Carrie Cochran, age 11, of Arlington Heights, I11., for her question:

HOW DOES A CRICKET CHIRP?

A cricket is an insect that is related to both the grasshopper and the katydid. Some are winged while others are wingless. Usually they are nocturnal.

Only the males produce the pleasant chirping sound. The song is made by elevating the front wings and rubbing the hardened portion, or 'scraper, of one wing against the ridged, filelike region of the other swing, causing vibration.

The rate of chirping and the pitch vary with the temperature of the air. Observers have worked out formulas for calculating temperatures from the number of chirps per minute.

Both sexes have hearing organs located in their front legs just below the knee. In China and Japan, people keep singing crickets in cages as pets.