The east coast of Australia is heading into a big, loud cicada summer.
Prof David Emery, a veterinary immunologist and cicada expert, called it a “phenomenal season so far” for green grocer cicadas, which emerged in huge numbers in the Blue Mountains in September and are now making their appearance in Sydney and parts of Victoria.
Green grocers aren’t the only species turning up in abundance.
Emery said multitudes of the largest and noisiest varieties – green grocers, double drummers, black princes, razor grinders, red eyes and cherrynoses – were also emerging along the New South Wales coast.
Australia was the “cicada capital of the world” and home to “upwards of a thousand species”, with many yet to be scientifically categorised.
“Some of the little fellas don’t make much noise, so they’re less intrusive,” he said. “But the big guys in large numbers can be quite deafening.”
Dr Lindsay Popple, a cicada researcher, said early observations and the warmer weather indicated a “pretty big summer for cicadas”.
Green grocers were usually one of the earliest, he said. “Then you get this wave of all the other species coming out. Between Christmas and New Year over the eastern seaboard, that’s a peak time for cicadas.”
The insects spent most of their life as nymphs underground. They fed on plant roots, waiting for temperature and rainfall cues to climb out of the ground, shed their exoskeleton and grow wings, he said. That was when the males began singing to attract females, which could go on for weeks.
Green grocers were thought to emerge in greater numbers on a seven-year cycle. There were likely two main batches, which explained boom years in 2010, 2013, 2017, 2020 and 2024. Less was known about the life cycles of the other species, Popple said.
Cicadas were a big part of children’s culture in Australia, Popple said, especially in Sydney which had many of the larger and louder varieties. Green grocers were particularly sought after, coming in different colours with evocative names including “yellow monday”, “masked devil” and the appropriately rare “blue moon”.
The insects produced their pulsating chorus by expanding and contracting a flexible organ called a tymbal, a sound amplified by their body structure, he said. “In big numbers, they’re incredibly acoustically conspicuous.”
Double drummers and green grocers were some of the noisiest according to the Australian Museum, which reported noise levels as high as 120 decibels at close range.
Christophe Delaire, the chief executive of Marshall Day Acoustics, said research found cicada noise measured at 50cm could range from the high 70s to more than 100dB.
That was “extremely noisy”, he said. “On a hot summer day the noise of a thousand cicadas would be deafening. You wouldn’t be able to hear yourself think.”
In the middle of the range – 90dB – cicadas could be as loud as a lawnmower, albeit with different characteristics, and much louder than conversation at 60 to 70dB.
But noise level was just one factor that acoustic consultants considered in assessing noise and acoustics, Delaire said. It was also important to consider other factors such as frequency and reverberation, and subjective elements.
“To some people the sound of cicadas may be the sound of summer, and therefore they find it relaxing,” he said. Whereas someone working on a farm, unable to communicate above the din of cicadas, may have a different perception.
In general, the closer you are the louder they sound, he said. “The advantage that you have with cicadas is once you get too close to them, they stop singing.”
