STATE COLLEGE, Pa. - After 17 years of relative quiet, Mother Nature is bringing the noise. Periodical cicadas, a species of the grasshopper-like insects best known for the scratching, screeching "singing" of the males, will emerge this May, filling forests in more than a dozen states. Almost as abruptly as they arrive, they'll disappear underground for another 17 years. "Why do certain insects take only one year to develop, and others take two or three? It's just part of their genetic programming," said Greg Hoover, senior extension entomologist for Penn State University. There are at least 13 broods of 17-year...