twenty-two days to its death, making from birth to death about 
one month. 
Charles Bonnet further discovered the fact that the young in 
their growth moulted four times, and you may find on the plants 
among the insects many white skins clinging to the plants. In 
fact, you may find some clinging to the young insects which are 
in the act of moulting. 
In the fall of the year another phase of the problem of re¬ 
production appears, for, at this time of year, both sexes of the 
insect—both winged forms—are present and a limited number of 
eggs are laid, by means of which the species is carried through 
the winter out of doors. These eggs hatch into wingless females 
upon the approach of warm weather, and the viviparous repro¬ 
duction begins again. The young hatched from the eggs are 
not in the larval form, but resemble the young of summer 
birth. 
If an insect passes regularly through the various stages of insect life, it 
is said to have a complete metamorphosis, as in the case of the cabbage 
butterfly, but if one or more of the stages is wanting, as in our present sub¬ 
ject, the metamorphosis is said to be incomplete. 
There is another appendage to the body of which we have 
not yet spoken; that is, a pair of tubes projecting from the end 
of the abdomen, about one-thirty-second of an inch long, from 
which is secreted a sweet fluid. In some plant lice the secre¬ 
tion of this fluid is excessive, and is known as "honey dew.” If 
it falls upon leaves, it makes their surface glossy, and pavements 
under trees attacked by many of these insects are made to look 
as if great drops of water had fallen from the trees. 
Now we come to another very remarkable fact in the life 
history of our subject and its kind, for this "honey dew” is a 
food material very much enjoyed by certain ants, and many 
naturalists have observed that ants run up cherry trees and other 
plants because of the presence of the plant lice there; and when 
a small globule of the "honey dew” appears at the end of one 
of these tubes, the ant seizes it before it drops to the ground. 
It is said, also, that this wise little ant understands that by agita¬ 
ting the honey tube with its antennae the secretion of the fluid 
is increased, and this phenomenon has been expressed by saying 
that the ant "milks” the plant louse, as man milks the cow. 
6 
