U. S. DEPARTMENT OF AGRICULTURE 
BIOLOGICAL SURVEY 
WASHINGTON, D. C. 
C. HART MERRIAM, CHIEF 
T. S. PALMER, Assistant Chief 
January 4, 1901. 
Mr. William Brewster 
Bethel, Maine. 
My dear Brewster: 
Prof. A. D. Hopkins of Morgantown, W. Va., has Been engaged 
for some time past in making a special study of the relation of 
insects to forests. In June last he visited the woods of Maine 
for this purpose and did a lot of work in the Androscoggin region 
north of the Mangeley Lakes. He formerly Believed (and published 
this belief) that in forest areas birds do mere harm than good by 
destroying beneficial insects which live or pupate in the bark.of 
trees. But during his present investigation, he has been over¬ 
whelmingly convinced of the error of his former position and now 
believes that woodpeckers are the most important factor in the 
pres- rvation of forests. 
The destructive spruce beetle in particular is held in check 
by woodpeckers. He has just prepared a bulletin which will be 
published almost immediately on this subject, and has come to me 
to find out what woodpeckers occur in the Rangeley Lakes region 
and at what seasons the several species feed most extensively on 
tree trunk larvae. I told him that the hairy, downy, and three¬ 
toed woodpeckers were doubtless the ones which do most of the work. 
He thinks that particularly important work is done in winter, pro¬ 
bably by the three-toed species. He has found evidences of their 
work in all the infested districts and has been deeply impressed 
