ADAPTATION FOR THE SPECIES 135 



while the grasshopper has his ears upon the side of 

 his body. 



Everyone who lives in the country, or goes into the 

 country in the summertime, is sure to know the hum- 

 ming of the so-called locust. It is an unfortunate fact 

 that the word locust may have several meanings. It 

 is properly applied to one group of the grasshoppers. 

 The creature most commonly called a locust is a 

 cicada, or harvest fly. When the weather gets quite 

 warm the cicada starts his love song. He has two 

 long flaps to his vest, and under each flap he has a 

 vibrating drum head. This is set shivering by a mus- 

 cle on its under side. The female cicada again is 

 silent. 



It is among birds that the love song reaches its 

 finest development. It may consist simply of a little 

 chirp as in the chippy. It may consist of two notes 

 of a different pitch repeated steadily, as in the tufted 

 titmouse. It may attain considerable variation, as in 

 the robin. But in the choir of our best singers, like 

 the catbird, thrasher, and mocking bird, there is un- 

 ending variation of notes. It seems almost impossible 

 to doubt the charming quality of this voice upon the 

 mate. It certainly is chiefly confined to the mating 

 season, and is indulged in almost entirely by the 

 males. This does not mean that a male does not sing 

 excepting when he wishes to charm his mate. But 



