HOW do flies right themselves so swiftly after being batted away in mid-flight? Experiments on fruit flies suggest their stabilisation systems are similar to the gyroscopes of early aeroplanes.
Flies are known to reorient themselves from small disturbances faster than their visual systems can react. In lieu of hind wings, they have two tiny sensors, called halteres, that measure changes in direction. It is thought that the halteres are wired directly to the wing-control system, allowing them to recover quickly.
To determine how halteres work, of Cornell University in Ithaca, New York, placed tiny magnetic rods on the backs of fruit flies and released them. Altering the magnetic field around the flies made the rods twist, pushing the flies off course (Proceedings of the National Academy of Sciences, ).
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Simultaneous recordings by three high-speed cameras showed that the flies can right their course to an accuracy of 2 degrees within 60 milliseconds. Drag on their wings dampens their rotation, then the flies 鈥渞ow鈥� their wings to right themselves. This is akin to early planes, which used gyroscopes to automatically adjust wing shapes to help stabilisation in flight.