Class HEXAPODA 



The Insects 



The members of this class are air-breathing arthropods, with distinct 

 head, thorax, and abdomen. They have one pair of antennce, three pairs 

 of legs, and usually one or two pairs of wings in the adidt state. In 

 most adult insects the head bears a pair of compound eyes. The opening 

 of the reproductive organs is near the caudal end of the body. 



The more general character of insects, together with their structure 

 and morphology, has been discussed at some length in Part I of this 

 book. It is now appropriate to consider the classification, habits and 

 life histories of insects. Part II will therefore be devoted to a dis- 

 cussion of the subclasses, orders, and families of this great group of 

 animals. 



The class Hexapoda is divided into two subclasses, the small 

 wingless insects, Apterygota, and the winged insects, Pterygoia. 

 The subclass Apterygota is a small one, containing but three orders 

 (four by some authors) and mostly unfamiliar forms except to those 

 especially interested in these tiny creatures. The subclass Pterygota 

 is a very large group including all of the remaining twenty-three 

 orders discussed in this book. This subclass contains all of the more 

 familiar forms, such as grasshoppers, beetles, butterflies, moths, 

 flies, wasps, and bees. 



