Summer nights in Charleston often echo with a soft, high-pitched buzz that many people assume are crickets in the distance. In fact, this background music on balmy evenings comes from the Cicada (pronounced Sikaduh), a curious-looking critter with a fascinating lifestyle. Charleston's version of this entertaining insect is called the Periodical Cicada, because it only appears periodically, after long stretches of incubation. Each Summer, female Cicadas dig into tree bark and lay eggs. When hatched, the molting “nymphs” burrow underground, absorbing nutrients for as many as 17 years before re-emerging as winged adults. The heat of the Summer stimulates the Cicadas into action, and they have only a matter of months to mate and start the process all over again.
The familiar sound is a mating sound made by the male Cicada, who rubs of section of vertebrae called tymbals in order to attract and court a female. Cicadas in 2011 have hatched by the billions, according to biologists, so the sounds are very distinct that lover is in the air. In a few months, all will be quiet, as a new generation has been deposited, and waits its turn in the line of years of nymphs ready to hatch.
Fortunately, Cicadas don't bite humans, and are typically more on the menu for birds and other creatures. Even though they have wings, they are not inclined to do much flying, and typically cling to trees to make their sounds. Just by virtue of the fact that billions are all around us, and yet we rarely see them, shows how unobtrusive they are and how much they're being eaten.
One very interesting aspect of the Cicada symphony that fascinates scientists is the variance of decibel levels and speed of the insects' noise generator. Increased levels of the chirping sound have been shown to correspond to increases in temperature, so the Cicada is in effect, a living thermometer.
