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PHYSIOLOGY 



larval metamorphosis. The larva is very active and eats 

 voraciously, it molts again and again and then becomes 

 quiet. During the quiescent stage it eats nothing, for 

 important changes occur with which eating would in- 

 terfere. Through these changes the adult form is gained. 

 The insects are divided into nine classes. The well- 

 known forms that represent them are: (1) The silver 



Fig. 102.— Diagram of the anatomy of an insect, b, brain ; c, crop ; h, heart ; m, 

 Malpighian tubes ; r, reproductive organs ; s, stomach ; sg, salivary glands ; v, 

 ganglia of ventral chain. (From Kingsley.) 



fish, which eat paper and starched clothing; (2) Grass- 

 hoppers, crickets, locusts, which may damage crops 

 almost incalculably; (3) Dragon flies, may flies; (4) 

 Caddis flies and ant lions; (5) Flies, mosquitoes, pests 

 and carriers of disease; (6) Beetles, lady bugs, buffalo 

 bugs; (7) Ants, bees and wasps; (8) Seventeen-year 

 locust; (9) Moths and butterflies, whose larvae often 

 damage crops. 



