17 
extent, although from thence they derive their 
whole support. The observer will readily per- 
ceive that the Honey Dew is not gathered from 
the surface of the leaves, as supposed, but that 
the little animals evidently labour much in ex- 
tracting the juices from the tree or plant for 
their sustenance, and at different intei’vals, by a 
similar motion, they may be seen to eject this 
excrementitious substance, which I do not hesitate 
to affirm is the real cause of the Honey Fall, and 
that it is neither produced from the heavens, the 
air, nor the exudation of vegetation : I do not 
deny that a glutinous or clammy exudation does 
transpire from different trees and plants, but I do 
say that it is natural to those plants on which it 
is found, and mostly indicates health rather than 
disease, which is plainly represented by the Cis- 
tuses, the Acacia Gluttonosa, or Clammy Acacia, 
the Horse Chesnut, the Balsam Poplar, tlie To- 
bacco, and several other plants. 
The secretion of some other insects produces 
a similar effect to the Aphides, but not nearly so 
abundantly, especially some species of the Cocci, 
as will be seen on the various plants protected by 
glass. 
It has frequently been inquired why the 
Aphides prevail more some years than others, and 
it will afford me much pleasure if the following 
observations on that subject prove at all satisfac- 
tory : it is generally supposed that the weather 
has a ruling power over these little animals, but 
