The hot days and balmy nights of summer wouldn’t be the same without the chirruping of cicadas. It’s the males that make all that noise – they are often visible on lamp posts and tree trunks. But they have actually spent most of their lives in the dark, deep underground.
Full story by John Marris
Main image: Chorus cicada
The Short Story
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Cicadas have a wide head, big eyes, four wings and six small legs. Unlike other singing insects, such as grasshoppers and crickets, cicadas do not have large hind legs for jumping.)
New Zealand species
New Zealand has 42 unique species and subspecies of cicada. The biggest is the chorus cicada, with a wingspan as wide as your palm. In summer, the males sing in chorus for a mate.
Different species live all around New Zealand, from forests and grassland, to swamps, sand dunes and riverbeds. The chorus cicada also lives in cities, perching on fence posts and buildings. The small, black Maoricicada species are the only cicadas known to live high up in the mountains.
Cicadas spend most of their life underground, and emerge to become adults. You might see their empty skins on tree trunks.
- The female lays her eggs on plants such as grasses or trees.
- Cream-coloured nymphs hatch out. With claw-like legs they dig about 40 centimetres down into the earth.
- Underground, they shed their skins several times as they grow. Most species stay there for three years or more, and then burrow back up to the surface.
- Then, at night, the nymph climbs a tree or other support, and its final skin splits open.
- The adult comes out, with crumpled wings. In the morning it flies away.
- The adults mate, and the females lay their eggs. Adults live for two to four weeks.
Under the soil, nymphs suck sap from plant roots, using needle-like mouthparts. Adults also feed on sap.
Only male cicadas sing, to court females. The sound is made by membranes known as tymbals on each side of their abdomen. The tymbal is pushed out, causing a burst of sound. Then it pops back in. By rapidly repeating this, the cicada makes its song. Some New Zealand cicadas also make clapping sounds by flicking their wings against the branch on which they are sitting.
Both males and females have hearing membranes called tympana. Through these they hear the sound of the males.
Predators and other threats include wasps, beetles, fungal parasites, birds and spiders.