ACOUSTICAL COMMUNICATION AND THE MATING SYSTEM OF THE AUSTRALIAN WHISTLING MOTH HECATESIA EXULTANS (NOCTUIDAE, AGARISTINAE)

Males of the Australian whistling moth Hecatesia exultans produce ultr asonic acoustical signals while perched on low vegetation. Some males call more or less continuously for several hours during midday with in dividuals occupying the same general calling area for up to several we eks. The nearest neighbour of calling males is typically 15 to 25 m di stant, at the outer edge of the estimated range at which neighbours ca n detect each other's ultrasonic signals. Calling male intruders occas ionally enter an occupied territory, resulting in aerial clashes with nearly continuous signalling by both combatants. Males respond to play back of taped signals by flying toward the speaker and sometimes by ca lling while perched on or near the speaker. Females sometimes visit ca lling males, with copulation following very soon after the female alig hts on vegetation near the male's perch. Males increase the rate of so und production by about 11% when presented with moving pinned specimen s or paper models of conspecifics. These observations and experiments indicate that males use ultrasound as long-distance communication sign als designed to attract sexually receptive females and to establish te rritorial residency in competition with other males.