THE SPECIAL SK.\SF:S 



sound. The antennas may be considered, then, to have 

 within them three classes of nerves: nerves of touch, 

 of smell, and of hearing. 



Production of Sound. Insects have no true voice. We 

 are all familiar with the shrill cry of the cicada or 

 harvest-fly, the song of the katydid, and the chirp of 

 the cricket. These are no doubt calls to other individ- 

 uals of the same species. The cicada produces its pierc- 

 ing notes from a pair of membranes on the under side of 

 flic base of the abdomen of the male. The membranes 

 cover depressions and vibrate rapidly somewhat like 

 two kettle-drums. It is only the male that possesses 

 the-e organs. This has led some one to say in rhyme: 



" Happy the cicadas' lives, 

 For all have voiceless wives." 



The student, with the male 

 cicada in hand, will not have to 

 wait long before he is permitted 

 to hear and observe these sound- 

 producing membranes in action. 

 The katydid brings forth its'song 

 hy rubbing its fore wings upon 

 each other. (Fig. 31.) The 

 male cricket will not usually re- 

 main long under a glass tumbler 

 before he begins rubbing the base 

 of his upper wings on the base of 

 his under wings ( Fig. 32), pro- 

 ducing that familiar clicking 

 sound. Certain moths and but- 



Fir,. 32. Wing-cover of male 

 cricket, showing sound-pro- 

 ducing apparatus. Each wing- 

 cover is equipped with our oi 

 these flies, r, enlarged at a, 

 and a scraper. When the 

 cricket wishes to call, he.ele- 

 \ates his wings so that the 

 scraper of each wing rasps mi 

 the tile of the other, when the 

 wings are moved sidewise. 

 This sets the membranous 

 wing-covers in vibration and 

 produces the characteristic 

 chirp of the cricket. 



