Cicadas and their songs

Posted on 24 September 2012

The song of the cicada is well known in most of the warmer parts of the world. At first I believed they sang in reaction to high temperature, but they literally sing for their lives. You see, these insects live for only about two weeks, so it’s crucial to find a mate and procreate as quickly as possible. There is simply no time for elaborate courtships and soft music.

Cicadas’ songs are mostly produced by the males and consist of a series of clicks made by buckling a pair of abdominal membranes called tymbals. Their bodies amplify the vibrations so females can hear them from about 500 metres away. To humans they may all sound the same, but each species has a distinctive set of calls and females are tuned in to react only to that of the same species.

After mating, the female deposits eggs into slits in the bark of a tree, a process she’ll repeat until she’s laid several hundred eggs. Hatching seems to be perfectly planned and some cicada species match their annual life cycles to large prime numbers – probably to avoid even-numbered, predictable breeding cycles which their predators could match. Also, by ensuring trillions hatch on a single evening, they literally swamp their predators, who gorge themselves without damaging the cicada population.

Nymphs can live underground for long periods of time, feeding on the roots of trees. They also use their droppings to create waterproof cells to help protect them from flooding. Even so, up to 98 per cent perish before they feel the urge to rehatch.

Because of this apparent ability to be reborn from the ground, they have come to represent resurrection and immortality in many cultures. In Japan, for example, they are symbols of reincarnation.

They’re eaten by birds, wasps and many people around the world (apparently they’re surprisingly meaty – especially the females – and taste a bit like asparagus) and their shells are used in Chinese traditional medicine, but spotting a cicada isn’t easy. These nondescript insects, which are related to leafhoppers and spittlebugs, look a bit like overgrown flies. They’re well-camouflaged, so while you may hear them easily you’ll have to look carefully to find them on branches in trees where they make the most of their short life by feeding, singing and mating.

Fascinating facts about cicadas

  • People in ancient Greece kept cicadas as pets and philosopher Plato once told a story of how these insects were men whose devotion to song was so great that they wasted away, leaving behind only their music.
  • French entomologist Jean-Henri Fabre believed that cicadas were deaf because they didn’t react when he fired a cannon towards them. Now we know the cicadas were probably ignoring him because they’re only tuned in to hear the sounds of their mates calling.


Source:
The Pocket Book of Animals by John Lloyd and John Mitchinson (Faber and Faber, 2009).

 






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