.STRUCTURE IS Curing Americans to all sort of eyeglasses. On April 8th thousands saw a total solar eclipse. Numerous will certainly be actually much less mesmerized when, in the coming times, mountains of cicadas seem in the country's Midwest and also south-east. The throng will definitely be actually unusually sizable given that two types of the pest-- Brood XIII and Brood XIX-- are developing concurrently. The final opportunity they seemed simultaneously remained in 1803, when Thomas Jefferson was head of state. Why perform the cicadas possess such an unusual life cycle?