IMPERFECT SOCIETIES OF INSECTS. 1] 
over a field of four acres as they passed.—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 (Cicada spumaria, L.), 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 wit- 
nessed, in August, a similar emigration of myriads of a 
kind of beetle (Carabus vulgaris, L.)".—Another writer 
in the same work, H. Kapp, observed on a calm sunny 
day a prodigious flight of the noxious cabbage-butterfly 
(Papilio Brassica, L.), which passed from north-east to 
south-west, and lasted two hours*. Kalm saw these last 
insects midway in the British Channel¢. 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 cab- 
bage 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, 
@ Naturforsch. vi. 111. b Thid. x1. 99. 
© Ibid. 94. 4 Travels, 1. 13. 
