PLANT LICE. 181 
fellows gather about the opening buds, where they wait patiently, 
and perhaps shiveringly, too, so as to be ready to attack the first 
green growth that appears. These little lice that come from the 
eggs are of the form known as agamous females; that is, the 
females that produce young without the intervention directly of 
the opposite sex. These females are also viviparous, that is to 
say, their offspring are produced alive, which latter are also of 
a like nature. Just when the first winged specimens of this 
louse are to be found we do not know, nor are we prepared to 
Fic. 152.—Chaitophorus negundinis Thom.: a, apterous male; b, oviparous female; 
d, egg; all greatly enlarged; c,eggs on twigs, natural size. After Insect Lite, 
Diy. of Entomology, Dep. of Agriculture. 
give an outline history of their special mission in the cycle of 
this insect’s annual existence, further than, perhaps, to state that 
they are for the spreading of the species from one locality to 
another. The winged specimens, like the wingless agamous form, 
are also viviparous. In the fall of the year, after the first frosts, 
and when most of the leaves have fallen, the true female, which 
is a wingless form, lays eggs. These eggs are usually thrust 
into crevices of the bark, and between the buds and twigs. By 
