NEWPORT, Pa. -- There's a love song playing under a crabapple tree on a farm in the mountains of central Pennsylvania. After a 17-year wait, millions of male periodical cicadas are pitching woo.
Cicada mania has almost run its course in warmer, southern regions, but here it's just now reaching its peak, says Greg Hoover, an extension entomologist at Penn State University.
"This is all about mating," he said. "The best singer is going to get the girl, so to speak."
Periodical cicadas are unique to North America. The grasshopper-like insects emerge full grown after more than a decade underground. Different groups, or broods, appear in either 17-year or 13-year cycles. This year, Brood X is filling forests from Georgia north to Pennsylvania and west through the Ohio River Valley to the Mississippi.
The clumsy fliers are constantly bumping into things, and the ground is littered with exoskeletons shed when the nymphs entered adulthood.
But it's their song that makes them impossible to ignore.
Nathan Erwin, director of the O. Otto Insect Zoo at the Smithsonian Institution's National Museum of Natural History, said the cicada's body is built for pumping up the volume. The cicada moves a thin membrane called a tymbal, generating sounds that reverberate throughout its body.
"The male's abdomen is mostly hollow, so it's that abdomen that acts as that copper-kettle tympani drum," he said.
There are three species of periodical cicadas, known collectively as Magicicada. Septemdecim are largest, with orange wings and orange and black stripes across the abdomens. Septemdecula are rarest, with orange stripes across the abdomen. Cassini tend to be smaller and almost entirely black.
"Septemdecim is the whirring, spaceship-like 'whoozh, whoozh' in the background," Erwin said. "The cassini will be the sputtering, 'dut-dut-dut-dut bzzzt, dut-dut-dut-dut bzzzt.' And then septemdecula is more like the water sprinkler, 'chick, chick, chick, chick."'
This crabapple tree contains thousands of cicadas, their voices rising and falling so loud one can almost feel the noise.
"They're not some harmonious chorus, although it may sound that way at times," Erwin said. "They're basically saying, 'Hey - I'm the loudest, I'm the strongest. Baby, you want to mate with me."'