JANX^ART. 13 



ral check. Nature has so organized these birds that they can 

 subsist on these insects, and upon nothing else in the world. 

 The swallows attack them in their native element, and there- 

 by render a service to man, which could be performed by no 

 other known agency. 



Secondly, there are other tribes of insects, as minute as 

 those just described, that do not swarm in the atmosphere, 

 but live on the surface of trees and other plants, feeding upon 

 their leaves, fruit and substance, and capable, if their increase 

 be not checked, of destroying all the labors of the husband- 

 man, and interrupting the whole progress of vegetation. In 

 this category may be reckoned the sand-flies, the smaller 

 tribes of beetles, ticks and red-bugs, and countless myriads of 

 plant-lice, whose power of doing mischief is in direct ratio to 

 their minuteness. The natural checks to the over-multipli- 

 cation of these crawling insects are the common sparrows, 

 the wrens and small fly-catchers, all the Sylvias, or true 

 warblers, and most of the small birds. 



Thirdly, we observe many species of large insects, includ- 

 ing butterflies, grasshoppers, crickets, locusts, and the larger 

 beetles. The smaller birds are unequal to the task of attack- 

 ing and devouring these large insects. The natural checks 

 to their increase are the thrushes, including the common 

 robins, the orioles, the large fly-catchers, jays, and crows. 

 The insects, for the most part, devoured by these birds, are 

 mischievous, both while they are grubs, and after they have 

 become perfect insects. In their perfect state they consume 

 the leaves, and in their larva state the roots, the fruits, and 

 the wood and inner bark of trees, and vegetables. 



Fourthly, there are certain species of insects whose larvas 

 find their subsistence by boring into the wood of certain trees, 

 where they are beyond the reach of nearly every species of 

 birds. Such are the borers that ravage our fruit trees, and 

 often destroy great portions of the forest. The birds that 

 prey upon these insects must be furnished with a hard beak 

 and a strong neck, besides a peculiar instinct to enable them 

 to discover their lurking place. Such are the woodpeckers, 

 which have the faculty of drawing out these vermin from 



