Teachers' Leaflet. 459 



In handling the grasshoppers, notice that they have two ways of 

 preserving themselves; first, by jumping; second, by spitting a dark- 

 colored, disagreeable, acrid fluid upon the enemy. 



LESSON XIV. 



THE GROWTH OF GRASSHOPPERS AND CRICKETS. 



Purpose. — To teach that some insects look practically the same from 

 the time they hatch until they are fully grown, and have no quiet stage, 

 as the pupa of the moth or butterfly. 



Observations to be made. — The small crickets look like the old 

 crickets and young grasshoppers look like old grasshoppers, except in 

 the young ones the wings are not yet developed, so they could not fly 

 if they wished to. In the very small ones, the wings are little pa,ds ; 

 later they show as wings, but they are wrongside up and the wings are 

 outside instead of beneath the wing covers (see " Comstock's Manual," 

 p. 51). This is the place to study the differences between the wing covers 

 and the wings ; the wing covers in the adults are hard and stiff and are 

 held rigid in an upright position when the insects fly ; the wings are 

 folded like a fan beneath these covers when not in use. 



LESSON XV. 



HOW THE CRICKETS MAKE MUSIC. 



Purpose. — To teach that the songs of insects are for the pleasure of 

 other insects. 



Only the father crickets have musical instruments on their wings; 

 this music is not only used to attract to them their sweethearts, but also 

 it is kept up steadily long after the time of marriage just for the joy of it. 

 The children should observe that the mother crickets, which have the 

 long, sword-like organ at the end of the body never make any music. 

 They should also notice the differences in the wing covers between the 

 father and the mother crickets, the wing cover of the father cricket 

 being a membrane stretched over a frame, which may be compared to 

 the body part of a violin or mandolin. They should notice the way the 

 cricket moves his wings when he chirps. After the chirping has been 

 observed the teacher should give a demonstration either from a wing of 

 a cricket under a microscope, or a picture in a book, or a blackboard 

 drawing showing the file and the scraper (" Comstock's Manual." p. 118). 

 In explaining the mechanism of the music compare the file to the strings 

 and the scraper to the pick, and the wing to the body of a mandolin. 



