CHAPTER II. 

 STRUCTURE AND DEVELOPMENT OF INSECTS. 



The more experience the farmer has with insect pests, 

 the more he comes to realize that if he would successfully 

 combat them, he must have a certain amount of necessary 

 knowledge concerning their structure and growth. 



In general, the artificial means which may be effectually 

 used to combat an insect pest will very largely depend 

 upon the anatomical structure of the insect, while control 

 by general methods of cidture will depend upon a knowl- 

 edge of the peculiarities of its life-history. 



The value of a proper understanding of these important 

 factors in insect control is therefore apparent. 



General Structure of an Insect. 



The body of an insect is composed of three separate 

 parts, the head, thorax, and abdomen (Fig. 1), each of 

 which is composed of several rings or segments. To the 

 head are attached the jointed antennae, or feelers, the 

 compound eyes, and the mouth-parts, which are described 

 below. Each of the three segments of the thorax bears a 

 pair of legs, and adult insects usually possess one or two 

 pairs of wings upon the last two segments of the thorax. 

 The abdomen is composed of nine or ten segments, but 



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