LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Biological Survey, 



Washington, D. C, May 24, 1911. 

 Sir: I have the honor to transmit herewith, for publication as 

 Bulletin No. 39 of the Biological Survey, a report on Woodpeckers in 

 Kelation to Trees and Wood Products, by W. L. McAtee, assistant, 

 Biological Survey. Woodpeckers as a family take high rank among 

 our insectivorous birds, and being specially equipped to dig into 

 wood for hidden larvae inaccessible to other birds aid materially in 

 the conservation of our forests. Three members of the group, how- 

 ever, the only ones properly known as sapsuckers, are injurious, 

 since their chief purpose in digging into trees is to secure the cambium 

 and the sap for food. The holes they make also permit entrance of 

 moisture, bacteria, and fungi which injure and sometimes destroy 

 the tree. They also cause staining of the wood, seriously impairing its 

 market value when converted into lumber. Altogether the damage 

 done by sapsuckers in the United States amounts yearly to not less 

 than SI, 200,000. This bulletin treats of the more strictly economic 

 aspects of woodpecker work, and points out wherein the birds are 

 beneficial and wherein injurious, and in the latter case suggests 

 remedies. 



Respectfully, Henry W. Henshaw, 



Chief, Biological Survey. 

 Hon. James Wilson, 



Secretary of Agriculture. 



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