122 ANNUAL REPORT. 
There are a great many species of plant-lice, distinguished mainly by the 
plants upon which they feed, or by the effects they produce by their punc- 
tures. They all have jug-shaped or egg-shaped bodies, jointed beaks, two- 
jointed feet, and, in certain stages of their existence, two pairs of glassy 
wings, with few straighv veins, the upper pair having a dark or opaque 
pane on the front edge. They multiply, both by eggs and viviparously, by 
a very singular sort of animal budding process. The majority of the 
species are provided with two little hollow projections, situated on the 
hinder part of the back, which are called ‘‘ honey-tubes,” through which the 
superfluous juices of the plant, with which the insects gorge themselves, 
are discharged. This sweet and sticky fluid is sometimes so abundant as to 
smear and drop from the leaves of Aphis-infested plants, and forms the 
**honey-dew ” most commonly observed. It is for the sake of this ** honey” 
that the ants are always attendant on plant-lice, and notwithstanding their 
usual carnivorous propensities, never kill them, but, on the contrary, will 
often fight violently to protect them. 
The different species of plant lice vary much in color and size, some have 
the body smooth and glossy, others are covered with a powdery ‘‘ bloom,” 
others still are clothed in a cottony matter that quite conceals their color 
and in some instances their form. Some species live openly on leaves, 
stems and buds, others inhabit galls, or wart-like excresences caused by 
their punctures, others still are subterranean and feed upon roots. A few 
kinds, like the notorious Grape Phylloxera, and the Woolly Apple-louse, 
exist in one stage above ground on the leaves, and in another underground 
on the tenderest roots. 
Mode of Development. 
The mode of development in the plant-lice is pretty much the same in all 
the species. The winter is passed in the egg state. From these eggs, in 
the spring, hatch wingless, organic females which produce their young alive, 
one at atime, but in quite rapid succession. These in turn, in the course 
of a few days, begin to multiply in the same way, and so on, for five or six 
generations, all being females. Then a brood will be produced, also all 
females, which will develop wings and fly away from the plant on which 
they were born, to spread their kind on other plants or trees. Towards 
fall a brood of the lice will appear which are the true males and females, 
usually wingless in both sexes—the females invariably so. These lay the 
winter eggs. Ina very few species the eggs hatch before cold weather sets 
in, and the young lice, fixing their beaks in the tenderest twigs, bibernate 
in a dormant condition. It has been very difficult to trace the life history 
of these insects, owing to their peculiar and varying modes of develop- 
ment. It was, until very recently, supposed that the winged insects were 
in all cases the perfect males and females; but the observations of French 
and German entomologists, and of Prof. Riley, Mary E. Murtfeldt, and 
others of our own country, proved that this was a mistake, and, by means 
of numerous and careful investigations, ascertained the true history of the 
most important species. 
