Private ultrasonic whispering in moths.

Sound-producing moths have evolved a range of mechanisms to emit loud conspicuous ultrasounds directed toward mates, competitors and predators. We recently discovered a novel mechanism of sound production, i.e., stridulation of specialized scales on the wing and thorax, in the Asian corn borer moth, Ostrinia furnacalis, the male of which produces ultrasonic courtship songs in close proximity to a female (<2 cm). The signal is very quiet, being exclusively adapted for private communication. A quiet signal is advantageous in that it prevents eavesdropping by competitors and/or predators. We argue that communication via quiet ultrasound, which has not been reported previously, is probably common in moths and other insects.