Cicadas: Rhythm of life

Music to your ears or a midsummer cacophony, the cicada’s song is inevitably short lived.

The cicada mating song

Nothing signals the arrival of summer more recognisably than the trill and hum of cicada song. Australia’s 237 species of cicada are found nationwide – coastal bushland, suburban gardens, alpine snowfields – although they favour warm tropical areas because of the variety of vegetation types. A cicada’s song is actually its mating call: an adult male sings to attract a female, which can’t produce a song of her own. Muscles in the male’s abdomen contract to produce the racket we hear, and each species is identifiable by its unique tune. Their crescendo deters birds, a cicada’s primary predator – another benefit of being the noisiest insect on earth by decibels.

After mating, female cicadas deposit several hundred eggs into slits made in grass stems or in the bark of a tree or shrub. A few weeks on, flea-like young (nymphs) hatch and drop to the ground, then tunnel into the soil. Here they live for at least a year, feeding on sap from small roots and developing in preparation for their open-air debut. On emergence, mature nymphs shed their skins, the delicate brown remnants of which can be seen on tree trunks, grass stems and, once collected, kids’ T-shirts. But a cicada’s time in the sun is fleeting – after a nymph phase sometimes spanning several years most adults live for only a few raucous weeks.

Source: Australian Geographic Jan - Mar 2009

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