INSECTS AND VERMES. 463 



at all times, when winters are mild ; and are of great 

 service to those soft-billed birds that never leave us. 



On every sunny day the winter through, clouds of 

 insects, usually called gnats (I suppose Tipulce and 

 Empides) appear sporting and dancing over the tops 

 of the evergreen trees in the shrubbery, and frisking 

 about as if the business of generation was still going 

 on. Hence it appears that these Diptera'( which by 

 their sizes appear to be of different species) are not 

 subject to a torpid state in the winter as most winged 

 insects are. At night, and in frosty weather, and when 

 it rains and blows, they seem to retire into those trees. 

 They often are out in a fog 2 . 



HUMMING IN THE AIR. 



THERE is a natural occurrence to be met with upon the 

 highest part of our down in hot summer days, which 

 always amuses me much, without giving me any satis- 

 faction with respect to the cause of it ; and that is a 

 loud audible humming of bees in the air, though not 

 one insect is to be seen. This sound is to be heard 

 distinctly the whole common through, from the Money- 

 dells, to Mr. White's avenue gate. Any person would 

 suppose that a large swarm of bees was in motion, and 

 playing about over his head 3 . This noise was heard 

 last week, on June 28th. 



2 This I have also seen, and have frequently observed swarms of little 

 winged insects playing up and down in the air in the middle of winter, 

 even when the ground has been covered with snow. MARKWICK. 



3 I have frequently observed this humming in the neighbourhood of 

 London, in Copenhagen Fields, on Hampstead Heath, and at Shooter's 

 Hill, and for some time was as much puzzled to explain it as White : till 

 I, on several occasions, remarked a troop of swallows busily hawking 

 high overhead, where the humming was heard. There could be no 

 doubt, therefore, that it was occasioned by insects, invisible to me in 

 consequence of their distance. In another instance, I could plainly see 

 numbers of bees passing in their way to and from some blossomed lime 

 trees, as I supposed, which were at a good distance from the spot where 

 I stood the primary cause, perhaps, of their flying high. RENME. 



