THE PLANT LOUSE. 
437 
it prove a female, it will produce young : In like man- 
ner, the young produced from this virgin loufe, kept fe- 
parately, will produce an offspring. Some naturalifts 
have repeated this experiment to the third and fourth re- 
produ&ion. Bonnet obferved nine fucceflive generations 
of this nature, ail in the fpace of three months. The moil 
probable account of this Angular facl feems to be this ; 
that as in all animals fecundation is accomplifhed by the 
copulation of male and female ; fo that happens with the 
plant lice ; but with this difference, that the fecundation- 
produced by that act is tranfmitted for feveral genera- 
tions, before the prolific virtue becomes entirely ex- 
haufled. 
The young, immediately after being protruded from 
the mother, are al vays of a paler colour than the parent; 
They have then the entire ufe of their limbs, and go in 
quell of food. All the different kinds caft their ikin ; 
and it is after thefe devclopements that fuch of them as 
have wings obtain tbefe parts. 
It is not the males only that are winged, as we have 
feen in fome other genera; many of the plant lice of 
ioth fexes are deprived of thefe inflruments in their moft 
perfe£t {late ; for many of the females without them are 
ieen producing young. As the larva: of thefe infects 
pofilfs all the a&ivity peculiar to their genus in its lafl 
ftage of growth, fo they are equally diflinguifiied by vo- 
racity. They are furnifhed with a fmall trunk, which 
pierces the leaves, and enables the animal to extract the 
juices proper for its nourifhment. Many plants grow 
deformed by the number of pnnftures thus made upon 
their leaves, and decay from the want of their ufual fap. 
Some thrive even when covered with thefe infe£ts , while 
ethers rife up into fmall hollow tubercles, which, on 
being 
