2 ZOOLOGY 



feed upon almost any green part of plants. Some of tLu 

 species are gregarious (i.e. go in swarms) and may be 

 very destructive. 1 



Melanoplus 2 is the prevailing genus of North America 

 and covers nearly all of the continent. While in the 

 East certain species of the genus Melanoplus may become 

 destructive to vegetation, the injury done is not so great 

 as was formerly done by the Rocky Mountain locust. At 

 various times for some cause, probably drought, this locust 

 has migrated eastward from its mountain home in countless 

 millions and devastated our Western States as far as the 

 Mississippi River. In 1873 to 1877 the Rocky Mountain 

 locust was so destructive to vegetation in the trans- 

 Mississippi region that Congress appointed a commission 

 to investigate the species. In describing its effect the 

 commission reports : - 



" Falling upon a cornfield, the insects convert in a few hours the 

 green and promising acres into a desolate stretch of bare, spindling 



1 The following key will aid in determining the four principal Ameri- 

 can subfamilies of the Acrididse : 



a\. Feet without a claw-pad. Pronotum covering all 



the body. Fore wings lobe-like .... Tettigidce 



(Tettix Shorthorns) 



a*. Feet with a claw-pad ; antennse longer than an- 

 terior femora. 

 61. Prosternum without a spine. 



GI. The plane of the vertex of the head meet- 

 ing the plane of the front of head at an 

 angle, the face looking down . . . Tryxalidce 



(Angle-headed Shorthorns) 



C2. The planes of the vertex and head round 



over into each other .... CEdipodce 



62- Prosternum with prominent spine . . . Mehtnoplidce 



(Thorn-throated Shorthorns) 



s, black ; oir\a, armor. 



