ELEMENTARY STUDIES IN INSECT LIFE 



FIG. 30. Front leg 

 of cricket, showing 

 ear-like organ (a). 



ing. This cover corresponds in its use 

 to the tympanum of our own car. On 

 the internal surface of this tympanum 

 there are two horn-like processes, and at- 

 tached to these is a very delicate little 

 sac filled with a transparent fluid. This 

 sac represents the membranous laby- 

 rinth, and is connected with the auditory 

 nerve, which goes to the brain. This 

 tympanal 

 structure 



is to be found in the 

 common black .cricket, fa- 

 miliar katydid, and their 

 allies, on the inside of the 

 tibia of the front leg. The 

 organs of hearing have 

 different locations in dif- 

 ferent insects. It has been 

 demonstrated that the an- 

 tenna 1 of the male mosquito 

 vibrate to the sound-wave 

 of the tuning-fork. It is 

 quite probable that a num- 

 ber of other insects per- 

 ceive sounds through 

 nerves which terminate 

 exteriorly in the antenna 1 . 

 The functions of the an- 

 tennal nerves of insects 

 are varied, capable of per- 

 ceiving contact, odor, and 



FIG. 31. Wing-covers of male katydid, 

 The one on left shows heavy file-like 

 structure on under side near base (en- 

 larged just above wing); the one on right 

 shows membranous structure near base 

 with pointed ridge on upper side (en- 

 larged just above wing), extending out- 

 ward. The right wing is passed under 

 the left wing, the sharp ridge rasps upon 

 the file of the left wing, the membrane 

 of the left wing vibrates, producing the 

 " song " of the katydid. 



