OF EASTERN PENNSYLVANIA. 63 



strays from the other, as soon as it becomes con- 

 scious of the fact, it utters its usual call-notes 

 which are instantly responded to by the other, 

 when within hearing distance. A similar succes- 

 sion of notes is heard when a booty is discovered 

 to which it desires to summon the other. We are 

 informed by a friend of considerable experience, 

 and whose reliability is unquestioned, that other 

 species frequently respond to these calls. 



Its flight is high, well sustained, and character- 

 ized by notable firmness and celerity. 



The syllables tschlca-dee-dee-dee repeated quite 

 loudly and with a clear, distinct, and resonant ex- 

 pression, are often heard in the intervals of feeding. 

 When alarmed even by the movements of the 

 squirrel or other small animals, these notes are 

 exchanged for the hoarse cries of day-day-day 

 which are often taken up by many individuals at 

 once, producing a perfect medley of inharmonious 

 soufids. 



The food of the Black-cap consists principally 

 of insects. Their eggs, larvae and imagos are 

 sought after and devoured with avidity. Even 

 chrysalides, however large, do not resist its 

 assaults. The following beetles constitute a con- 

 spicuous portion of its diet: Rynchoeiis pini.Bos- 

 trichus pini, Cr atony chus compar, Chrysomela 

 cczruleipennis, Platynus cupripennis, Harpalus cal- 

 iginosus, and others. Among lepidoptera, Clisio- 

 campa Americana, Anisopteryx vernata and other 

 geometers, besides many of the Noctuidcz and 



