MOST USEFUL BIRDS. 211 



the gypsy moth. It cannot be stated with certainty which 

 species is of most value in this respect, as the birds ob- 

 served vary both in numbers and usefulness with the locality 

 and season. From observations made eleven species are 

 known to be very useful. In the apparent order of their use- 

 fulness they are : yellow-billed cuckoo, black-billed cuckoo, 

 Baltimore oriole, catbird, chickadee, blue jay, chipping spar- 

 row, robin, red-eyed vireo, yellow-throated vireo and crow. 



FIG. 29. Yellow-billed cuckoo. 



The cuckoo is the only bird that I have found mentioned 

 in European literature as feeding commonly on the larvae 

 of the gypsy moth. Altum says the cuckoo is efficient 

 especially in local ravages of the moth.* Appearances in- 

 dicate that the cuckoos lead the rest of the American birds 

 in destroying the gypsy moth. Yet it must be considered 

 that as these cuckoos are comparatively large birds, seeking 

 by preference the larger larvae, their feeding is readily ob- 

 served. As the larvae are usually swallowed whole by the 

 cuckoo, their remains are readily recognized in the dissected 

 stomach. It is difficult to identify with certainty the smaller 

 larvae when they are eaten by small birds. If these small 

 birds consume the smaller larvae in numbers equal to those 

 of the larger ones eaten by the cuckoo, they are more benefi- 

 cial, as the destruction of the larvae when young will prevent 

 the injury they might do to vegetation before the cuckoo 

 would be likely to attack them. 



* " Forstzoologie," Vol. III., page 96. 



