Cicadas: Rhythm of life
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.