Forest Preserve District of Cook County, Illinois
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The Insect Orchestra
Nature Bulletin No. 723   September 14, 1963
Forest Preserve District of Cook County
Seymour Simon, President
David H. Thompson, Senior Naturalist

THE INSECT ORCHESTRA
Insects furnish background music for summer and early autumn. They chirp, buzz, hum or squeak in monotonous rhythms, each in his own way, some in bright sunlight and others at night. All are instrumentalists, not vocalists, and almost all are males playing solos.

Although the great majority of insects are silent, the crickets and katydids that we hear today have ancestors that were among the world's oldest soundmakers. They tuned up first back in the Age of Reptiles, 200 million years ago, long before there were birds to sing or mammals with voice boxes.

Crickets are easily the most popular of these insect musicians and our Black Field Cricket is a star performer. His usual song is a shrill "treet-treet-treet" so high-pitched that many people cannot hear it. He also strums a low "gru-gru-gru. These sounds are made by rubbing the two front wings together. A scraper on the right wing is rapidly pulled back and forth over a heavy rib with fine file-like teeth on the left wing -- much like flipping the teeth of a comb with your thumbnail. n is hard to tell whether a chirping male is courting a female, challenging other males, or just fiddling for the fun of it. Both sexes have ears -- seen as a tiny spot on each foreleg just below the "knee".

Crickets thrive and sing when kept in a tall glass jar with a piece of sod in the bottom, and fed bits of bread. The life span of the adults is about a month and the male spends a large part of his month chirping. He sometimes sings along with a musical instrument and has been known to answer another male over the phone.

Although seldom seen where he hides among the foliage, the Snowy Tree Cricket produces a continuous succession of weird throbs of sound that seem to come from all directions. From sundown until sunrise, he saws away on a single note -- faster on hot nights and slower on cool ones. Hence, he is also called the Temperature Cricket because it has been found that he is as accurate as most home thermometers. Count the number of chirps in fifteen seconds and add 39 to get the temperature in degrees Fahrenheit.

During the first nights of August the Katydid starts his harsh rasping calls from high in trees and shrubs. They are large green slab-sided insects with leaf-like wings -- so well camouflaged that they are practically invisible. They are kin to the crickets and, like them, the males fiddle with their front wings. On warm evenings, with the temperature above 75, he sings a loud "Kay-Tee-Did-It" with each syllable stressed. As the night cools, he slows down and drops one syllable after another until, when it falls below 60, he merely mumbles a hoarse "Kate".

Of all the daytime singers the Cicadas are the noisiest. Their curious sound-making apparatus consists of a pair of membranes or drums on the underside of the abdomen. But, instead of by drumsticks, these are vibrated by a pair of powerful muscles. In late summer the ones called the Harvest Flies, after two or three years of underground life, come out into the open and transform into flying adults. These move into the tree tops where the males make a rattling tattoo that tapers off like an alarm clock running down.

The next mass appearance of the Periodical Cicada or "Seventeen Year Locust" in the Chicago region is due in June, 1973. Individually, a male yells "o-o-o-E-E-E-yow". Multiplied by countless millions during the daylight hours, they create a fearsome din in our forest preserves.


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