"One reasonably well-understood example of a percussive mechanism involving two-body parts is found in members of the Austrlian moth genus, Hecatesi (Bailey, 1978). In these moths an area of the costae of the fore wings is modified to form small hard knobs whichhave been called castanets. These are repeatedly struck together at the top of the wing stroke to produce sounds which have given these insects the popualr name of 'whsitling moths'." 
- . Arthropod Bioacoustics: Neurobiology and Behaviour. Ithaca, New York: Comstock; 1989.