2o6 THE BIOLOGY OF INSECTS 



spike. She . . . remained perfectly still while the male 

 hovered a few inches above her head with a peculiar flutter 

 causing him to rise and fall a little." The male displayed 

 the " large, white brush-like structure . . . most energetic- 

 ally protruded and as rapidly withdrawn." But at length 

 " the female suddenly flew away as if the performance had 

 not appealed to her and the male followed." The reader 

 of this unfinished story may imagine, if he please, that the 

 courtship was finally successful. 



Besides vision and scent, there is reason to believe that 

 the females' power of hearing sounds produced by male 

 insects of a few groups is an important factor in courtship. 

 Reference has already been made (Chap. IV, pp. 80-82) to 

 the stridulating organs on the legs and wings of male grass- 

 hoppers and crickets which produce the familiar chirping 

 song of those insects, and the ears in the first abdominal 

 segment or near the front knee-joint with which they are 

 provided. It was also mentioned that some female crickets 

 from which the ears had been removed were no longer 

 attracted by the chirping of the males. Some positive 

 observations on the value of chirping and hearing in the 

 courtship of several species of European grasshoppers are 

 due to E. B. Poulton (1896). Some of the males appeared 

 to chirp in rivalry, and even to fight with each other by 

 means of kicking or biting. The power of stridulation 

 ** seemed almost without exception to be exercised with 

 direct reference to females, or in rivalry to other males in 

 the presence of a female." In a species Pezotettix pedestris 

 in which, the wings being underdeveloped in both sexes, 

 stridulation is impossible, the male practises nothing that 

 can be regarded as courtship, but jumps suddenly on a 

 female and captures her as his mate. It is likely, even 

 certain, that many insects produce sounds inaudible to us 

 but appreciated by the auditory organs of their own species, 

 and the perception of such excessively rapid vibrations 

 may be of service in courtship. For example, the beautifully 

 formed ear known as Johnson's organ in the base of the 

 feeler of many male gnats and midges may enable these 



