296 ‘ IMPERFECT SOCIETIES OF INSECTS. 
1839, when cloud-like swarms of these insects (chiefly L. depressa) were 
seen at Weimar, Eisenach, Leipsig, Halle, and Gottingen, and the inter. 
vening country, extending over a very large district.1 Professor Walch 
states, that one night about eleven o'clock, sitting in his study, his attention 
was attracted by what seemed the pelting of hail against his window, which 
surprising him by its long continuance, he opened the window, and found 
the noise was occasioned by a flight of the froth frog-hopper (Aphrophora 
spumaria), which entered the room in such numbers as to cover the table, 
From this circumstance, and the continuance of the pelting, which lasted 
at least half an hour, an idea may be formed of the vast host of this insect 
passing over. It passed from east to west ; and as his window faced the 
south, they only glanced against it obliquely. He afterwards witnessed, 
in August, a similar emigration of inyriads of a kind of ground beetle 
(Amara vulgaris).3 But the most remarkable migrations of beetles are 
those recorded by M. Lacordaire, who informs us that for two successive 
years, when he was at Buenos Ayres, that city was for about eight days in 
the spring of each year inundated by such millions of Hanpalus cupripennis, 
which arrived daily towards nightfall, that it was necessary every morning 
to sweep them from the exterior of the houses to a height of several feet 
above the ground.* Another writer in the Naturforscher, H. Kapp, ob- 
served on a calm sunny day a prodigious flight of the noxious cabbage 
butterfly (Pontia Brassice), which passed from north-east to south-west, 
and lasted two hours. Kalm saw these last insects midway in the British 
Channel.® 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, Switzer- 
land.’ 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, probably 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. 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. Blas, on the coast of South 
America, and which were in such countless myriads (occupying, according 
to Captain Fitzroy’s calculation, 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 migration, as Mr, Darwin states 
that the day had been fine and calm.® Major Moor, while stationed at 
! Weissenborn in Mag. Nat. Hist. N.S. iii, 516. 
2 Naturforsch, vi. 111, 5 Ibid. xi. 95. 
4 Lacordaire, Introd. 4 ? Entom. ii, 494. 
5 Naturforsch, 94. 6 Travels, i, 13. 
7 Silbermann, Revue Zntom. ii. 142. 
8 Rt. Milit. Chron. for March 1815, p. 452. 
® Narrative of the surveying Voyages of his Majesty's Ships Adventure and 
Beagle. iii 185 
