118 USEFUL BIRDS. 
ined these tents, and concluded to remove them. At that 
moment we were called to dinner, and left the trees for half 
an hour; when we returned, the largest tent had been torn 
open, and several dead caterpillars were scattered about that 
had been dealt with in the manner characteristic of the Ori- 
ole or the Chickadee. Several large holes in the web showed 
how they had been extracted. Being obliged to leave at 
once, I was unable to watch the tree, to see what bird was 
doing the good work; but Mr. C. Allan Lyford, who was 
‘with me, remained and photographed the caterpillars’ nest. 
The accompanying illustration made from his photograph 
shows plainly an opening made by the birds, as well as sev- 
eral of the dead caterpillars lying upon the limb or hanging 
from it. We did not take off the tents, but left them and 
their occupants to the tender mercies of the birds; and our 
confidence in their protective service was fully justified by 
the results observed later. 
But, it may be asked, why have not those who have dis- 
sected the stomachs of the birds discovered that they were 
eating hairy caterpillars? To this it may be answered that 
up to the present time most of the knowledge that has been 
gained in regard to the destruction of hairy caterpillars by 
birds has come from stomach examinations, and it is mainly 
by stomach examinations that light has been thrown on 
this question. Yet he who examines the stomachs of small 
birds labors under many difficulties in determining the specific 
character and quantity of this kind of food. Minute cater- 
pillars are speedily reduced to a pulpy mass in the bird’s 
stomach. While the field observer may readily identify the 
small tent caterpillars, for instance, on which the birds are 
feeding, and even count the number eaten, it might be im- 
possible for the man in the laboratory, working without exact 
knowledge of the conditions under which the bird was shot, 
to do either. Most of the larger caterpillars eaten by some 
of the smaller birds are not swallowed whole, but picked to 
pieces; therefore the portion of the caterpillar swallowed 
would be entirely unrecognizable when found in the bird’s 
stomach. Other caterpillars are dissected, as it were, by the 
bird, and only the internal parts chosen as food ; these can- 
