communication of cicadas

The cicada exemplifies an insect species which uses a combinatorial system. In the cicadas’ life cycle, communication is very important, for only through the exchange of sounds do they know where to meet and when to mate. Three different calls are employed for this purpose. Because of their limited sound-producing mechanisms, cicadas can make only ticks and buzzes. The only way they can distinguish between congregation and courtship calls is by varying the rate with which they make these ticks and buzzes.

The congregation call consists of 12 to 40 ticks, delivered rapidly, followed by a two-second buzz. It is given by males but attracts cicadas of both sexes. Once they are all together, the males use two courtship calls. The preliminary call – a slow, prolonged ticking – is given when the male notices a female near him. Then, the advanced call – a prolonged series of short buzzes at the same slow rate – is given when a female is almost within grasp. Although the preliminary call may be omitted if a female is suddenly discovered very nearby, it almost invariably occurs before the advanced call. So, during typical courtship, the two calls together result in a ticking followed by a buzzing – the same pattern which comprises the congregation call, but delivered at a slower rate.

In this way, cicadas show efficient use of their minimal sound-producing ability, organizing two sounds delivered at a high rate as one call and the same sounds delivered at a slow rate as two more calls.

Basic Facts: Insect Communication
http://www.insectzoo.msstate.edu/Students/basic.communication.html