Cicadas sing most actively in hot weather and do their most spirited singing during the hotter hours of a summer day, in a roughly 24 hour cycle. Some cicadas can produce sounds up to 120 dB (SPL), among the loudest of all insect-produced sounds. This is especially notable as their song is technically loud enough to cause permanent hearing loss in humans, should the cicada sing just outside the listener's ear. In comparison some small species of cicadas produce such high-pitched calls that the noise produced is beyond the hearing range of a human. Only male cicadas sing in order to find a partner, but the singing of cicadas can vary in differing situations. Their call is also used to express alarm, and scare off or reduce the effectiveness of attacks from predators. Some species that tend to be weak fliers only sing at dusk to gain protection from predatory birds by confining their activity. Jean Henri Fabre (1823-1915), a French entomologist famous for his study of insects, questioned the reason behind the drone of cicadas. In Fabre’s Book of Insects, he speculates, “Whether drinking or moving they never cease singing. It seems unlikely, therefore, that they are calling their mates.You do not spend months on end calling to someone who is at your elbow. ”The insect enthusiast conducted an experiment where he fired two guns near the resting site of multiple singing cicadas. After the thundering claps of artillery being fired, the cicadas were not in the least disturbed and never took the time to take a break
nd in their concerto. He concluded, “I think, after this experiment, we must admit that the cicada is hard of hearing, and like a deaf man, is quite unconscious that he is making a noise”. While the unrelenting singing of the cicadas can feel like an irritating record on repeat, the timing of the cicada’s singing can also act as a useful indicator. In the Javanese version of cycle of months, called pranata mangsa, the cicada sound is used as an indicator of the beginning of dry season (April–May). Farmers who still depend on rain irrigation will interpret this as time for planting of non-rice crops.
Jean Henri Fabre (1823-1915), a French entomologist