THEIR RELATION TO PLANTS 55 



their eggs in little masses in holes in the ground, which 

 they bore with the homy valves at the end of the 

 body, and they select moderately firm, dry ground for 

 that purpose. Much moisture is dangerous or even 

 fatal to the eggs, hence it is in desert or semi-arid 

 countries that they are most abundant. Such condi- 

 tions in our country exist among the foot-hills of the 

 Rocky Mountains and no place that I have ever seen 

 exceeds that region in the variety and abundance of 

 its grasshoppers in a normal season. Sometimes, 

 when conditions become unusually favorable, grass- 



FlG. 17. — The American grasshopper or locust, Schistoccrca americana. 



hoppers may become so very abundant that the vege- 

 tation in their native locality is insufficient to support 

 them, and then some species better fitted for flight 

 than others, take wing and seek new feeding grounds. 

 Some are unable to get very far, and rest as close to 

 home as they can, starving if they get beyond the limits 

 of their strength without discovering new pastures; 

 but other, longer winged species, accomplish hundreds 

 of miles from the Rocky Mountains to the Mississippi 

 Valley, alighting first where cultivated lands begin. 

 Thus Kansas, Nebraska and the Dakotas were pre- 

 eminently sufferers from grasshopper invasions, and 

 not infrequently conditions were sufficiently good 

 there to permit the insects to lay their eggs, providing 

 for a brood which the year following destroyed the 



