136 Cockroaches, Locusts, Grasshoppers, and Crickets 



The life-history of all our locusts is, in general characteristics, very similar. 

 The eggs are deposited in oval or bean-shaped packets enclosed in a glutin- 

 ous substance. They are usually laid just below the surface of the soil, 

 but in some cases are simply pushed to the ground among the stems of 

 grasses, while a few locust-species thrust them into soft wood. The strong, 

 horny ovipositor at the tip of the abdomen is worked into the ground, the 

 four pieces separated, and the eggs and covering mucous material extruded. 

 The eggs in a single mass number from twenty-five to one hundred and 

 twenty-five, varying with different species, and the females of some species 

 lay several masses. The different species also select different times and 

 places for egg-laying, some ovipositing in the fall and some in the spring, 

 while some select hard, gravelly, or sandy spots or well-traveled roads, and 

 others choose pastures and meadows and the uncultivated margins of irriga- 

 tion-ditches. 



If the eggs are laid in the fall, the more usual case, they do not hatch 

 until the following spring. The young hoppers are of course wingless, very 

 small, and pale-colored, but they have the general body make-up of their 

 parents, with the biting mouth and long-leaping hind legs. They push 

 their way above ground and feed, as do the adults, on the green foliage of 

 grasses, herbs, or trees, and in two or three months become full grown and 

 mature, having moulted five or six times during this growth and developed 

 wings. The wings begin to appear as minute scale-like projections from 

 the posterior margins of the back of the meso- and meta-thoracic segments, 

 and with each moulting are notably larger and more wing-like in appear- 

 ance. During all this development the wing-pads are so rotated that the 

 hinder wings (always underneath the fore wings in the adult locust) lie out- 

 side of and above the fore wings (Fig. 156). 



The family Acridiidae includes in the United States about 500 species, 

 representing 107 genera. These genera are grouped in four subfamilies 

 as follows: 



KEY TO SUBFAMILIES OF ACRIDIID^E. 



Pronotum (dorsal wall of prothorax) extending back over the abdomen nearly or quite 

 to its tip; tegmina (fore wings) short and scale-like .............. TETTIGIN^E. 



Pronotum not extending back over abdomen or only slightly; tegmina usually well 



developed (sometimes short or wanting). 



Prosternum (ventral aspect of prothorax) with a prominent thick conical or cylindrical 

 spine ......................................................... ACRIDIIN.E. 



Prosternum not spined (sometimes a short, oblique, inconspicuous, obtuse tubercle). 

 Face very oblique .............................................. TRYXALIN^E. 



Face nearly or quite vertical 



In the subfamily Acridiinae the most conspicuous and economically 

 important member is the Rocky Mountain or hateful migratory locust, 



