AILSA CHANG, HOST:

If you've ever been frustrated by a housefly evading your swatter, science has a new explanation.

MARY LOUISE KELLY, HOST:

The secret seems to be a part of the fly called the halteres - evolutionary remnants of wings.

JESSICA FOX: They don't generate lift. They're just sensory organs.

KELLY: Jessica Fox of Case Western Reserve University says the halteres allow the fly to stabilize in the air, sort of like how our inner ears tell us where we are in space.

CHANG: Fox's students had noticed that some flies moved these sensory organs a lot, even when just walking around.

FOX: We hypothesized that maybe these flies were using their halteres to help them take off.

CHANG: And thus, an experiment was born. But first, they had to round up some volunteers.

FOX: Your standard trash can, roadkill flies.

KELLY: They filmed those flies with high-speed video cameras as they took off.

FOX: We measured things about their body, like how fast they were taking off, how much they were extending their legs while they were taking off. What we found was that the flies that moved their halteres while they walk - when we removed their halteres, their takeoffs got slower.

KELLY: Suggesting that the halteres were essential for a speedy takeoff, perhaps because they prime a flies' nervous system to jump into flight. The findings were published this week by the Royal Society.

CHANG: Of course, flies do have other advantages, like vision. For a long time, scientists have known that, for flies, we humans seem to move at glacial speeds, making us easy to dodge. Put the two advantages together, and you've got a wickedly fast fly.

KELLY: Yeah. Well, luckily, we humans are smart enough to copy their tricks. Erica McAlister of the Natural History Museum in London says engineers are already borrowing from flies.

ERICA MCALISTER: You can get these kind of boingy, flyey (ph) robotic systems - micro-bots and robotic - miniature robotic systems.

KELLY: McAlister says she's obsessed with flies and appreciates what they can teach us.

MCALISTER: The more we look at flies, the more we can understand and learn the mechanics associated with it, which is why you just got to love a fly.

CHANG: And, she adds, never swat a fly. She would prefer we catch and study them instead.

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