848 
ANNUAL REPORT OF NEW YORK 
POPLAR. LEAVES. 
coarse till it reaches tho stigma, where it is widened to twice its previous thickness, forming 
a broad blue-black margin along tho inner side of tho stigma to its tip, whilst the branch 
running to the outer margin and bounding the anterior end of the stigma is much more fine 
and slender. The stigma is dull whitish and much more opake than tho rest of the wing. It 
has an elliptic outline, its length about doublo its width and slightly wider thnn the space 
forward of it between the rib-vein and the outer margin. The oblique veins are pale yel¬ 
lowish and towards their tips slightly thicker and dusky. Around the origin of the two first 
a slight duskiness is perceptible upon the inner side of the rib-vein. The first obliquo vein is 
straight. The second arises almost in contnot with it, and is straight till near its tip, where 
it perceptibly curves towards the inner margin. The third vein is abortive or invisible 
through the first fourth of its length. Tho fourth, which arises from the middle of the inner 
side of the stigma, at first slightly approaches tho third vein and then curves gently towards 
the outer margin, and at its tip bends again in tho opposite direction. Its tip is somewhat 
nearer the tip of tho third vein than this is to the second, tho tips of the first and second 
being still more distant from each other and about tho same distance that tho tip of tho 
fourth is from that of tho rib-vein. The antennm are rather thick and thread-like. Tho 
body varies in length from 0.08 to 0.10, but to the tip of the wings it is more uniform, 
measuring 0.15. These individuals are winged females, producing larva) of a pale yellow 
color. 
Galls analagous to those here described grow upon the leaf stalks of the 
Lombardy and the Black poplar in Europe, from the attacks of the Pem¬ 
phigus bursarius of Linnaeus ; but I judge our insect to be different from 
that, from specimens of the fly and its gall received from Dr. Signoret, and 
the full description of it in its different stages given by M. Fonscolomb 
(Ann. Soc. Ent., France, x, 193), the fly being paler in its color, and its 
gall spirally coiled somewhat like the shell of a snail. 
The manner in which these insects produce these galls on poplar leaves 
is described by Mr. Rennie in his Insect Architecture, and may here be 
repeated, as the process is no doubt the same in ours that it is in the Eu¬ 
ropean species. 
Often when the galls are opened a single individual is noticed therein 
much exceeding any of the others in its size and destitute of wings. This 
is the female parent from which the whole brood in each gall is descended. 
After wandering about upon the limbs and leaves during the first period of 
her life, she becomes stationary at this point on the leaf stalk, occupied first 
in erecting a house for her shelter and protection and then rearing her 
family therein. As she turns herself around, she makes a number of punc¬ 
tures in the leaf-stalk with her sharp needle-like beak. The sap which 
issues from these wounds, by its exposure to the air becomes thickened and 
curdled, whereby a thick fleshy wall of a living vegetable substance grows 
up around her, intermediate in its texture as in its situation between the 
wood and the leaf, being softer than the former and harder than the latter. 
And by puncturing this at its summit, a further exudation of the sap occurs, 
whereby the wall closes together over her, thus forming a little globe the 
size of a pea, within which the insect is securely sheltered from birds and 
predaceous insects. If in want of food sho has only to insert her beak in 
the side of her cell and suck therefrom the nourishment she requires. Her 
eggs are next strewed around upon the inner surface of this gall, although 
the cavity has only sufficient space to contain them and tho parent. But 
