What Makes Cicadas So Loud?

With the 17-year periodic cicadas emerging across a wide swath of the country, The Daily Green invited the authors of The Songs of Insects (Houghton Mifflin) to tell us how it is those little bugs have such big voices. Click the link below to hear what people in the Midwest are hearing, or read on to learn how Brood XIII makes such a buzz. Click Here To Hear The Otherworldly Song Of The 17-Year Cicada A Concert of Cicadas By Wil Hershberger For The Daily Green What is making all that noise coming from the treetops? Could it be the work of those large black insects with orange wings and red eyes, that we see crawling around on limbs and leaves? Yes, these are the 17-year Cicadas—and what a spectacle of sight and sound they provide! Also called "periodical cicadas," these scary-looking but harmless insects (they do not bite or sting) have spent 17 years underground developing and growing. As the soil temperature reaches about 64 degrees, the brown nymphs emerge en masse over just a few days. As if by magic, tens of thousands may suddenly appear in a small woodlot, the nymphs crawling out of their burrows and then climbing anything that they encounter. At some point they stop, and then over a period of hours, each adult sheds its nymphal skin, dries itself out, and then climbs or flies into the treetops to search for a mate. 17-year Cicadas are members of the Order Homoptera. They eat by sucking the sap from plants. Cicadas are among the loudest of the singing insects of North America (see www.songsofinsects.com for song samples of a variety of species). The 17-year Cicada is special because males have several different songs. Click Here To Hear The Otherworldly Song Of The 17-Year Cicada The most commonly heard is the calling song, a slowly repeated buzzing "whee-ooh" that drops in pitch at the end. Large numbers of males congregate in the crowns of deciduous trees and sing together—and the loudness of their combined effort can be hard on the ears. The chorus sounds otherworldly, like something out of a science-fiction movie. Once a male is close to a female, he sings an animated courtship song consisting of a rapid series of "whee-ooh" calls all slurred together. Then, just before mating, he gives an excited series of staccato "whap" notes that seem to excite his mate. Once mating is over, the male rejoins the chorus with his typical "whee-ooh" calling song. Cicadas make their sounds with the help of a pair of sound-producing organs called tymbals. The tymbals are located on each side of the abdomen, right next to their ears. A tymbal is a tough yet flexible membrane that is supported by hardened ridges called ribs that are attached to a very powerful muscle. As the cicada contracts this muscle, the tymbal pops inward to create a sound. As the muscle relaxes the tymbal pops back into place and this also creates a sound. Rapid contractions and relaxations of the muscles for each tymbal results in the cicada's amazing song, which is further amplified by a large hollow area in the insects'' abdomen just under the tymbals. You would think that singing this loudly right next to your own ear would cause you to go deaf, but this doesn't happen because cicadas have special muscles that crease their ears while they are singing. It''s like wearing earplugs when working with power equipment. So there you have it: the secrets behind the 17-year Cicadas'' sudden springtime concert. Wil Hershberger is co-author, with Lang Elliott, of The Songs of Insects (Houghton Mifflin) -- a book about how singing insects do their thing that includes vivid photos of the bugs and an audio CD with their songs. A sample track appears here courtesy of the authors and publisher. Click Here To Hear The Otherworldly Song Of The 17-Year Cicada