CHAPTER XXI 



BRANCH ARTHROPODA (continued}; CLASS IN- 

 SECTA: THE INSECTS 



THE LOCUST (Melanoplus sp.) 



TECHNICAL NOTE. Locusts or grasshoppers are common and 

 familiar insects all over the country. The genus Melanoplus in- 

 cludes numerous species, one or more of which are to be found in 

 almost any locality. The common red-legged locust (M. femur- 

 rubruni} of the East, the Rocky Mountain migratory locust (M. 

 spretits], of the West, the large differential (M. differentialis} and 

 two-striped (M. bivittatus} locusts of the Southwest, are especially 

 common species. All the members of the genus have their hind 

 wings uncolored, and the front wings marked with a longitudinal 

 series of small dots more or less distinct, or with a longitudinal line. 

 There is a small blunt spine or process projecting from the ventral 

 aspect of the prothorax. If a species of Melanoplus cannot be 

 found, any other locust may be used, although there are some slight 

 variations in the external structure of the various species. Fresh 

 specimens killed in a cyanide bottle (for preparing see p. 463) are 

 preferable in the study of the external structure, but specimens 

 preserved in alcohol will do. 



External structure (fig. 38). Note that the body of 

 the grass-hopper is composed of successive rings or seg- 

 ments grouped into thre^ regions, the head (anterior), 

 thorax (median), and abdomen (posterior). In which 

 region of the body are the segments most readily distin- 

 guished ? Of how maji}t-srgmeris <-i oes the head appear 

 to be composed ? The thorax is composed of three 

 segments of which the most anterior, to which is attached 

 the front pair of legs, differs from the succeeding two, 

 being freely movable and bearing a large hood- or saddle- 

 shaped piece on its dorsal aspect. To the other two 

 thoracic segments the second and third pair of legs are 



157 



