196 



NATURAL HISTORY OF ARTHROPODS. 



air sacs, all these traits conspire to make it the terrible engine of destruction 

 which history shows it to have been under conditions favorable to its excessive multi- 

 plication. Insignificant individually, but mighty collectively, locusts fall upon a 

 country like a plague or a blight. The farmer ploughs and plants. He cultivates in 

 hope, watching his growing grain, in graceful, wave-like motion wafted to and fro by 

 the warm summer winds. The green begins to golden ; the harvest is at hand. Joy 

 lightens his labor as the fruit of past toil is about to be realized. The day breaks with 

 a smiling sun, that sends his ripening rays through laden orchards and promising fields. 

 Kine and stock, of every sort, are sleek with plenty, and all the earth seems glad. 

 The day grows. Suddenly the sun's face is darkened, and clouds obscure the sky. 

 The joy of the morn gives way to ominous fear. The day closes, and ravenous locust- 



FIG. 273. Pachytylus migraforius (on the right variety P. cinerascens), old world locust. 



swarms have fallen upon the land. The morrow comes, and, ah ! what a change it 

 brings ! The fertile land of promise and plenty has become a desolate waste, and old 

 Sol, even at his brightest, shines sadly through an atmosphere alive with myriads of 

 glittering insects 



" Falling upon a cornfield, the insects convert in a few hours the green and prom- 

 ising acres into a desolate stretch of bare, spindling stalks and stubs. Covering each 

 hill by hundreds ; scrambling from row to row like a lot of young, famished pigs, let 

 out to their trough; they sweep clean a field quicker than would a whole herd of 

 hungry steers. Imagine hundreds of square miles covered with such a ravenous horde, 

 and one can get some realization of the picture presented in many parts of the counti'y 

 west of the Mississippi during years of locust invasion. 



"Their flight may be likened to an immense snow-storm, extending from the 

 ground to a height at which our visual organs perceive them only as minute, 



