396 NATURAL HISTORY 



became the next the most loathsome ; being enveloped 

 in a viscous substance, and loaded with black aphides, 

 or smother-flies. The occasion of this clammy appear- 

 ance seems to be this, that in hot weather the effluvia 

 of flowers in fields and meadows and gardens are drawn 

 up in the day by a brisk evaporation, and then in the 

 night fall down again with the dews, in which they are 

 entangled ; that the air is strongly scented, and there- 

 fore impregnated with the particles of flowers in summer 

 weather, our senses will inform us; and that this clammy 

 sweet substance is of the vegetable kind we may learn 

 from bees, to whom it is very grateful : and we may be 

 assured that it falls in the night, because it is always 

 first seen in warm still mornings 1 . 



On chalky and sandy soils, and in the hot villages 

 about London, the thermometer has been often observed 

 to mount as high as 83 or 84 ; but with us, in this hilly 

 and woody district, I have hardly ever seen it exceed 

 80; nor does it often arrive at that pitch. The reason, 

 I conclude, is, that our dense clayey soil, so much 

 shaded by trees, is not so easily heated through as those 

 abovementioned : and, besides, our mountains cause 

 currents of air and breezes ; and the vast effluvia from 

 our woodlands temper and moderate our heats. 



1 It will hardly be deemed a discredit to an observer so patient, so 

 accurate, and so faithful as Mr. White, to mention that his conjecture 

 concerning the origin of honeydew is erroneous. The subject has been 

 elucidated by the observation of Mr. William Curtis, who has discovered 

 that this substance is the excrement of the Aphides. See Transactions 

 of the Linnean Society, Vol.vi. No. 4. MITFORD. 



Had Mr. White carefully looked into the proceedings of the black 

 Aphides which he mentions, he would have found that the honeydew 

 was nothing more than their ejecta. In order to convince a friend who 

 was sceptical as to this undoubted fact, I placed a sheet of writing paper 

 under a branch where some Aphides were feeding, and over the leaves 

 below them, which I previously cleaned from honeydew. The result, as 

 I certainly anticipated, was, that the paper was soon covered with honey- 

 dew, while the leaves below it were free. RENNIE. 



