Subclass II. PTERYGOTA 



Winged Insects 



The members of this subclass are winged; or, if without wings, they 

 have had winged ancestors and this is an acquired condition. The 

 mouthparts vary; in some they are sucking, in others chewing. The 

 metamorphosis varies from slight to gradual to complete. 



Much the greater number of species of insects belong to this 

 subclass and much the greater number of them possess wings, for 

 example, the beetles, flies, wasps, bees, and many others. Many 

 aphids, all fleas, lice, worker ants, female scale insects, and some 

 others have no wings. The wingless condition of these forms, how- 

 ever, is an acquired one, for the evidence is clear that they have de- 

 scended from winged ancestors. The subclass Pterygota contains all 

 of the remaining twenty -three orders discussed in this book. 



