378 THE BUTTERFLIES OF NEW ENGLAND. 



February, while off the coast of North Carolina and some twenty or thirty 

 miles from land, making us a short and flighty visit. One of the most re- 

 markable instances, however, is that related by Darwin in his "Naturalist's 

 voyage around the world," p. 158 : " 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 countless 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. JNIore 

 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 butterflies; 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 we 

 cannot suppose that the insects were blown off the land, but we must con- 

 clude that they voluntarily took flight." 



Observers in India and other tropical regions have noticed on many 

 occasions vast swarms of Pierinae moving in a line along the sea coast, and 

 occasionally such swarms have been seen in similar situations in temperate 

 regions; thus Dr. Schulte (Ent. nachr., iii : 71) relates that in a dead 

 calm off Nordeney in the Baltic Sea, he steamed for three hours and a dis- 

 tance of thirty miles through a continuous flock of Pieris rapae from ten to 

 thirty miles from the main land and only five miles less than that from the 

 nearest island ; afterward the shore was found strewn with their dead bodies. 

 And on our own side of the ocean we have a curious instance related of 

 Eurema lisa by Mr. J. M. Jones, who states that early one October morn- 

 ing several persons living on the northern side of the main island of 

 Bermuda perceived what they thought to be a cloud coming from the north- 

 west, which turned out to be "an immense concourse of small yellow butter- 

 flies, which flitted about all the open grassy patches and cultivated grounds 

 in a lazy manner, as if fatigued after their long voyage over the deep," and 

 fishermen out that morning stated that their boats were literally covered 

 with these butterflies. Other instances are recorded by Caldcleugh and 

 Cornelius. I have elsewhere recorded the tendency of Anosia plexippus to 

 swarm along the water edge as if preparing for a great flight, and also the 

 fact that this butterfly must have flown vast distances over the Pacific 

 Ocean to have tenanted the scattered islands where it is now found. Also 

 that it was seen by one naturalist in the south Pacific five hundred miles 

 from the nearest island, and on the Atlantic ocean "hundreds of miles 

 from land." There is also a sing^le record of tlie occurrence of Pieris 

 rapae on one of the transatlantic steamers, when more than a thousand 

 miles from land (Psyche i: 152). This last might j^erhaps be accounted 

 for on the supposition that the insect had emerged from a chrysalis on 



