00:00Why are flies so hard to swat?
00:05A fly buzzes past your head and lands nearby.
00:08You grab a fly swatter and you strike.
00:11But no matter how quick you are, the fly escapes unharmed.
00:15What is it that makes flies so hard to swat?
00:19Flies have many adaptations that give them extra speed, maneuverability
00:24and perception, making them very, very good at
00:27detecting and evading your swats. And new evidence shows
00:31that one of the ways they do that is with vibrations of stick-like
00:35structures with a knob at the end, called halteers. When halteers
00:39vibrate during flight, they're sensing body rotations and
00:43transmitting information to the flies' wings, which helps flies to stabilize their bodies.
00:48However, houseflies also vibrate their halteers
00:52while walking, but scientists didn't know why. So they looked at
00:55houseflies and their close relatives to see if oscillating halteers
00:59affected how the flies launch into the air.
01:02Scientists filmed flies during takeoff using high-speed cameras,
01:06recording footage at speeds up to 3,000 frames per second.
01:10They found that houseflies, and other closely related flies,
01:14launch themselves around five times faster than other flies,
01:18and with just one wingbeat.
01:20When scientists removed those flies' halteers,
01:23it took them longer to take off,
01:25and some took a nosedive and crash-landed.
01:28But halteers
01:29aren't the only secret weapon in a
01:31fly's evasive arsenal.
01:33Fruit flies can change course in under
01:35one one-hundredth of a second,
01:37about 50 times faster than an eye can blink.
01:40Flies also have
01:41exceptional vision, which helps them react
01:43to a threat, and adjust their trajectory
01:46within milliseconds before takeoff.
01:50With all these built-in advantages,
01:52it's no wonder that the fly you're trying
01:54to swat can easily escape
01:56and just buzz off.
02:00Aerodynamic flies.
02:01Just another one of life's little mysteries.
02:04One-hundredth of a thousand years.
02:04Two-hundredth of a thousand years.
02:05Two-hundredth of a thousand years.
02:05Two-hundredth of a thousand years.
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