782 
ANNUAL REPORT OF NEW YORK 
OAK. HOOT. 
upon the surface of the snow, on mild days in the fore part of winter. The 
warmth of the trunks of the trees melts the snow where it is in contact 
with them, as every woodman is aware, producing a crevice or vacant space 
down to the ground immediately around the tree; and I infer that it is 
through this opening that these insects ascend from the roots of the trees, 
and wander about upon the snow, to find and pair with their mates, after 
which they again descend to insert their eggs in the roots; for it is at this 
period of the year that their eggs are deposited, as we learn from seeing 
them frequently extruded by recently captured individuals. Their eggs 
are minute oval white grains, and are coated over with a glutinous white 
fluid, by which, when the female is impaled, they are held together in a 
continuous string. And this substance, in which the eggs of these as of 
other gall-flies are enveloped, is supposed by its acridity to produce the 
irritation of the vegetable tissues which causes the growth of the singular 
tubers and excrescences in which the young of these insects are cradled. 
The genus Biarhiza is defined by authors as being destitute of wings 
and having the antennm composed of fourteen joints in the females. It may 
further be added that these organs are thread-like and nearly as long as 
the body. The abdomen also is strongly compressed, as it is in the flea, 
to which insect these wingless gall-flies have tfonsiderable resemblance. 
When viewed in profile the abdomen is broad egg-shaped with its smaller 
end attached to the thorax ; its sutures are marked by fine impressed trans¬ 
verse lines ; and its first segment is very large, about equal in length to all 
the remaining segments. The abdomen is much more smooth and shining 
than the head and thorax, which are bearded with minute gray hairs, the 
head being broader than the thorax, and appearing about twice as broad as 
long when viewed from above. 
We have in the State of New York three insects which will pertain to 
this genus as above characterized. One of these may appropriately be 
named from its color, 
290. The Black gall-fly, Biarhiza nigra, new spccica. (Hymcnoptera. CyDiphidsE.) 
This is of a black color throughout, including its feet and antennae, and 
like the kindred European species, it is destitute of any vestiges of wings. 
It measures but eight hundredths of an inch (0.08) in length. 
The two other species to which I have alluded, possess abortive or 
rudimentary wings, in the form of small whitish and feebly transparent 
scales, reaching about a third of the length of the abdomen. These scales 
are of a long oval shape, rounded at their tips, and are densely covered 
with minute punctures, and bearded with exceedingly fine short hairs. A 
straight sub-costal or rib-vein of a brown color, extends about half their 
length, parallel with the outer margin, and ends abruptly without curving 
towards the margin. The scales representing the hind wings are shorter 
and narrower than the forward ones. In addition to the difference now 
stated, the last segment on the under side of the body, from out the hind 
edge of which the ovipositor is protruded, is much more strongly elevated 
