Cicadas are insects that belong to the Order Hemiptera which includes all insects with piercing and sucking mouth-parts such as bugs and aphids. There are over 200 species of cicadas in Australia and over 2,500 globally.
Characteristics of a Cicada
Adult cicadas have two pairs of wings that have a wingspan of between 2.5cm to 15cm. The wings fold back along the insect’s body when not in use. The fore wing, which is longer, covers the shorter hind wing. The fore wing is usually transparent or opaque and is strengthened by a series of thin veins. The cicada has large compound eyes situated on either side of the head and three very small eyes (ocelli) located on top of the head. They have three pairs of legs and small bristle-like antennae (feelers). The mouthparts of the cicada are used to pierce the surface of plants to suck out the juices and nectar.
Cicadas are sometimes known as locusts in Australia. The sound or singing of the cicada is produced only by the male and is the loudest sound in the insect world. It is a mating call that attracts the female. Each cicada has its own distinct sound that only attracts the female of its own species. Tymbals are the organs that produce the sound and are located at the base of the insect’s abdomen. The timbals are vibrated by strong muscles to produce their song.
The lifecycle of a Cicada
The cicada has three stages of development the egg, the nymph and the adult. Cicadas spend most of their life underground as nymphs. The Australian cicada nymphs can live for up to 7 years underground and the Periodical cicada nymphs of North America can live for up to 17 years underground. The adult cicadas only live a few weeks after emerging from their underground home. Their role is to mate and lay eggs before dying. The eggs are laid in plant stems or trees where they eventually hatch into small wingless cicadas known as nymphs. The nymphs fall to the ground and burrow underground where they live and feed on plant roots. The nymphs burrow between 5- 46cm underground. They shed their skin periodically whilst underground as they grow because their skin does not stretch. After the nymph is fully grown it digs its way to the surface using its front legs and climbs on to a tree to shed its skin for the last time. The nymph emerges as an adult cicada with wings.
Interesting Facts About the Cicada
The oldest cicada fossil found dates back to the Cretaceous Period some 65 million years ago. In 1759 Swedish scientist, Carolus Linnaeus recognised and named the insect “Cicada septendecim”.