By Mark Horstman
They have colourful names like Yellow Monday, Blue Moon and Masked Devil and they’re the world’s loudest insect.
Cicadas let us know they’re there with their deafening noise, but they’ve kept much of their life a big secret.
We don’t know about their life span, or even how many types there are in Australia.
“Cicada diversity here is amongst the highest in the world,” says Lindsay Popple, who’s an insect expert at the Queensland Museum and one of the few scientists who study cicadas.
“More than 300 species of cicadas have been described. There could be somewhere between 700 and 1,000 species in Australia once we’ve discovered them all.”
Dr Popple became fascinated by the calls of cicadas as a teenager.
“I love the thrill of hunting cicadas by following their sound, quietly stalking them, and catching one to get a closer look,” he says.
Deafening summer soundtrack
Large cicadas such as the Double Drummer, which are often heard around Sydney, are louder than a jet engine!
The cicada makes the sound with “tymbals” that are like two speakers, one on each side of its body.
Tymbals make a snapping noise when muscles pull them in and out. The cicada does this several hundred times each second and the vibrations make a chirping, buzzing or drumming sound.
Each species has its own song, and only the males make mating calls. The females respond with a wing flick, like a snap of the fingers, which lets the male know where she is.
Growing in total darkness
After females lay their eggs into a plant stem, small wingless cicadas called nymphs hatch, fall to the ground, and start burrowing.
We know adult cicadas live for just a few weeks but in Australia we don’t know how long they live as nymphs. It’s thought it could be between four and 10 years.
They dig long tunnels in total darkness to find tree roots and suck their sap, shedding their skins as they slowly grow.
When conditions are just right, the nymph comes to the surface and sheds its skin for the last time to emerge as an adult winged cicada.