816 
ANNUAL REPOUT OK NEW YORK 
OAK. LEAVES. 
perceptible difference between them is that one grows upon the leaves and 
the other upon the twigs. And the other flies in the glass boing found of tho 
parasitic hind, he would perceive they must have subsisted on and destroyed 
other individuals of these gall makers, and had thus come out of the galls 
in their stead. Thus, where he supposed he had simply one vegetable pro¬ 
duction from which a single kind of insect would come, he finds nature has 
actually formed two of the former and four of the latter. With such 
astonishing profusion and seeming superabundance is every little corner 
and recess in the domain of nature diversified and teeming with life. 
Internally in these little masses of wool are numerous hard seeds about 
the size of grains of wheat, of a bright chestnut color, crowded together 
and attached by their lower ends to the vein of the leaf. In each of these 
is a worm, which, on completing its transformations, gnaws off the upper 
end of its cell, and eats directly outward through the wool and escapes 
from its confinement, hereby making the same pin-hole perforations in these 
soft wooly galls that are seen in the other harder kinds when the insects 
have evacuated them. 
I have not succeeded in obtaining the males of this species, its galls 
having in all but one instance yielded me parasites only. This is the more 
remarkable, since, from the very similar galls of the wool-sower growing 
on the twigs, I have never obtained any insects of this kind. And it would 
hence appear that the one gall being firmly fixed whilst the other vibrates 
and swings with the leaf, nature has left the multiplication of the one to bo 
cheeked by the birds, and they being unable to pick into the other, these 
parasitic destroyers have here been formed and commissioned to execute 
the same work. 
Like most of the other parasites which infest this group, these pertain 
to the family Ciialcididaj, belonging to the same order of insects with 
the gall-flies. They may bo named and distinguished as follows : 
The Oak-wool parasite, Spalangia Querci-lanai, now species. 
Black, with the face, antennae, sides of the collar, and legs whitish or 
greenish-yellow. Length 0.08 to 0.10. Some individuals have the upper 
side of the hind thighs and of the first joint of the antennae black. The 
abdomen is smooth and polished, its under side of a tawny red color, and 
it is separated from the thorax by a pedicel. The stigma of its fore wings 
is a semicircular black shining spot with a small appendage on the inner side 
of its hind end and its base slightly separated from the robust rib-vein, which 
vein is of a dark brown or black color. Its cubical head, which is about 
as long as wide, indicates its relationship to Spalangia, though in some 
other respects it does not appear to fully coincide with the characters 
assigned to this genus. 
Specimens frequently occur, so very different in their colors that they 
might almost be deemed a distinct species. They maybe termed the Lino- 
backed variety ( dorsalis) of the Oak-wool parasite. In them the thorax 
