Story: Cicadas

Entomologist Charles Fleming searches for small black cicadas of the Maoricicada genus in Otago’s Old Man Range. During the 1960s and 1970s he, his wife Peg, and entomologist John Dugdale carried out extensive surveys of cicadas. Fleming noted that the distribution of cicada species was linked to areas of scrub refuges during the last glaciation. The cicadas had survived on isolated outcrops that were not wiped clean by ice, and they were still centred on those sites. Cut off from other populations of the same species, the separated populations evolved independently into distinct forms.

Listen to Charles Fleming discuss his study of cicada calls.

Transcript

Some cicadas, a group of three, including the one that introduced this programme, supplement that song with a clicking of the wings. The two wings are raised very rapidly and snapped back and they make a noise just like snapping of fingers. Something like that. And our New Zealand three species that do that are the only three cicadas in the world that combine their ordinary song with this clicking. So they've been made a special group. Now in all the others they sometimes move the wings and make a very hardly audiable noise by doing so. But on the whole the song is made by the timbals clicking in and out very rapidly and there's different ways this can happen that two sides can be either strictly in time or they can alternate and I've had a lot of fun slowing down the songs and studying them with an oscillograph provided by the physics and engineering laboratory and studying the detailed anatomy of the song of these closely related kinds.