APHIS. 175 



" In the height of Summer, when the weather 

 is hot and dry, and Aphides are most abundant, 

 the foliage of trees and plants, (more especially in 

 some years than others) is found covered with and 

 rendered glossy by a sweet clammy substance 

 known to persons resident in the country by the 

 name of honey-dac : they regard it as a sweet sub- 

 stance falling from the atmosphere, as its name 

 implies. The sweetness of this excrementitious 

 substance, the glossy appearance it gave to the 

 leaves it fell upon, and the swarms of insects this 

 matter attracted, first led me to imagine that the 

 honey-dew of plants was no other than this secre- 

 tion, which farther observation has since fully con- 

 firmed. Others have considered it as an exsuda- 

 tion from the plant itself. Of the former opinion 

 we find the Rev d . Mr. White, one of the latest 

 writers on natural history that has noticed this sub- 

 ject. But that it neither falls from the atmosphere, 

 nor issues from the plant itself is easily demon- 

 strated. If it fell from the atmosphere, it would 

 cover every thing indiscriminately, whereas we 

 never find it but on certain living plants and trees. 

 We find it also on plants in stoves and green- 

 houses covered with glass. If it exsuded from the 

 plant, it would appear on all the leaves generally 

 and uniformly ; whereas its appearance is ex- 

 tremely irregular, not alike on any two leaves of 

 the same tree or plant, some having none of it, 

 and others being covered with it but partially. 

 But the phenomena of the honey-dew, with all 

 their variations, are easily accounted for by con- 



