i8 



PRACTICAL ZOOLOGY 



trols the swallowing movements, regulates digestion and breath- 

 ing, and controls the salivary glands and circulation. 



Reproduction. -- Grasshoppers do not live very long and the 

 race must therefore be continued from year to year by the pro- 

 duction of new individuals. The processes involved are those 

 connected with the formation of eggs and the development of 

 the eggs and young until the adult stage is reached. The 

 eggs, or female germ cells, arise within the egg tubes of the 

 female insects. Before they are laid they are penetrated by the 



FIG. 5. Rocky Mountain locusts laying eggs. (After Riley.) 



male germ cells which arise in the reproductive organs of the 

 male (Fig. 3, tes); this union of male and female germ cells is 

 known as fertilization. During July and August these eggs 

 are formed into masses of from thirty to one hundred, covered 

 with a sort of jelly, and deposited in a hole in the ground about 

 an inch below the surface (Fig. 5). Here they remain through- 

 out the winter. The following spring the young emerge from 

 the egg in a form resembling their parents in many ways, but 

 differing from them in the size of the head and absence of wings 

 (Fig. 6). As the young grow, the exoskeleton becomes too tight 

 for them, so they shed it (molt) at intervals and acquire a new 



