‘Chrrrr-chrrrrr-chrrrrr-chrrrr . .’ This time of year there is no escaping it – unless you are immersed in the ‘Whrrrr-whrrrr’ of an air-conditioner, that is! I’m talking about the incredible sound of cicadas; amazing creatures that fill the night (and the day) with their incessant conversation. Rising and falling in volume and then suddenly, as if at some hidden signal, all switching off in unison, making the silence sound incredibly loud! After a few seconds an individual will be unable to contain itself, ‘Chrrrr-chrrrr’, swiftly answered by another, and another until the air is filled with their sound once again.
Considering how many of these creatures surround us, even in towns and cities (as long as there are trees), we see very few of them about the place. Some of the folks I know have never seen one at all! Try and track down these susserrating bugs (they are related to leaf-hoppers and spit-bugs) and they are guaranteed to spot you before you spot them and shut up instantly, only to start up again as soon as you turn your back and walk away! Unlike humans, only the males of this species chunter on with the females keeping ‘mum’. They produce their sound in a different way from crickets and the like which rub ‘bits’ together – cicadas have a modified, ribbed membrane each side of the abdomen called tymbals. By rapid contractions of a muscle they are able to produce a succession of clicks. They are just about the noisiest insects around with some species able to produce sounds up to 120dB – technically loud enough to cause hearing loss in humans!
Their life-cycle is interesting; the females cut a slit in the bark of a tree and deposit their eggs. When these hatch the grubs drop to the ground and burrow in, some species spending up to 17 years there, going through numerous ‘skin’ changes in the process. Our local bugs spend 3-5 years underground before emerging, climbing whatever they can find, and going through their final shedding to emerge as a fully developed cicada.
Cicadas are harmless to humans, using a proboscis to suck sap – although there are reports of the occasional dimwit mistaking a bit of human anatomy for a tree and getting stuck in! With around 2500 species world-wide, on every continent apart from Antarctica, they are remarkably successful and a fascinating study for the curious amateur biologist.
For those with the interest (and the bandwidth), here is a five-minute film about their life-cycle.
Alan Fenn, Okçular Köyü