398 RELATIONS OF BIRDS TO AGRICULTURE 



apple, mountain ash, evergreens, and other trees, sucking the sap, 

 of which it appears to be very fond, and leaving rows of holes 

 about the trunk. Some of the cambium or inner layer of the bark 

 seems to be eaten also. While this bird eats a few insects, the 

 damage it does in causing trees to bleed far outweighs, we believe, 

 the benefits derived from its presence. In striking contrast with 



FIG. 391. Yellow-bellied sapsucker. (After Fuertes.) 



other birds whose tongues are adapted for extracting borers from 

 infested trees, the tongue of this species has a somewhat " brush- 

 like" tip. It can not be protruded to any extent, and is thus 

 suited to an entirely different diet from that of other members 

 of the same family. The rows of holes made by this bird upon 

 tree-trunks may result in girdling the tree. 



