BIRDS, CATEBPILLABS, AND PLANT LICE. 119 



not be identified in the stomach of a bird. Orioles, Vireos, 

 and Titmice are among the birds that commonly dissect 

 caterpillars in this way. This is not a rare or exceptional 

 habit, nor is it difficult to observe. It seems to be a device 

 adopted by certain of the smaller birds mainly when feeding 

 on caterpillars too large to be swallowed whole without caus- 

 ing some inconvenience ; therefore, they choose the parts 

 which can be digested readily, and reject the others. 



There are two facts which have gone far to justify the con- 

 clusions of those Avho believe that liirds do not eat hairy cat- 

 erpillars ; they are : (1) most birds appear to prefer hairless 

 caterpillars with which to feed their young ; (2) when small 

 hairless caterpillars are abundant, most birds seem to prefer 

 them to large hairy caterpillars. The first statement may 

 be accepted as a rule ; nevertheless, fifteen species of birds 

 were seen by my assistants in the act of carrying away hairy 

 larv.T apparently to feed their young, and some of these were 

 actually seen to put large hairy caterpillars down the throats 

 of the young birds. These fifteen species are j the Robin, 

 Wood Thrush, Catbird, Chickadee, Chestnut-sided War- 

 bler, Yellow Warbler, Black and White Warl)ler, Yellow- 

 throated Vireo, Eed-eyed Vireo, Scarlet Tanager, Crow, 

 Blue Jay, Baltimore Oriole, Black-billed Cuckoo, and Yel- 

 low-billed Cuckoo. Statement No. 2 is proved by records 

 made by several observers, in }'ears when cankerworms 

 were abundant. They found that when birds had for some 

 time been feeding on the hairy cater|)illars of the gipsy moth 

 they neglected these larvae, for a time, at least, to feed on 

 the 3'oung cankerworms. While the above observations 

 show that the hairy caterpillars are not s(^ eagerlv sought 

 after by most birds as are many hairless kinds, and that the 

 hairy species enjoy seasons of partial immunity from the at- 

 tacks of birds, they form no adequate excuse for the sweep- 

 ing, erroneous generalizations regarding this subject that 

 have been given a wide circulation. 



If we turn to the literature of economic entomology, we 

 shall find many records which are corroborative of my state- 

 ments. The occurrence of the great flight of Starlings and 

 other birds that flocked to feed on the caterpillars of the nun 



