Aussie Summer Concert
It’s not an Aussie summer without the deafening concert of thousands of cicadas. Around October, you can see the first empty shell of a newly hatched cicada on a tree trunk or your fence.
They will soon fill the air with their song before they disappear again for winter. But where have they been during the colder months?
At the end of summer, each female cuts small slits into plant stems and branches and places her eggs inside. From these eggs nymphs hatch, which drop to the ground and dig themselves into the soil.
They find a root, attach themselves and start sucking the sap. Some species remain in this state for a few months; others stay underground for years.
On the first hot days of late spring or early summer, especially after rain, the nymphs will make their way to the surface. They climb up a vertical object, often the tree on which they were born and that they have been feeding on, and shed their shell.
A new cicada has emerged, ready to join in the summer chorus. It is now a winged insect with a wing span of up to 2 centimeters and a pair of drum-like organs called tymbals, which they use to sing their song.
DID YOU KNOW?
Each species of cicada has its own distinct song to attract only the right partners to mate with. Some species can sing as loud as 120 decibels, louder than a chain saw, and about as loud as a plane on an airport runway.
Every summer, museums and local councils around Australia are inundated with desperate phone calls. “Please do something!” they appeal as the shrill song of Greengrocer, Yellow Monday and Double Drummer cicadas fills the air, making the hot summer days even more unbearable.
But there’s little anyone can do about cicadas when they are on the hunt for love.
After spending up to seventeen years underground, the male cicada has just a few weeks to find a mate, and he is unstoppable. While his piercing call can reach up to 120 decibels – the human pain threshold – it is perfect for both attracting the girls and repelling hungry birds.
But next time cicadas are driving you nuts and you are reaching for the earplugs, consider this: biologists say cicadas are so plentiful and nutritious, they are thought to form the foundations of the terrestrial food chain. Without them there would be no plants, no birds, no frogs, no reptiles and ultimately no us!
Cicada nymphs dig their way to the surface with their front legs which are specially adapted for digging. They generally surface at nightfall in late spring or early summer when they climb on to a tree trunk and shed their skin for the last time. The fully-winged adult leaves its old nymphal skin behind.
DID YOU KNOW?
Cicada movement and behaviour is being used as a yardstick to measure climate change. Some northern Australian species are turning up in Victoria, others are breeding later in the year, and in the United States, they are emerging from the ground years ahead of schedule.