.STRUCTURE IS ACTUALLY TREATING Americans to all sort of eyeglasses. On April 8th millions witnessed a complete photovoltaic eclipse. Several will certainly be actually much less charmed when, in the coming days, mountains of cicadas show up in the country's Midwest as well as south-east. The throng is going to be abnormally huge given that two kinds of the pest-- Family XIII and also Family XIX-- are developing concurrently. The last opportunity they appeared together was in 1803, when Thomas Jefferson was actually president. Why do the cicadas have such an unusual life cycle?