Monday, December 7, 2009


The 'Greengrocer' Cicada (Cyclochila australasiae)

Outside my window in the evening this little fella joins with his mates to make about 150dB of shrill sound...a trilling experience to be sure. At this time of year,during the day, if you drive along any east coast road , you will suddenly come across a patch of trees which seems to be full of deafening Cicada song .The noise ends equally abruptly on leaving the patch of scrub. The main purpose of all this noise is to bring the "tribe" together and as a mating call to attract females. The female lays eggs on bark on tree branches high above the ground. She does this by sawing into the bark from a structure in her abdomen and laying 6 to 10 eggs in the slit in the bark . Many of these slits may be made , usually in a herringbone pattern along the branch.On hatching, the tiny nymphs jump off the branch to fall to the earth below. In their thousands they come showering down with a sound like rain on the leaves. Many die in the process of finding a suitable place to burrow underground to start their long life as subterranean nymphs.The most famous Cicada is a species from North America which spends 17 years underground. During this time they make themselves a little cell ,astride and piercing a rootlet as a source of food. On emerging they cast aside their old skin which is usually left behind on a wall or tree trunk as pictured below.

Through the split in the back of the cast skin something can be seen of the internal structure of the tracheae which forms the respiratory system of insects. When the cuticle is cast ,its extensions within the body are cast, too, and the linings of the tracheae trail from inside the cast skin. That is that small white curly bit in the photo. Fascinating stuff if you love cicadas and they seem to have a big fan club worldwide . I even came across a website called "Cicada Mania'.

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