Aug. 27, 1999

     Singing Insects

When I spend August nights away from home in an air-conditioned room, I miss the insect chorus we enjoy through our open windows in the countryside.  Late summer nights are best.  The insect population is at its height and most of the individuals have reached their maturity, so by 8 p.m. the activity of the night insects is in full swing.  One can locate these nighttime singing insects by carefully searching with a flashlight.  A beam swinging downward into the lawn might reveal musicians such as the black field crickets with their chirping sounds.

A black field cricket sings with his wings.  Although a cricket has two pair of wings, the front or upper wings are the sound makers.  There are tiny ridges, like the ridges of a file, on the underside of these wings.  There is also another thickened area, like a scraper, on the edge of the wings.  The cricket moves his wings rapidly from side to side, rubbing them across each other so they vibrate and make a rasping noise, the "chirp."

Female crickets don't sing, but they listen with eardrums near their knees.  Other types of crickets, plus katydids and cone-headed grasshoppers, make their special music by rubbing wing parts.

Why do crickets, grasshoppers and katydids sing?  Biologists have found they have one song to attract females and another to ward off rivals.  They also seem to enjoy the sound of their own "voices."  Their chorus is a remarkable part of a summer night in Minnesota.