1. The stretch receptors of the wing hinge of the locust Schistocerca fire once or twice at the top of the wingstroke during normal flight.
2. Removal of the four stretch receptors results in a decrease of the wingstroke frequency to about one-half normal.
3. Interference with the normal timing of the stretch-receptor input (mechanically or by electrical stimulation) does not affect the normal wingstroke frequency. With respect to this sensory source the centrally generated motor output pattern is independent of input phase.
4. The results are discussed briefly in relation to the question of central υ. peripheral control of locomotion.