PRACTICAL PAPERS—PLANT LICE. 
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This species is green, egg-shaped, one-tenth of an inch in 
length ; it is either with or without wings. They arc provided 
with two spurs, or nectaries, which originate near the center 
of the body. These nectaries secrete a fluid as sweet as honey. 
So astonishingly prolific is this insect, that the increase of one 
single egg, it has been estimated, in seven generations, wotild 
be 729 millions! If it weie not for the good offices of those 
animals which prey upon plant lice, every thing green on the 
face of the globe, would, in a short time, be covered with these 
voracious insects. They crowd as thick as they can stand, 
their long suckers inserted into the succulent young shoots 
and leaves, pumping up the juice. If disturbed, they jerk up 
their bodies in a comical way and emit, from their nectaries, a 
shower of honey, apparently to bribe the intruder with this 
sweet fluid. Not unfrequently they kick up their hind feet in 
unison, impelled by an excess of animal spirits, from very joy 
of existence. 
The history of this species is extremely interesting. In the 
spring, as scon as the young leaves appear, the eggs, hid away 
in the crevices of the bark, hatch. The young creep to the 
extremity of the branch and fasten to the young shoots. In a 
few days the louse is fully grown. All the eggs laid in 
autumn produce wingless females, and these females do not 
lay eggs, but bring forth living young which are also females. 
The young when first born are milk white, but change in a 
few hours to the color of the parent. In a very few days 
these young lice produce living progeny also. And so on for 
from fifteen to twenty generations, each individual louse pro¬ 
ducing from five to ten each day, all without the presence of a 
single male ; for in fact there is not a male in existence ! A 
few winged females appear occasionally, which take wing and 
plant new colonies. Thus goes on this remarkable form of 
reproduction till fall, when there appears a brood of winged 
males and females which pair, in the usual manner. The 
result of this union is not living aphides, but eggs, which in 
the month of October the females deposit in the crevices and 
cracks on the bark of apple trees. Soon after this the lice all 
