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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 cicadas, plus another five broods that emerge every 13 years. The last to emerge, Brood IX, was seen last spring in parts of West Virginia, Virginia and North Carolina.
This year, it's time for Brood X, the so-called "Big Brood," to surface. Its range stretches from Georgia, west through Tennessee and to isolated pockets of Missouri, north along the Ohio Valley and into Michigan, and east into New Jersey and New York.
"This is one of those years we kind of dread," said Paris Lambdin, professor of entomology and plant pathology at the University of Tennessee. "We had an emergence a couple years ago around Nashville, but nothing like what we expect this one will be."
No other periodical cicada covers so much ground. And with hundreds of them per acre in infested areas, the noise will be hard to miss.
"In 1987, coming back from the University of Maryland on Interstate 95, when you drove through a wooded area you could hear the insects," Hoover said. "This would have been mid to late June, with the windows down, and then it would shut down when you got to a field or a non-wooded area."
In rare years, a 13-year brood can emerge to add its collective voice to that of a 17-year brood.
"Out in the Midwest is where things get really hairy," Hoover said. "Missouri, Illinois, Indiana have combinations of 17-year-brooded individuals and 13-year-brooded individuals, and they can have overlap."
There's no question that the class of 2004 will be a nuisance. The cicadas will make plenty of noise, and adults are poor fliers that tend to bump into things.
But as swarms go, these cicadas aren't that bad. Adults don't feed on leaves, so they won't strip the trees, but they do lay their eggs in twigs.
"The females, once mated, will lay pockets of eggs along twigs that will cause structural weakening of those twigs," Hoover said. "Eventually they may drop off and fall to the ground, the nymphs will drop off and fall to the soil, and that's where this species is for the next 17 years."
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