MIGRATIONS OF INSECTS. 267 



gregarious. Professor Bonelli, of Turin, however, 

 observed a similar flight of the same species of but- 

 terfly in the end of the March which preceded their 

 appearance at Grandson^ when it may be presumed 

 they were just evolved from their chrysalides. Their 

 flight, as at Grandson, was from south to north, and 

 their numbers were so immense that at night the 

 flowers were literally covered with them. As the 

 spring advanced their numbers diminished, though 

 even in June a few still continued. A similar flight 

 of butterflies is recorded about the end of last cen- 

 tury by M. Loche, in the Memoirs of the Turin 

 Academy. * 



The chief extraordinary migrations of insects which 

 have been recorded as occurring in Britain, are those 

 of aphides and their enemies, the lady-birds ( Coc- 

 cinellidce), which accompany them as whales follow 

 a shoal of herrings, or as the locust-eating thrush 

 of Southern Africa follows a swarm of locusts. ^ I 

 know no other reason,' says Kirby, ^ to assign for 

 the vast numbers that are sometimes, especially in 

 autumn, to be met with on the sea-coast, or the 

 banks of large rivers. Many years ago those of the 

 Humber were so thickly strewed with the common 

 lady-bird (^Coccmella septempundata), that it was 

 difficult to avoid treading on them. Some years 

 afterwards, I noticed a mixture of species collected in 

 vast numbers on the sand-hills on the sea-shore at the 

 north-west extremity of Norfolk. My friend, the 

 Rev. Peter Lathbury, made long since a similar ob- 

 servation at Orford, on the Suffolk coast : and about 

 five or six years ago (in 1807), they covered the 

 cliffs at Brighton, and of all the watering-places on 

 the Kentish and Sussex-coasts, to the no small alarm 

 of the superstitious, who thought them forerunners 

 of some direful evil, and who were ignorant that their 



* Mem. de la Soc. de Phys. et d'Hist. Nat. de Geneve. 



