CHAPTER II. 



THE EXTERNAL ANATOMY OF A LOCUST. 



(Mdanoplus femur -rubrurti.) 



Locusts or short-horned grasshoppers are excellent 

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

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

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

 insects are mostly 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. 



In order to illustrate certain points not well shown in the 

 locust, comparative studies will be made of parts of a cock- 

 roach. 



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. 



