One of my least favorite sounds is the screeching call of the cicada. The cicada is an insect that makes long and loud calls, usually in the summer. Once you've heard this sound, you never forget it because it's loud (some are known to reach 100 decibels) and it's never just one cicada going: it's many. But why are there many, and what causes this annoying sound?
You can usually find these loud insects in trees high off the ground to allow their songs to travel farther. Why? Because the songs are actually mating calls. They attempted to emit the loudest and longest song possible to try to attract a mate. Only the males make this sound.
The sound is produced by two membranes in their abdomen called tymbals. They contract a tymbal muscle which causes the two membranes to rub against each other. It's rubs once and makes a click. When the muscle relaxes back, it clicks again. These tymbal muscles can contract and relax very fast, which causes the sound we hear. However, it isn't that loud. Hollow air sacs in the abdomen amplify the sound. The tympanum further amplifies the sound, and the 100 decibel song is on.
The female cicadas will respond with what can be called a 'wing flick'. Cicadas have great eye sight, so if the female is close, he can probably see her. But just in case, her wing flick gives just enough sound for him to find her. They find each other and together the call and wing flick become a courtship call.
It's possible that if you startle a cicada, it will give a warning call. Oddly enough, this sounds just like the mating call. Either way, the sounds cicadas make are rather disturbing.
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