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 Xo. 39 of the Biological Survey, a report on Woodpeckers in 
Relation 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 larva? 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 hi the United States amounts yearly to not less 
than 81,200,000. Tins 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, Hexry W. Hexshaw. 
Chief, Biological Survey. 
Hon. James Wilsox, 
Secretary of Agriculture. 
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