This striking object is the cast skin of a cicada nymph. It sits on a fern, discarded. A testament to a life spent underground; large fossorial fore-legs, adapted to digging the subterranean burrows in which it has lived for so many years, toiling away at the soil, excavating and supping – sucking hard – on weak sap in its underground chambers. On a diet of watery xylem, the cicada nymph has grown slowly, but after many long years – how long we don’t know for some species – comes a time for change. Not a complete metamorphosis – these are hemimetabolous insects – but a dramatic, earth shattering change, nonetheless. The first step is to that of the nymphoid stage; a short-lived (c. one month) period in which it prepares to become an adult. Eventually this nymphoid larva crawls up and out of the ground, into the light, its unblinking eyes searching for a stem or tree trunk to crawl up on. Then, after a few hours in this new world, the adult starts to emerge.
Slowly, over the course of a few hours, the imaginal (adult) stage emerges, breaking out of the nymphoid larva, a second birth through the thorax. A natural, cicadian caesarian – a term coined by Michel Boulard (1) – through a dorsal opening called the ecdysial cleavage line. Slowly, the adult pushes itself out – an imaginal hatching – through the hole in the thorax, leaving behind a dried husk (the exuviae).
Soft and vulnerable, the adult cicada remains clinging on to the residue of its former self for many more hours as it slowly hardens. This final process of stiffening is delightfully called: imagination. This process of emergence and final development has been captured in beautiful detail here (downloads), for a species called Chremistica umbrosa, in Singapore (2).
There is much more that could be written about the lives of adult cicadas – their songs, their reproduction, their feeding, their enemies – but I will leave that for another blog.
- Boulard, M. (2007). The cicadas of Thailand: general and particular characteristics. White Lotus.
- Tzi Ming Leong, Aminurashid and Benjamin P. Y-H. Lee (2011). Records of the cicada, Chremistica umbrosa (distant, 1904) in Singapore, with accounts of its mass emergence (Homoptera: Cicadidae: Cicadinae). Nature in Singapore 4: 163–175.
I am a retired entomologist with a background in quarantine pests and invasive invertebrates. I studied zoology at Imperial College (University of London) and did a PhD on the population dynamics of a cereal aphid (Metopolophium dirhodum) in the UK. I spent 5 years with the British Antarctic Survey studing cold hardiness of Antarctic invertebates and 17 years with the Food and Environment Research Agency. My main interests now are natural history, photography, painting and bird watching.