The structures were described in 2013 by Malcolm Burrows and Gregory Sutton, working with high-speed video and scanning electron microscopy. Each hind trochanter carries an arc of ten to twelve teeth that engages the arc on the opposite leg. When the nymph jumps, the gears synchronise leg extension to within about thirty microseconds.
The reason for the mechanism is stability. A planthopper jumping with legs that extend even fractionally out of step would spin instead of travelling; nervous control alone is too slow to correct at these timescales, so the coupling is mechanical.
The gears are lost at the final moult. Adults synchronise their legs by friction between the leg bases instead, which is less precise but does not have the drawback of the nymph system: a broken tooth cannot be repaired between moults, and an adult does not moult again. The gears are the first functioning mechanical gears found in an animal.