Norris R. Brown, age 14, of Timmonsville, South Carolina, for his question:
A certain fly constantly buzzed a true F note above middle C. He led a captive life in a lab while scientists studied his behavior. They were used to his happy humming. But one cool day, his usual F note was miserably flat. Then someone turned up the heat and the busy buzzer buzzed on key again. The multitude of sounds made by flies, crickets and countless other insect musicians are indeed affected by temperature, and also by several other factors.
The insects are nature's top jazz musicians. Some of this wild orchestration begins at sundown and lasts until dawn. From early spring to late in the fall, every night is a jam session. There are drummers and fiddlers and dozens of other special¬ists, each with its own built in instrument. The various crickets are master fiddlers. The ground cricket plays double beat bass notes. The tree dwelling crickets use fancy vibrating and amplifying tricks to create high pitched trills up and down the scale. The shrill katydids, the drumming cicadas and dozens of other specialists play in other sections of the band. But the crickets are outstanding, perhaps they are so numerous.
All these jazzy insects play by moving parts of their bodies to make air molecules vibrate in fast motion. This, of course, is the normal way to produce sounds of any sort. To make these motions the insect musicians must use energy. And insects are cold blooded animals who depend for their warmth upon their surroundings. A warm bug is peppier than a cold bug. The quality of pitch depends upon the number of sound vibrations per second. Faster vibrations produce higher notes.
On a cool evening, the sluggish crickets drag their saw edged bows more slowly back and forth. This creates fewer vibrations per second, lower frequencies and lower notes. But on a hot sultry evening, they feel warm and peppy. They scrape faster and their notes rise higher. In the same way, changing temperatures affect the pitch of all the other musicians in the insect orchestra. During the performance, the average cricket also does a lot of scuttle around. As he hops through his grassy world, his surroundings change and this too may vary the pitch of his chirping.
Other factors also affect the pitch of a cricket's notes. Like everybody else, he sometimes gets tired. When fatigues, his notes are lower because his bowing slower. Sometimes he gets excited. When playing a love song to an irresistible lady cricket, he scrapes his wings fast with all his might and his "Creek Creek" double beat rises higher and higher. Insect notes also are affected by the behavior of sound waves passing through the air. When breezes stir the grassy meadows, sound vibrations may be crowded together. Then we hear the tangled threads of sound as a bewildering tangle of off beat notes.
Rocks and other formations may amplify or enlarge the sounds of insects. But many insects do not depend upon such outside assistance. They have their own built in amplification systems. Perhaps the master of this art is the katydid, a cousin of the cricket. Normally he fiddles a shrill, double beat "Zeep Zeep." When tired, he merely whispers. But when warm and peppy, the membranes of his amplification system speed up and that whisper can be heard almost a mile away.