes them from behind and then decelerate when flying into a headwind. In both cases, the flies recovered to eventually maintain their original ground speed. After further testing, the scientists found out that the fruit flies were using their antennae to maintain their speed.

"We know that vision is important for flying insects, and we know that flies have one of the fastest visual systems on the planet," said Michael Dickinson, one of the researchers, in a news release. "But this response showed us that as fast as their vision is, if they're flying too fast or the wind is blowing them around too quickly, their visual system reaches its limit and the world starts getting blurry." At that point, the antennae kick in.

The findings reveal how the wind sensing capabilities of fruit flies actually work. This, in turn, could eventually help scientists create small, flying robots, basing them off of biological fruit flies.

The findings are published in the journal Proceedings of the National Academy of Sciences.