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Insects Fill Summer Skies with Music


More than 80 million people in the United States enjoy birding, according to the National Survey on Recreation and the Environment. Birders learn to recognize their favorite species by sight and by sound. Now, a new book and a companion CD aim to stimulate a similar public interest in another form of wildlife, insects.

On a warm summer evenings like we're experiencing right now in Washington, Americans can step into their backyards and hear the song of Allonemobius allardi, or Allard's ground cricket . It's one of 75 insect species featured in )

But Hershberger says, "With cicadas being so loud and such an important part of that acoustic environment of late summer and early fall, we thought we better include some."

Cicadas are the loudest singing insects in North America. The Songs of Insects features 13 species, including Linnaeus's 17-year Cicada (), which made an appearance this year in parts of the Midwestern U.S.

The author says 80 percent of the 75 different insects featured in the book are identifiable by their songs. The other 20 percent have songs that are very similar.

Only male insects sing and they don't sing like humans or birds. They don't have vocal chords.

Crickets and katydids use their wings. "On the bottom side of one wing is this line of teeth that looks like a file when you magnify it," Wil Hershberger explains. "And on the upper side of the other wing is a hard ridge that is called a scraper. As the male opens his wings, he lets the teeth pass over the top of that scraper, but when he closes, he drags the scraper across the teeth of the file. And it sets little membranes in the wings into motion, which creates sound."

Technically, they don't sing, they stridulate. Some grasshoppers and locusts drag their back legs over the edge of their wings to stridulate. Others don't stridulate at all; they crepitate, popping their wings taut. ()

Wil Hershberger says cicadas don't use their wings at all to sing. They use a tymbal. "It's a taut membrane that has several ribs to support it underneath, and attached to the ribs is this really strong muscle," he explains. "As the muscle contracts that tymbal pops in and when they release it, it pops back out. Contracting and relaxing that muscle very rapidly creates that popping sound. There is a hollow area under the tymbal that helps to amplify the song.

Hershberger says if we listen carefully to insects, they can tell us whether an ecosystem is in trouble. "If you go to a disturbed ecosystem and listen to the chorus, it sounds very different than if you go to a well-established park or wildlife management area that has been undisturbed for a very long time," he says. "If you look at a mature ecosystem, all of the species have partitioned the frequency spectrum so they aren't overlapping one another very much. In a disturbed ecosystem it is just a mess." ()

Wil Hershberger hopes The Songs of Insects will generate a new appreciation for the six-legged creatures and the unique music they create.

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