136 Cockroaches, Locusts, Grasshoppers, and Crickets 



The lifc-hi.story 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 Ijclow 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 

 [)laces 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 liody 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 

 gras.ses, herbs, or trees, and in two or three months become full grown and 

 mature, having moulted five or si.x 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 .\cridiid;c includes in the United States about 500 species, 

 representing 107 genera. These genera are grouped in four subfamilies 

 as follows: 



KEY TO SUBF.\MILIES OF ACRIDIID^. 



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



to its lip; tegmina (fore wings) short and scale-like Tetticix.i;. 



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

 developed (sometimes short or wanting). 

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



spine AcRiDiiN.E. 



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



Face ver)' oblique Tryxalin.c. 



Face nearly or quite vertical CEDIPODIN.1E. 



In the subfamily Acridiinae the most conspicuous and economically 

 important member is the Rocky Mountain or hateful migratorv locust, 



