.STRUCTURE IS Curing Americans to all kinds of eyeglasses. On April 8th thousands experienced a complete photo voltaic eclipse. Numerous will certainly be less mesmerized when, in the coming times, trillions of cicadas seem in the nation's Midwest and south-east. The throng will be uncommonly sizable due to the fact that two sorts of the insect-- Brood XIII and Brood XIX-- are emerging all at once. The final opportunity they appeared all at once was in 1803, when Thomas Jefferson was actually head of state. Why do the cicadas have such an uncommon life process?