114 THE ENEMIES OF BUTTERFLIES [ch. 



(mostly in Sunbirds) : millipedes in 20 ; but in no single 

 instance were the remains of butterflies found. More 

 recently Bates' account has been criticized by Swynner- 

 ton^ who comments on the difficulty of identifying 

 butterfly remains as compared with those of beetles 

 and grasshoppers. He states that the pellets ejected 

 by captive birds after a meal of butterflies contain only 

 fine debris which is very difficult to identify. Further, 

 he found that of twenty small bird excreta collected in 

 the forest no less than eighteen contained scales and 

 small wing fragments of Lepidoptera. 



Some attention has been paid to the relation be- 

 tween birds and butterflies in the United States, and 

 under the auspices of the Department of Agriculture 

 a large number of birds' stomachs have been investi- 

 gated. Careful examination of some 40,000 stomachs 

 of birds shot in their natural habitats resulted in the 

 discovery of butterfly remains in but four. It cannot, 

 therefore, be supposed that birds play much part in 

 connection with such mimetic resemblances as are 

 found in North America (cf. pp. 45-49). Nevertheless, 

 it is known that on occasion large numbers of butter- 

 flies may be destroyed by birds. An interesting case 

 is described by Bryant^ of an outbreak in North 

 California of Eugonia californica, a close relative of 

 the tortoiseshell. The butterfly was so abundant as to 

 be a plague, and five species of birds took advantage 

 of its great abundance to prey largely upon it. From 



1 Ibis, 1912. 



2 The Condor, vol. 13, 191^ pp. 195-208. 



