190 BUTTERFLIES AT NIGHT 



the Satyrinae, which in the troj^ics are accustomed 

 to fly by twilight and even in the rain. 



My attention was early called to the occurrence 

 of butterflies far out at sea by seeing, on my fli'st 

 natural history expedition nearly forty years ago, 

 a specimen of the Mourning Cloak (Euvanessa 

 antiopa), which visited our vessel on the 26th of 

 February, while off the coast of North Carolina 

 and some twenty or thirty miles from land, mak- 

 ing us a short and flighty visit^ One of the most 

 remarkable instances, however, is that related by 

 Darwin in his " Naturalist's Voyage around the 

 World": — 



"One evening [he says], when we were about ten 

 miles from the Bay of San Bias [northern Patagonia], 

 vast numbers of butterflies, in bands or flocks of count- 

 less myriads, extended as far as the eye could range. 

 Even by the aid of a telescope it was not possible to see 

 a space free from butterflies. The seamen cried out 

 ' It was snowing butterflies,' and such in fact was the 

 appearance. More species than one were present, but 

 the main part belonged to a kind very similar to, but 

 not identical with, the common English Colias edusa. 

 Some moths and Hymenoptera accompanied the butter- 

 flies ; and a fine beetle (Calosoma) flew on board. . . . 

 The day had been fine and calm, and the one previous 

 to it equally so, with light and variable airs. Hence 



