138 



Hateful Grasshoppers, descending from the Rocky Mountains, will al- 

 ways continue to be the same or nearly the same. 



It may perhaps be thought, by those who have not carefully 

 studied the difference between the two cases, that, if the Colorado Po- 

 tato-bug could descend from the Eocky Mountains into Nebraska and 

 Iowa, and then pass onwards into Illinois, and so indefinitely for- 

 wards in its grand march to the Atlantic Ocean, the Hateful Grass- 

 hopper may do the very same thing. But the two cases are not 

 parallel. The Colorado Potato-bug, as we all of us in northern and 

 central Illinois know from woful experience, propagates freely and 

 rapidly, generation, after generation, in the northern lowlands of the 

 Mississippi Valley, and spreads by this means every year further and 

 further to the eastward; although it is very true that in the more 

 southerly lowlands of that Valley — such as Kansas, and Missouri and 

 South Illinois — it propagates much less freely and rapidly, and con- 

 sequently spreads but very slowly indeed towards the east. On the 

 other hand, superabundant evidence has been detailed in this chap- 

 ter, to prove that the Hateful Grasshopper does not breed anywhere 

 in the lowlands of the Mississippi Valley, but, on the contrary, gradu- 

 ally wastes away and disappears from off the face of the earth, when 

 raised there from the egg, without itself laying any eggs at all. 

 Therefore it is utterly improbable that this insect should, at any fu- 

 ture period, breed freely in the country immediately to the west of 

 the Mississippi, and thus pass gradually eastward into Illinois, and 

 after breeding there pass on still further eastward. And in point 

 of fact we know that the true Hateful Grasshopper has never been 

 found by any entomologists, even in very small numbers, from one 

 end of Illinois to the other. Moreover, the Colorado Potato-bug is a 

 slow-flying insect, physically unable to fly across the vast Plains of 

 the Western Desert at one fell swoop. Hence, until the distance be- 

 tween Colorado and eastern Kansas and jSTebraska was bridged by 

 settlements where potatoes were grown, it was incapable of passing 

 into Kansas and Nebraska, and thence through Iowa into Illinois; 

 and we know that history proves to us, so far as any negative fact 

 can be historically proved, that it never did so. On the other hand, 

 the Hateful Grasshopper is a rapid-flying insect, capable of flying 

 hundreds of miles at a stretch, when caught up by a strong westerly 

 wind; and there is historical evidence that it crossed the Plains, that 

 intervene between Colorado and the inhabitable or eastern parts of 

 Kansas, in 1820, or long before any white man had thrust his plow 

 into the virgin soil of those two districts. Therefore, if this Grass- 

 hopper is going at some future period to make its way into Illinois, 



