Stridulation is the production of sounds by rubbing two parts of the body together; this mechanism is best known in crickets, grasshoppers, and cicadas. Larval Lucanidae, Passalidae[?], and Geotrupidae[?] also stridulate, rubbing a series of ridges on the coxa of the middle legs with a scraper on the trochanter of the hind leg.
... simple. It can easily be understood with a little knowledge of gyroscopes. Their striking property is that the axis of a spinning gyroscope will resist a force ...