54 WOODPBCKEBS IN RELATION TO TREKS. 
Bpecies in the United States, of which 248 are known to be punctured 
l>\ sapsuckers. Thirty-eighl introduced species are at lacked, which 
belong to 17 families, 3 of which have no native representatives. 
Sixty-three of the total number of trees and shrubs are seriously 
damaged by sapsuckers and 31 of them, besides 1 vine, are known to 
be killed. There are 31 families of plants having native arborescent 
species in t his country, and 7 wholly introduced families, no member of 
which is known to be attacked by sapsuckers. However, these fam- 
ilies average less than 2 species each, while the native families, includ- 
ing the 258 species attacked, contain an average of 14 species each, 
so that our negative results for the former group are probably due in 
great part merely to the small amount of material examined rather 
than to the sapsuckers' distaste for trees of these families. 
Indeed it seems probable that practically all trees accessible to 
sapsuckers will sooner or later be attacked. The only widespread 
and numerous trees not yet known to be punctured are the mul- 
berries, Osage orange, and figs (family Moraceae), and the palms and 
yuccas belonging to the endogenous subclass of plants, in which the 
circulation of sap is peculiar, which are presumably unsuited to 
sapsuckers. 
The evidence shows that the three species of sapsuckers have prac- 
tically the same habits and consequent injurious effects upon trees. 
However, the Williamson sapsucker is not now known to harm trees 
of great value. Leaving this species out of consideration and speak- 
ing only of the red-breasted and yellow-bellied sapsuckers, the above 
detailed testimony abundantly confirms the conclusion drawn from 
the anatomical structure and stomach examination, namely, that 
sapsuckers habitually feed upon bast, cambium, and sap. It further 
shows that in securing their favorite food they often remove so much 
of the growing layer of trees that the vigor of the latter is impaired, 
sometimes to such a degree that death ensues. 
However strong seems the indictment against the sapsuckers, it 
must not be imagined that every tree pecked by them is doomed. On 
the contrary, they frequently work on a tree year after year without 
noticeably diminishing its vitality. Near Washington the writer has 
noted large elms whose trunks have evidently been attacked by many 
generations of sapsuckers and are freely drilled every year, but which 
to all appearances are now in perfect health. W. A. Taylor, of the 
Division of Pomology in the Department of Agriculture, states that 
at his home in southwestern Michigan there are several apple trees, 
now over 70 years old. which are known to have been yearly drilled 
by sapsuckers without diminishing their vigor or productiveness. The 
western half of the Department of Agriculture grounds at Washington 
contains 232 trees, of which 56 have been attacked by sapsuckers. 
