They sound like shady underworld figures – masked devil, razor grinder, black prince – and their sound has been ringing out early this season.
It is a bumper year for cicadas, which have not emerged in such large numbers around Sydney and the Blue Mountains since 2006, said Dave Britton, the entomology collection manager at the Australian Museum.
Species such as green grocers – also known as yellow Mondays, chocolate soldiers, masked devils or blue moons, depending on their colour – have appeared two to three weeks earlier than in past years.
”The very early series of warm days in spring seems to have got them all out, including ones that I normally associate with Christmas time, the double drummers,” Dr Britton said.
Cicadas spend several years underground as nymphs, emerging to indulge in a ”flurry of mating”. Adults usually survive for just a few weeks.
Emerging en masse seems to deter predators, Dr Britton said. The birds ”get so sick of eating cicadas, they can’t eat another one”. Then there is their call, the car alarm of the insect world. Males can hit 120 decibels while trying to attract mates.
”It’s thought that a lot of birds give up and go away, they can’t hack the noise,” Dr Britton said. ”The cicadas have a special trick where they turn off their hearing so they don’t deafen themselves.”
David Emery, a veterinary professor and lifelong ”cicada enthusiast”, said each cicada species has its own distinct courting call. He is studying cicada biodiversity and ecology and described this as ”an exceptional year” for green grocer and masked devil numbers.
Professor Emery said the insects ”virtually herald summer”, and used to be quite valuable. ”Kids of my father’s generation used to trade them for money. They used to sell a black prince for a penny.”
Despite this year’s abundance, cicadas have been disappearing from urban areas.
Senior fellow at the Australian Museum Max Moulds said as trees and dirt were replaced by concrete and bitumen, newly hatched nymphs had nowhere to burrow and adults became trapped underground.
”They’re being forced to the perimeters of Sydney,” he said. ”In the inner suburbs, a lot of the lower north shore … they’re pretty well gone.”
The bushfires in the Blue Mountains would likely annihilate a generation of masked devils, Dr Moulds said. ”In six years there will be no cicadas in those areas. It will take them a long time to recover.”
Read article at the Sydney Morning Herald