Strength in numbers is the key to cicada survival: There are so many of them that the birds can't possibly eat them all, and those that are left over are free to multiply, Raupp says.
But why only every 13 or 17 years? Some scientists think they come out in these odd cycles so that predators can't match the timing and be waiting for them in huge numbers. Another theory is that the unusual cycles ensure that different broods don't compete with each other much.
And there's the mystery of just how these bugs know it's been 17 years and time to come out, not 15 or 16 years.
"These guys have evolved several mathematically clever tricks," Raupp says. "These guys are geniuses with little tiny brains."
Past cicada invasions have seen as many as 1.5 million bugs per acre. Of course, most places along the East Coast won't be so swamped, and some places, especially in cities, may see zero, says Chris Simon of the University of Connecticut. For example, Staten Island gets this brood of cicadas, but the rest of New York City and Long Island don't, she says. The cicadas also live beneath the metro areas of Philadelphia, Baltimore and Washington.
Scientists and ordinary people with a bug fetish travel to see them. Thomas Jefferson once wrote about an invasion of this very brood at Monticello, his home in Virginia.
While they stay underground, the bugs aren't asleep. As some of the world's longest-lived insects, they go through different growth stages and molt four times before ever getting to the surface. They feed on a tree fluid called xylem. Then they go aboveground, where they molt, leaving behind a crusty brown shell, and grow a half-inch bigger.
The timing of when they first come out depends purely on ground temperature. That means early May for southern areas and late May or even June for northern areas.
The males come out first -- think of it as getting to the singles bar early, Raupp says. They come out first as nymphs, which are essentially wingless and silent juveniles, climb on to tree branches and molt one last time, becoming adult winged cicadas. They perch on tree branches and sing, individually or in a chorus. Then when a female comes close, the males change their song, they do a dance and mate, he explained.
The males keep mating ("That's what puts the `cad' in `cicada,'<!p><#148> Raupp jokes) and eventually the female lays 600 or so eggs on the tip of a branch. The offspring then dive-bomb out of the trees, bounce off the ground and eventually burrow into the earth, he says.
"It's a treacherous, precarious life," Raupp says. "But somehow they make it work."