.TYPE IS TREATING Americans to all sort of spectacles. On April 8th millions watched a total photovoltaic eclipse. Several will be much less mesmerized when, in the coming times, mountains of cicadas show up in the country's Midwest and also south-east. The flock will be extraordinarily large because two kinds of the pest-- Brood XIII and Brood XIX-- are actually emerging all at once. The last opportunity they showed up simultaneously remained in 1803, when Thomas Jefferson was head of state. Why perform the cicadas have such an unique life process?