Science

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The Science of Fly Swatting

March 24, 2009 02:17 PM
by Denis Cummings
A California scientist has studied how flies avoid being swatted, finding that they are able to react to potential danger in less than a 10th of a second.

‘Anticipate Where the Fly Is Going to Jump’

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Michael Dickinson of the California Institute of Technology in Pasadena has studied flies his entire career, focusing on how they fly. His latest project has a much more practical purpose for anybody who has ever been annoyed by a fly: how they evade swatting.

In a study published in the August issue of Current Biology, Dickinson used high-speed, high-resolution cameras to film how flies react to seeing a swatter approaching it. He found that within 50–100 milliseconds of seeing the swatter, a fly begins to prepare its getaway by adjusting the position of its legs and body.

“Our experiments showed that the fly somehow ‘knows’ whether it needs to make large or small postural changes to reach the correct pre-flight posture,” said Dickinson. “This means that the fly must integrate visual information from its eyes, which tell it where the threat is approaching from, with mechanosensory information from its legs, which tells it how to move to reach the proper pre-flight pose.”

The fly’s quick reaction beats that of humans, who need at least 250 milliseconds to react to stimulus. The fly, meanwhile, can perceive the threat, determine where the threat is coming from, and adjust its body in less than half the time. “We really see a marvelous machine, arguably the most sophisticated flying device on the planet, and its all controlled by this brain about the size of a poppy seed,” Dickinson told NPR.

Dickinson says that he plans to focus his future research on the fly’s brain, searching for where in the brain the sensory-to-motor transformation occurs. He compares the brain to a “minicomputer the military would like to build into tiny robot spy planes that fly into hostile territory.”

Dickinson says the key to successfully swatting a fly is to outthink it. “It is best not to swat the fly’s starting position, but rather to aim a bit forward of that to anticipate where the fly is going to jump when it first sees your swatter,” he says.

Background: The Dickinson Lab

Dickinson created the Dickinson Lab to study flies along with his graduate student, Gwyneth Card. The lab features a system of high-speed cameras shooting at 6,000 frames per second to study the motion of flies.

Dickinson has created flight simulators for flies using two small arenas lined with computer-controlled LEDs. The Free Flight Arena (also called Fly-O-Rama) simulates flight from the fly’s view, while the Mechanical Flight Simulator (aka Rock-n-Roll Arena) examines the output of the fly’s flight. He has also created two mechanical flies, known as Robofly and Bride of Robofly, for the study of aerodynamics of flapping and forward flight.

Video: Fly escape

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