Why cicadas are louder this year
Anyone who's been outside in the last month may have noticed the loud buzz of cicadas and while there isn't an exact count of how many there are, a specialist has confirmed that "there are a lot more out there than usual".
Dr Michael Elias, from the CSIRO's Australian National Insect Collection, told 9News that part of the origin of this year's cicada crop may date back to the 2017-2019 drought.
Cicadas have a life cycle of six to seven years, with the eggs laid by adult cicadas in the soil surviving on sap on tree roots. They need wet conditions to survive, and because the drought ended, more of them are now able to thrive.
"I think what's causing it is partly, if you think about the amount of rainfall we've had this century, (we) started off in a bit of a drought there, and then had a few rain years, and back into drought," Elias said.
"There was another drought that ended in different parts of Australia between 2017 and 2019," he continued.
"So that was about seven years ago now, five to seven years ago, that that drought ended.
"So the cicadas are becoming more noisy than they have been for quite a while, just because we haven't really had a good patch of seven years."
The wetter conditions over the last few years have ensured the trees and roots they need to eat are abundant.
"It's really probably just the fact that the ground is very wet, so there's a lot of tree roots out there for them to feed on," Elias said.
"So you're getting lower mortality in the juveniles."
He added that "it is possible that we're getting multiple generations emerging this year, just because we've had a few warm years."
Adult male cicadas are the ones that make all the noise as they rub their wings against a membrane on their back to attract a mate.
Cicadas can produce a noise intensity of up to 120 decibels, which is equivalent to the sound of thunder or a jet plane taking off.
Australia has about 250 described species of Cicadas, with potentially 500 to 1000 undescribed species of the insects.
"The level of our knowledge of the insect ecosystems is well below what the common person thinks it is," Elias said.
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