Buzz off: Flies have traditionally been difficult to swat, but preempting their crafty behaviour could help to strike them more effectively.
Credit: iStockphoto
SYDNEY: Using high-speed video footage, bioengineers have discovered the key to the evasive manoeuvrability of flies – and found the best strategy for swatting them successfully.
Michael Dickinson has been interviewed hundreds of times about his research on the biomechanics of insect flight. One question has always dogged him: Why are flies so hard to swat?
"Now I can finally answer," said Dickinson, a bioengineer at the California Institute of Technology in Pasadena, USA.
Tiny brain, big escape plan
Using high-speed, digital imaging of fruit flies (Drosophila melanogaster) faced with a looming swatter, Dickinson and graduate student Gwyneth Card determined the secret to a fly's crafty behaviour.
Long before the fly leaps, its tiny 'brain' calculates the location of the impending threat, comes up with an escape plan, and places its legs in an optimal position to hop out of the way in the opposite direction. All of this action takes place within about 100 milliseconds after the fly first spots the swatter.
"This illustrates how rapidly the fly's brain can process sensory information into an appropriate motor response," said Dickinson who this week publishes a paper detailing the research in the U.S. journal Current Biology.
In this study, the swatter was actually a 14-centimetre-diameter black disk, dropping at a 50º angle toward a fly standing at the centre of a small platform.
The researcher's videos show that if the descending swatter comes from in front of the fly, the fly moves its middle legs forward and leans back, then raises and extends its legs to push off backward.
Rear attack
When the threat comes from behind, however, the fly (which has a nearly 360º field of view) moves its middle legs a tiny bit backwards. With a threat from the side, the fly keeps its middle legs stationary, but leans its whole body in the opposite direction before it jumps.
"We also found that when the fly makes planning movements prior to take-off, it takes into account its body position at the time it first sees the threat," Dickinson said.
"When it first notices an approaching threat, a fly's body might be in any sort of posture depending on what it was doing at the time, like grooming, feeding, walking, or courting," he said.
How to swat a fly??
Exactly how much money was spent to discover the life-changing revelation that swatting at where a fly is going to be is more effective than swatting at where it was?
Please tell me that some other more substantial knowledge was gained by this. Please tell me this money wasn't spent just to learn how to swat a fly.
RE: How to swat a fly??
I reckon that this 'attack strategy' was the headline grabber thought up after the event rather than the reason for the research itself. Understanding the intricacies of insect nervous systems has huge potential benefits. Experiments on the visual guidance system of bees for example have informed the development of computer vision methods that will probably eventuate in things like automated transport systems one day soon.
And with summer on the way, its good to have a better idea of how to nail those little suckers too!
Big Bucks Revelation
I agree. I thought the same when I read this article. My husband worked this out years ago. He catches a fly at every attempt!!! Hee Hee!
Very easy to swat a fly if you can move the object it rests on.
I get them every time if I move the object the fly is resting on against another object (hand, surface etc.) Try it and you will be surprised. For some reason the fly does not sense the motion of the object it is resting on.