FACTS THAT PROVE THE UTILITY OF BIRDS. 257 



duced no fruit. It is only by such unfortunate experi- 

 ence that men can learn that the principal value of birds 

 does not consist alone in their flesh or in their power of 

 conferring pleasure by their songs. 



Some years ago, in Virginia and North Carolina, several 

 tracts of forest were attacked by a malady that caused 

 the trees to perish over hundreds of acres. A traveller 

 passing through that region inquired of a countryman if 

 he knew the cause of the devastation. He replied that the 

 mischief was all done by the woodpeckers, and though 

 the inliabitants had killed great numbers of tliem, there 

 still remained enough to bore into the trees and destroy 

 them. The traveller, not satisfied witli this account, 

 made some investigations, and soon convinced them that 

 the cause of the mischief was the larva of a species of 

 Buprestis, which had multiplied without limits. Tliis 

 larva w^as the favorite food of the woodpeckers, which had 

 congregated in that region lately on account of its abun- 

 dance. He showed them that they were protecting the 

 real destroyers of the forest by warring against the 

 w^oodpeckers, which, if left unmolested, would soon eradi- 

 cate the pest sufficiently to save the remaining timber. 

 Birds become accustomed to certain localities, and if by 

 any accident they should be exterminated in any one 

 region insects of all kinds will increase, until the birds 

 that consume them are slowly attracted to them from 

 otlier parts. 



In the year 1798, in the forests of Saxony and Bran- 

 denburg, the greater part of the trees, especially the coni- 

 fers, died, as if struck at the roots by some secret malady. 

 The foliage had not been attacked, and the trees perished 

 without any manifest external cause. The Eegency of 

 Saxony sent naturalists and foresters to investigate the 

 conditions. They proved the malady to be caused by the 

 multiplication of a species of lepidopterous insects, which 



