The fruit fly treadmill, constructed from simple components like belts, pulleys, and motors, measured over four times the length of an average fruit fly. The researchers observed that the flies’ movements on the treadmill mirrored their natural behavior, with the flies surging forward, sprinting to the front of the treadmill, and then standing still as they were carried back to the end. The flies could reach speeds of 50 millimeters, or almost two inches, per second, the fastest ground speed ever recorded for Drosophila.
The study also revealed that the flies’ middle legs played a crucial role in maintaining their balance and direction, adjusting their step lengths to keep the fly moving straight ahead. This middle-leg adaptation was reminiscent of how a fly might respond to a sudden gust of wind, adjusting its strides to counteract the force.