IMPERFECT SOCIETIES OF INSECTS. 11 



stances are given by Rosel of similar clouds of these 

 insects having been seen in Silesia and other districts", 

 -^Professor Walch states, that one night about eleven 

 o'clock, sitting in his study, his attention Avas attracted 

 by what seemed the pelting of hail against his window, 

 Avhich 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 spwnaria, L.), 

 which entered the room in such numbers as to cover 

 the table. From this circumstance and the continu- 

 ance 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 

 Avindow faced the south, they only glanced against it 

 obliquely''. He afterwards witnessed, in August, a 

 similar emigration of myriads of a kind of beetle (Ca~ 

 rabus 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 Brus- 

 sica^, L.), which passed from north-cast to south-west, 

 and lasted two hours '^ Kalm saw these last insects 

 midway in the British Channel^. Lindley, a writer 

 in the Royal Militari/ Chi^onicle, tells us, that in Bra- 

 zil, in the beginning of March 1803, for many days 

 successively there was an immense fliglit of white and 

 yellow butterflies, probably of the same tribe as the 

 cabbage-butterfly. They were observed never to set- 

 tle, 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 



^ ii. 135. " Naturfonch. vi. 111. " Ihid. \\. 95. 



" Ibid, 94. " Travels, i. 13. 



