HEARING IN INSECTS. 89 



are eradicated is perfectly mute; but John Hunter 

 affirms, that though the wings be cut off and the legs 

 held fast, they can still emit a shrill, peevish sound, 

 as they can also do when their wings are smeared over 

 with honey, and even when they are held under 

 water, which he observed to vibrate at the point of 

 contact with the air-holes at the root of the wings*. 

 A French naturalist infers from Hunter's experiments, 

 that the hum is rather caused by a tremulous affection 

 of the entire body, than by the strong vibration of the 

 upper wings f. That it is not the wings alone which 

 produce the sound is proved by the well-known fact, 

 that many insects of the same order fly silently J. 



White, of Selborne, observed a sound like that of 

 bees, for which he could not account. " There is," 

 he tells us, " a natural occurrence to be met with in 

 the highest part of our down, on the hot summer 

 days, which always amuses me much, without giving 

 me any satisfaction as 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. Any person would 

 suppose that a large swarm of bees was in motion 

 and playing about over his head ." We have fre- 

 quently observed this humming in the neighbourhood 

 of London, in Copenhagen Fields, on Hampstead 

 Heath, and at Shooters' Hill, and for some time were 

 as much puzzled to explain it as White ; till we, 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 us in conse- 

 quence of their distance. In another instance, we 

 could plainly see numbers of bees passing and re- 

 passing at a very considerable height, in their way to 

 and from some blossomed lime-trees, as we supposed, 



* Phil. Trans, for 1792. t Diet, des Sciences Naturelles. 



J Kirby and Spence, Intr. ii. 379. Nat. Hist.ii. 



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