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in confined positions and subject to its action, as in Galls and subter¬ 
ranean situations. The value of this mealy secretion to these insects 
can readily be tested by putting a small drop of water into the midst 
of a colony of the Elm-leaf Aphis (Schizoneura ulmi) ; or it may be 
seen in some of the larger galls made by Pemphigi, where small drops 
of fluid may be seen rolling about, apparently without in the least dis¬ 
commoding the inhabitants. 
The little shining, colorless, spherical bodies which can be seen 
rolling about among the colonies of the Elm-leaf Aphis, when we 
handle the curled and distorted leaves, according to Buckton, consist 
of fiecal matter discharged from the anal aperture. They are some¬ 
times taken by mistake for eggs. 
As is well known to all who have studied with any degree of care 
the habits of insects, galls are produced by species of several different 
orders, and that, as a rule, each species forms a gall of a peculiar shape. 
Although not confined wholly to this sub-family yet it is here we 
find the gall-making habit chiefly developed; and in fact confined 
mostly to the species of the true Pemphigini included in section two 
as below explained. What particular agency is employed and how 
developed to form these galls is yet an unsolved mystery. Blot says, 
the female inserts an egg under the surface of the young leaf in the 
tissue and that the gall grows up around it, or to use his words, “is 
born upon the surface.” But the peculiar character of the gall does 
not appear to agree with this statement. Instead of being true, closed 
galls they are, in fact, abrupt, purse-like foldings of the entire thickness 
of the leaf-blade, leaving a narrow opening on the side opposite to 
the gall for the escape of the insects, which having no means of eat¬ 
ing their way out, would otherwise be hopelessly confined in a prison 
of"their own building; the galls formed by mites are similarly con¬ 
structed. In reference to the method of passing the winter, it appears 
to be generally conceded by entomologists that, as a rule, it is in the 
egg state. I have some reason to question this conclusion if it is to 
be applied to all the species. My reason for this doubt will be given 
when I come to describe the Wooly-Aphis of the Apple-tree (Schizon¬ 
eura lanigera). I am inclined to believe some if not all, the species 
of this sub-family will approach more nearly to Phylloxera in their 
mode of reproduction and of passing the winter than to the true 
Aphidini . 
As a general rule the species are serial, that is, they reside- ex¬ 
clusively above ground, but one or two at least and in all probability 
some others of the trunk-inhabiting species, penetrate to the roots and 
become subterranean; whether these can be considered as true dimor¬ 
phic forms has not as yet been satisfactorily determined. 
This sub-family, as above indicated, may properly be divided into 
two or three different sections. The following arrangement appears 
to me to be the most natural. 
A. Third discoidal vein of the front wings twice forked. 
a. Antennae six-jointed. Sec. 1 . Schizoneurini. 
aa. Antennae five-jointed. Sec. 2. Vacunini. 
