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- 



