Incredible time lapse video of the Metamorphosis of a green cicada Cicadas are both fascinating and complex in their looks, their variety (more than 3,300 species worldwide) and their life cycle - there are both annual and "periodic" types, which appear only in certain years, based on a biological cycle. Cicadas reside underground for anywhere from one to 17 years, feeding on roots, before emerging as nymphs that go on to shed their exoskeleton and become adults. In many species they live no mor