> 'I EASTERN PENNSYLVANIA. 303 



The period of time devoted to nest-building 

 depends materially upon the style of the nest and 

 the character of the builders. The nest being 

 completed, oviposition commences the following 

 day, and proceeds at the rate of one egg per day, 

 and lasts from four to five days. Incubation 

 ensues the succeeding day, and continues for ten 



days; the male occasionally relieving his mate; 



* </ <_> 



but the chief part of the responsibility devolves 

 upon her. Whilst the female is thus occupied, 

 the male carefully attends to her wants. 



These Sparrows are devoted parents, expressing 

 considerable anxiety when their nests and young 

 are interfered with. The young are feel with the 

 larv;i' of small insects chiefly of a le'pidopterous 

 < haraclor. Various diptera and coleoptera, consti- 

 tute a meagre portion of their diet; but the cater- 

 pillars of Anisop!crv.\~ -ccniata, A. pornctaria, Zercne 

 caicnaria, Ennomos subsignaria, are devoured in 

 prodigous numbers, besides those of Pieris rapcc, 

 Colitis pJiilodice, Asopia costalis, Gortyna zea> 

 Plnsia precationis, Agrotis tessellata, (. Icjiucka I /"/'- 

 g;.nira< and mature forms of Musca domestica, 

 Tabamis lineola, Stomoxys calcitrans, and earth- 

 worms, aphides, ants, and mosquitos. 



In about twelve days the young are able to leave 

 the nest, and in eiijht or nine clays more, are suf- 



<7^ * 



ficiently matured to look after their own welfare; 

 they still, however, consort with their parents, and 

 both young and old forage together. In this lati- 

 tude there is only a single brood in a season. 



