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be formed thereon. The effect of this, when the roots are badly 
infested, especially of young trees and nursery stock, is to cause them 
to become sickly and finally die. Where they are sufficiently numerous 
to covei and deform the root of a tree, the root almost invariably 
rots, then the lice leave it. As a matter of course, the effect produced 
by these insects on a young tree is much sooner perceived than on those 
that are older and larger. Prof. Riley found, from some observations 
made by him on an orchard at St. Louis, that . young nursery trees, 
whose roots were badly infested, diedthe following season, the roots 
always rotting previous to the death of the tree. He appears also to 
think this rot can be distinguished from that produced by any other 
cause, by its being more porous and soft, and approximating the brown 
mould of a rotting log. Although there is a tendency in the deformi¬ 
ties to disappear when the exciting cause is removed, yet where the 
lice only leave because it is dying, it appears scarcely possible that the 
deformities should entirely disappear, as the only means of removing 
them is gone when vitality is wanting; and these, if remaining, would 
indicate at once the cause'of the rot. Most orchardist sare aware, that 
the work of these insects can generally be detected where they have 
been working about the collar of the trunk, even after they have 
disappeared; there is a peculiarity in the appearance of the bark, a 
roughened or shagreened appearance, it looking as though the thin 
delicate outer layer of bark or epidermis had been removed. If present, 
they may easily be recognized by the peculiar bluish white, cottony 
matter they secrete from their bodies, which is never met with in the 
case of the common Apple-tree Plant-louse (Jlphis vncili ). I he same 
thing is also true in reference to the spots on the trunk and branches 
which they attack. When they locate on these portions of the tree, 
thev usually, and so far as my observations go, always select as a 
starting point, some fissure, cut, break or otherwise injured portion of 
the bark; or if these cannot be found, the wrinkles about the axils or 
forks of the larger limbs and elsewhere. I noticed some the past 
summer, in little scattered colonies, on the smaller limbs and even 
twigs of an apple-tree standing in my yard. If a tree is neglected 
and allowed to send up sprouts from the base of the trunk, the point 
where these join the trunk at or below the surface will be found a 
favorite resort for these insects. 
Do they pass from the trunk and branches to the roots? Or, in 
other words what relation do the two races bear to each othci ? 
Dr. Fitch thinks the parent insect insinuates hereself downward, 
along the side of the root, at the close of autumn, and. there deposits 
her eggs and perishes; that these eggs hatch in the spring, as soon as 
the ground becomes sufficiently warm, and that the colony is continued 
through the season by the viviparous propagation usual with the aphides; 
that in the autumn following, winged individuals again appeal, and 
leaving the ground, seek new homes. 
So far as the method of piopagation is concerned, it has been shown 
by Dr. W. M. Smith, of New York, that it differs slightly from the 
true Aphides, in that the young larva produced by the agamic fe¬ 
males are inclosed in the thin egg shaped covering heretofore men¬ 
tioned, from which they have to free themselves in a manner analo¬ 
gous to hatching. The remains of this covering may often be seen 
attached to the" tip of the abdomen, and is doubtless the supposed 
