Cicadas

Quicklink – ELZ Cicada List

Cicadas in the Bend – Frank Pierce

On some hot summer days, the cicadas are so loud that they hurt your ears.

In spring of 2013 I decided to investigate the Cicadas in the Environmental Living Zone (ELZ). I obtained the 1990 reference – Australian Cicadas by M. S. Moulds. This had 202 species for Australia and, working through the distribution maps indicated that there were 14 possible species for the ELZ. That 2013 summer I recorded 7 species. Now, after 8 seasons, my tally is 10 species.

In 2016 I discovered the Cicadas of Australia Website. This had expanded the Australian species tally to about 400, and it is now up to about 700 species. Some predict this total will rise to 1000+.

Cicada lifecycle

The life of adult cicadas is very short, lasting only a few weeks. After mating, the adult female cicada lays its eggs. It does this by piercing plant stems with its ovipositor (egg-laying spike at the tip of the abdomen) and inserting the eggs into the slits it has made. The eggs hatch into small wingless nymphs that fall to the ground and burrow below the surface. Here they live on the sap from plant roots for a period which may last several years. They shed their skin at intervals as they grow. When the nymph reaches full size it digs its way to the surface with its front legs, which are specially adapted for digging. It generally surfaces about nightfall in late spring or early summer. The nymph then climbs on to a tree trunk or other object and sheds its skin for the last time. The fully-winged adult cicada which emerges leaves its old empty nymphal skin behind.

Cicada facts:

  • Only male cicadas sing. They do this in an attempt to find a mate.
  • The sound produced by some communal species can act as a defence against predators
  • Different species have different songs to attract only their own kind
  • They often sing in chorus making it more difficult for predators to locate individuals
  • Adult cicadas have short lives, usually only a few weeks.
  • Most of their lives are spent as nymphs underground for up to several years – 6 or 7 years for Greengrocers
  • Cicadas feed only on plant sap using their piercing, sucking mouthparts.
  • Cicadas feed on a huge range of plants, including eucalypts and grasses.
  • Birds, bats, spiders, wasps, ants, mantids and tree crickets all prey on cicadas.
  • They are classified in the order Hemiptera, which includes all insects with piercing and sucking mouth-parts.
  • wing spans of the different species range from about 2.5 cm – 15 cm
  • Cicadas have a pair of large compound eyes, and also three very small glistening simple eyes (ocelli) on the top of the head.

Cicada Singing

Cicadas are notorious singers. The song is a mating call produced by the males only. Each species has its own distinctive call and only attracts females of its own kind even though rather similar species may co-exist.

Cicadas are the only insects to have developed such an effective and specialised means of producing sound. Some large species such as the Greengrocer/Yellow Monday and the Double Drummer produce a noise intensity that is approaching the pain threshold of the human ear. In contrast, some small species have songs so high in pitch that the noise is beyond the range of our hearing.

The organs which produce sound are the tymbals, a pair of ribbed membranes at the base of the abdomen. Contracting the internal tyrnbal muscles causes the tymbals to buckle inwards and produces a pulse of sound. By relaxing these muscles, the tymbals pop back to their original position.

For more details see Australian Museum

References