IMPERFECT SOCIETIES OF INSECTS. 295 



Asthelocust-eatingthrush (Turdus Gryllivorus} accompanies the locusts, 

 so the lady-birds (Coctinella) seem to pursue the Aphides ; for I know no 

 other reason to assign for the vast number that are sometimes, especially 

 in the 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 (C. Seplempunctata), that it was difficult to 

 avoid treading upon 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 observation at Orford, on the Suffolk coast ; and 

 about five or six years ago they covered the cliffs, as I have before remarked, 

 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. 1 These last probably emigrated with the Aphides from the 

 hop grounds. Whether the latter and their devourers cross the sea has 

 not been ascertained ; that the Coccinellae attempt it, is evident from their 

 alighting upon ships at sea, as I have witnessed myself. 2 This appears 

 clearly to have been the case with another emigrating insect, the saw-fly 

 (Athalia centifolwe) of the turnip. 3 It is the general opinion in Norfolk, 

 Mr. Marshall informs us 4 , that these insects come from over sea. A farmer 

 declared he saw them arrive in clouds so as to darken the air ; the fisher- 

 men asserted that they had repeatedly seen flights of them pass over their 

 heads when they were at a distance from land ; and on the beach and cliffs 

 they were in such quantities, that they might have been taken up by shovel- 

 fuls. Three miles inland they were described as resembling swarms of bees. 

 This was in August, 1782. Unentomological observers, such as farmers 

 and fishermen, might easily mistake one kind of insect for another ; but 

 supposing them correct, the swarms in question might perhaps have passed 

 from Lincolnshire to Norfolk. Meinecken tells us, that he once saw in a 

 village in Anhalt, on a clear day, about four in the afternoon, such a cloud 

 of dragon-flies (Libellulina) as' almost concealed the sun, and not a little 

 alarmed the villagers, under the idea that they were locusts 5 ; several 

 instances are given by Rosel of similar clouds of these insects having been 

 seen in Silesia and other districts 6 ; and Mr. Woolnough of Hollesley in 

 Suffolk, a most attentive observer of nature, once witnessed such an army 

 of the smaller dragon-flies (Agrion) flying inland from the sea as to cast a 

 slight shadow over a field of four acres as they passed. A migration of 

 dragon-flies was witnessed at Weimar in Germany in 1816, and one far 

 more considerable, perhaps the greatest on record, May 30th and 31st 



1 Some such terrific idea would seem to have entered the sapient heads of the 

 authorities of one of the principal towns of Berkshire, which in October, 1835, ac- 

 cording to the Reading Mercury, having had " a most formidable invasion of this 

 beautiful insect [lady-birds] . . . the parish engines, as well as private ones, were 

 called into requisition, with tobacco-fumigated water, to attack and disperse 

 them." [ ! ! !] 



2 Mr. Curtis informs us that the aphidivorous flies ( Scceva Ribesii, Pyrastri, &c.), 

 like the lady-birds, sometimes appear in myriads on the sea-coast, all flying in one 

 direction, and not even avoiding objects that lie in their course. (Brit. Ent. 

 fol. 509.) 



3 Fn. Germ. Inlt. xlix. 18. * Philos. Trans. Ixxiii. 217. 

 5 Naturforsch. vi. 110. 6 ji. 135. 



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