Oak bush-cricket 'ear'

Insects do not have ears on their heads as mammals do, but the detection of vibrations and sound reception is very important to insects. By using a variety of organs many insects are able to detect a wide range of sound frequencies, far greater than our human ears can, the most elaborate of these organs is the tympanum.

A tympanum comprises of a section of flexible membrane, air sacs which evolved as modifications of the trachea and sensory cells. Several, quite distantly related insect group use this type of sensory organ suggesting that tympanal hearing has evolved independently on several different occasions. In bush crickets, tympanal organs are found on the foretibia, whereas in grasshoppers they are located on the hind legs, in some moth species tympana are found at the base of the wings.


For the species shown in the photo, Meconema thalassinum hearing is particularly important during courtship where males stridulate by tapping their hind tarsi on vegetation (this is fairly unusual for bush crickets, most rub their forewings together), this produces a very quiet drumming sound which attracts females.