PROTECTIVE DEVICES 



57 



almost exclusively upon the sandy and dusty ground, 

 are dust-colored, while other grasshoppers, that live in 

 the grass exclusively, are of a greenish color? Not 

 only are they greenish in color, hut in the case of a 

 certain green grasshopper which spends much of its 

 time upon the lamb's-quarter, there are marks of red 

 corresponding to the red markings upon the green 

 lamb's-quarter, showing further resemblance to sur- 

 roundings. These colors have not been assumed as a 



O 



matter of choice by the insects, just as we choose the 

 colors of the clothing we wear, but have arisen through 

 slow and gradual development. Is it not evident that 

 the green grasshoppers upon the dusty road would be 

 very conspicuous objects for birds and other enemies ? 

 If perchance a few should he somewhat gray or dusty 

 in color they would be more likely to escape the notice 

 of enemies, and naturally would tend to reproduce others 

 of like color. Thus the matter of color not only becomes 

 firmly fixed but most decidedly pronounced. And the 

 same might be said about the dust-colored insects among 

 the green grass. 



"The world is made up,'" says Scudder, "of eaters 

 and eaten, of devices to catch and devices to avoid being 

 caught." So, whenever we find very large numbers of 

 one species of insect life prevalent we will do well to 

 look about to see if we can ascertain what trait of char- 

 acter or propitious conditions have furnished this group 

 sufficient protection to enable the individuals to increase 

 in such numbers. 



Mimicry. A feature of greatest interest among adult 

 insects, and, we may say, one of the most successful in 

 its purpose, is that means of defense which is secured 



