LETTER OF TRANSMITTAL 



U. S. DEPARTMENT OF AGRICULTURE, 



BIOLOGICAL SURVEY, 



Washington, D. C., December 23, 1910. 



SIR: I have the honor to transmit herewith for publication as 

 Bulletin No. 37 of the Biological Survey, a report on the Food of the 

 Woodpeckers of the United States, by F. E. L. Beal, assistant, Bio- 

 logical Survey. The diminished supply of timber and its greatly 

 increased cost render the conservation of our remaining forests 

 exceedingly important. It has been estimated that within the 

 United States insects destroy trees and lumber to the value of upward 

 of $100,000,000' annually. As boring insects are the natural enemies 

 of trees, so birds are their natural allies. Of all birds that further the 

 welfare of the forest, woodpeckers are the most important, many of 

 them indeed being specially adapted to dig into wood in order to 

 reach insect larvae safe from all other enemies. While most wood- 

 peckers are thus highly beneficial, the sapsuckers are injurious, since 

 they subsist to a considerable extent on the cambium or inner bark 

 of trees. This bulletin is meant to serve a practical end by describ- 

 ing the food habits of the several species, and by pointing out the 

 extent to which each is beneficial or injurious, so that the forester, 

 the farmer, and the orchardist may know friend from foe. 

 Respectfully, 



H. W. HENSHAW, 

 Chief, Biological Survey. 

 Hon. JAMES WILSON, 



Secretary of Agriculture. 



