Early summer days in this part of Australia ring with sound of cicadas:
These extraordinary little creatures spend years underground before popping up to find a mate by climbing into the nearest tree. (Good David Attenborough dialogue, don’t you think?)
It’s the males that call – the females are silent but respond to a male by flicking their wings. For such a small critter the noise level they produce is incredible – over 100dB from around a metre away from just one insect.
I decided to record the sound and analyse it. To my surprise, this is what the spectrum looked like:
What’s surprising is that no natural oscillator I have ever seen has a gap in the spectrum, as you see here (between 600 and 800Hz). The only conclusion possible is that there there are two quite different species calling at the same time, most likely a bigger one in the lower frequency and a smaller one in the higher.
The two likely types are what are commonly called greengrocers and black princes. I have no idea which call is which…
This is a black prince: