NASHVILLE, Tenn. — As 17-year periodic cicadas scratch and buzz in 13 states, entomologists remind us that brash noise is really an insect love song.
"It's the men's glee club serenading the ladies," said Dr. Frank Hale, with the University of Tennessee Extension in Nashville. The current emergence is Brood XIV, and it stretches over 13 states from Georgia to Massachusetts. The periodic cicadas are a phenomenon of the hardwood forests of the eastern U.S.
While cicadas get turned on by the sound they emit from two drumlike membranes on the abdomen, humans find it shrill, loud and annoying.
But listen carefully, advises Greg Hoover, an entomologist at Pennsylvania State University in State College. You'll hear different songs because there are three different species in Brood XIV.
"The more common species sound as if we were to pronounce 'Pharaoh' and extend it at the end," Hoover said. "Then there's another that's a series of ticks and buzzes, and yet another sounds like a water sprinkler."
The female cicadas' response to this courting is subtle. A demure flick of wings indicates a female is ready to mate, Hoover said.
Beyond the noise, people can be unsettled by the 1.5-inch (3.8-centimeter) bugs' red eyes (except for rare white-eyed ones), their clumsy flight and what Hoover calls their tendency to assume anything upright is a landing spot.
But cicadas can't bite or sting even when they light on you, he assures.
Unique to eastern U.S.
Periodic cicadas — the insects people sometimes call 'locusts' — are unique to eastern North America.
"The (American) colonists thought they were witnessing a locust plague," Hoover explained.
Weirdest science storiesLocusts, however, are more like grasshoppers, which eat grasses and crops, Hoover said. Cicadas suck nutrients from trees, but usually do little damage.
The visible life of cicadas seems unmercifully short.
The adults emerge from the ground, sing, mate and die, all within a few weeks.
The new cycle begins when the nymphs hatch in twigs up in the trees, fall to the ground and burrow in. They will feed on the roots of the trees for the next 17 years.
And what's the point of all of this?
"The whole idea in nature is to reproduce," Hale said.
Burrowing in the ground also protects the nymphs from predators.
Benefits to nature
While it's true that tender young trees can be damaged by the cicadas, the insects also provide benefits to nature.
The holes from which they emerge aerate the soil around the tree roots, Hale said. The millions of decaying cicada bodies supply nitrogen and other nutrients, which rain washes down the holes to the tree roots.
For birds and other small animals, the cicada emergence is a smorgasbord.
Regardless of how much predators gorge themselves, the cicadas will prevail.
"Their strategy is to overwhelm by their numbers," Hale said. "It's 'shock and awe.'"
Cicadas are very social. The males aggregate to sing, and the females are attracted to the sound. Because of this aggregation tendency, both sexes are attracted to noisy machines like lawn mowers and farm tractors.
Brood XIV is making its appearance in at least parts of Georgia, Kentucky, Indiana, Massachusetts, Maryland, North Carolina, New Jersey, New York, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia.
While some people might see the cicadas as an annoyance, Hale has a decidedly different view.
"This is the best time ever for an entomologist," he said, explaining it's a great educational opportunity and people get to see something they won't often witness.
People who don't get their fill of cicadas this year will have to wait for the next wave of periodic cicadas, Brood XIX, which is due to hatch out in 2011 in line with a 13-year reproductive cycle.
Brood XIV will rise again in the year 2025.
This report was supplemented by msnbc.com.
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