Cicadas: Rhythm of life
Music to your ears or a midsummer cacophony, the cicada’s song is inevitably short lived.
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.
These experts in camouflage use their leaf-like wings as a cover from predatory birds. Males possess a hollow, balloon-like abdomen that acts as a sound reflector to project their chorus over long distances. When a female approaches, the male begins its courtship song: a sequence of short and spasmodic chirps.
Wing length: 36–55mm.
Floury bakers, so named for the flour-like dusting that covers the bodies of newly merged adults, have adapted to a wide range of habitats: you’re just as likely to encounter these cicadas in a city garden as you are in remote bushland.
Wing length: 30–51mm.
Also known as the whiskey drinker, these cicadas emit a dawn-to-dusk rattle-like song from the upper trunks of eucalypts. The bulbous ‘nose’ houses a muscular pump used like a drinking straw to feed on eucalypt sap.
Wing length: 46–61mm.
Northern Double Drummer
One of Australia’s largest and loudest, this species can be found in the north from September to April. Nymphs emerging from the ground are coated in a thin layer of mud, which dries to become a permanent part of their bodies.
Wing length: 50–63mm.
Usually a vivid lime-green colour, greengrocers occasionally wear yellow, tan or blue coats. Males produce a shrill, ear-splitting song – at close range the volume can approach 120 decibels; equivalent to the level of a nearby speeding train.
Wing length: 50–58mm.
These long-lived Apple Islanders thrive in the cold and are incapable of the high trilling of other cicadas, instead producing a low-intensity call that vibrates through plants. Potential mates “hear” them through sensors between the claws at the ends of their legs.
Wing length: 32–41mm.
In one summer season thousands of aptly named redeyes fill the trees; the next, they’re gone. On hot days they spend large amounts of time sucking sap from eucalypt branches and spraying clear waste fluid (which can be felt as a light sprinkle – perplexing on a fine day).
Wing length: 43–55mm.
This article was first published in the Jan-Mar 2009 issue of Australian Geographic. AG thanks Max Moulds for his assistance with this article.