IMPERFECT SOCIETIES OF INSECTS. 



11 



the noxious cabbage butterfly (Pontia Brassicce), which passed 

 from north east to south-west, and lasted two hours. 1 Kalm 

 saw these last insects midway in the British Channel. 2 A 

 similar migratory column of the universally spread Vanessa 

 Cardui, of from ten to fifteen feet in breadth, and the passage 

 of which occupied two hours, was observed in 1836 in the 

 canton of Vaud, Switzerland. 3 Lindley, a writer in the 

 Royal Military Chronicle, tells us, that in Brazil, in the 

 beginning of March, 1803, for many days successively there 

 was an immense flight of white and yellow butterflies, pro- 

 bably of the same tribe as the cabbage butterfly. They were 

 observed never to settle, but proceeded in a direction from 

 north-west to south-east. No buildings seemed to stop them 

 from steadily pursuing their course, which being to the ocean, 

 at only a small distance, they must consequently perish. It 

 is remarked that at this time no other kind of butterfly is to 

 be seen, though the country usually abounds in such a 

 variety. 4 In the instance of the butterflies, mostly of a 

 species similar to, if not identical with, the common English 

 Colias Edusa, seen by Mr. Darwin and Captain Fitzroy when 

 at sea, about ten miles from the bay of St. Bias, on the coast 

 of South America, and which were in such countless 

 myriads (occupying, according to Captain Fitzroy's calcu- 

 lation, a space of not less than a mile in width, several miles 

 in length, and two hundred yards in height) that the sailors 

 exclaimed, " it is snowing butterflies : " their object in flying 

 out so far to sea would seem to have been a voluntary mi- 

 gration, as Mr. Darwin states that the day had been fine and 

 calm. 5 Major Moor, while stationed at Bombay, as he was 

 playing at chess one evening with a friend in Old Woman's 

 Island, near that place, witnessed an immense flight of bugs 

 (GeocoriscB), which were going westward. They were so 

 numerous as to cover every thing in the apartment in which 

 he was sitting. When staying at Aldeburgh, on the eastern 



i Naturforsch. 94. 2 Travels, i. 1 3. 



3 Silbermann, Revue Entom. ii. 1 42. 



4 R. Milit. Chron. for March 1815, p. 452. 



5 Narrative of the surveying Voyages of his Majesty's Ships Adventure and 

 Beagle, iii. 185. 



