482 
ANNUAL REPORT OF NEW-YORK 
SUPPLEMENT. 
of short pale yellow hairs evenly shorn at their tips and projecting out from 
the surface, and opposite these tufts on the inner surface is a small round spot 
of the same yellow color, formed of exceedingly fine lines radiating from the 
centre to the outer margin of the spot, which is bounded by an elevated ring 
or hoop which is also of a pale yellow color. From this description the ento¬ 
mologist will perceive that the pupa-case of this fly is analogous in almost 
every particular with those of many other insects of this order. 
The fly is a female and measures 0.70 in length to the tip of its abdomen 
and wings. Its head is black above, with close fine punctures, and is densely 
covered with short erect black hairs; its under side is brownish flesh-colored, 
closely punctured and clothed with white hairs which incline inward towards 
the mouth. Upon each cheek, below the eye and adjacent to the outer edge 
of its orbit, is a large shining black dot, in which the punctures are coarser 
and more distant from each other, and the space between this and the eye is 
darker brown. The antennae are dark liver-brown and have a few whitish 
hairs overlying their bases, like eye-lashes. Their bristle is black at its base 
and the fine hairs with which it is ciliated are whitish. The cavity in which 
the antennae repose has an ash-gray reflection, and on each side between this 
cavity and the eye is an elevated smooth shining space which is coarsely 
punctured. The thorax is black, finely punctured and clothed with soft hairs 
which incline backwards and appear of a tawny brown color when viewed 
from above but when seen from the side are white slightly tinged with yellow. 
Upon each side these hairs are much more dense, and half way from the wing- 
socket to the lower edge of the eye is a dot formed of black hairs. The scutel 
is black and clothed with black hairs. Beneath it on ench side is a small yel¬ 
lowish-white dot, from which a short white line extends outwards. The 
abdomen is black, shining, densely punctured and covered with fine short hairs 
which incline backwards, those at the base being longer and those on the last 
segment tawny yellowish-white when viewed laterally but appearing black 
when seen from above. The segments are prolonged to the under side of the 
body, where their ends are of a glaucous grayish color with a large black dot 
upon each. The legs are black and covered with short black hairs, those 
towards the tip of the forward thighs on the hind side being yellowish white. 
The wings are smoky’ brow r n and imperfectly hyaline. At the base on their 
inner side is a large lobe of a square form with its corners rounded and its in¬ 
ner edge slightly concave. The winglets are blackish and opake with a liar 
row chestnut-brown margin. 
A specimen of this same insect, sent me from west of Arkansas by William 
S. Robertson, varies in having the hairs upon the last segment of the abdomen 
much more dense, causing this segment to appear of a yellowish-white color, 
and the ends of the other segments are but obscurely tinged with gray without 
any black dot. 
From what has now been stated I think that every one will 
agree with me in the opinion that it is by this fly that the squir¬ 
rels in our country are emasculated, and that this remarkable 
