CHAPTER II. 



THE EXTERNAL ANATOMY OF A LOCUST. 

 (Mela?iophis femur-rubrum. ) 



Locusts or short-horned grasshoppers are excellent 

 subjects to use in beginning the study of the external an- 

 atomy of insects. They are very common and are compara- 

 tively large ; and the parts of the external skeleton in these 

 insects are, as a rule, remarkably distinct. 



The species which has been selected as the basis of this 

 outline is the red-legged locust, Melanoplus femur-rubrum^ 

 which is found in nearly all parts of the United States. 

 Specimens of this insect, preserved in alcohol, will be fur- 

 nished the student, who will be expected to verify carefully 

 or to correct each statement made in the text. 



DIVISION OF THE BODY INTO REGIONS. 



The body of a locust is composed of a series of more or 

 less ring-like segments. In the caudal part of the body the 

 ring-like nature of the segments is obvious ; in the cephalic 

 part it is less so. These segments are grouped into three 

 regions : head, thorax , and abdomen. 



Head. — The head is the first or cephalic of the three 

 regions of the body. Apparently it consists of a single seg- 

 ment. 



Thorax. — The thorax is the second or intermediate region 

 of the body. It is readily distinguished by its appendages ; 

 which are three pairs of legs and two pairs of wings. It 

 consists of three segments ; but as each segment is composed 

 of several distinct pieces, it requires considerable study to 



