806 
ANNUAL REPORT OF NEW YORK 
OAK. L1MB9. 
first half of its length and then uniting with the margin to beyond the mid¬ 
dle, where it is slightly incurved and ends in an irregular triangular knob. 
309. Oak-tumor gall-fly, Cynips Quercus-tuber, new species. (Hymenoptera. 
Cyniphid®.) 
On or near the ends of the small limhs and twigs of the white oak, hard 
irregular swellings thrice as thick as the twig below them, the bark upon 
them of a brighter cherry red color than elsewhere, and their substance in¬ 
ternally corky and woody ; produced by the stings of a small black gall-fly 
with dull pale yellow antennae, mouth and legs, its hind shanks and its 
antennae towards their tips being dusky, its length 0.08 and to the tips of 
its wings 0.13. 
These tumors or galls are quite common, particularly upon the soft and 
tender limbs of small young trees. Two distinct varieties in their form 
will be observed as they grow at the ends of the limbs, or lower 
down upon their sides. Those upon or near the tips of the limbs 
are shorter routided galls, little longer than broad, and usually of 
a deeper red color and a more irregular uneven surface. They are 
about a half inch in length and a fourth less in thickness. Those 
growing along the side of the stem are longer elliptic galls of about 
the same width as the preceding, but twice or three times as long, 
and of a paler though still a deep cherry red color. The whole 
circumference of the limb is involved in this diseased swelling, ex¬ 
cept a narrow stripe along its hind side where the bark retains its 
natural striated appearance. When fully grown the surface of both 
kinds of these galls becomes glaucous white, as though thinly coated 
with moldiness. Sometimes two, three or more of these tumors 
occur on the same limb, placed irregularly one below the other, or running 
partially into each other. A single one, however, always suffices to kill 
the limb at and above the point where it is situated, thus arresting its 
onward growth until one of the lateral shoots below grows to become a 
leading shoot in place of the one thus destroyed. 
On cutting into these galls the small limb on which they grow is found 
to have its wood thickened or swollen, and over it, forming the chief bulk 
of the tumor, is a corky substance of a yellowish brown or snuff color, 
between which and the wood are several small hard grains resembling 
seeds, each having a cavity in its center, in which, doubled together, lies a 
soft white footless worm or maggot. This, on completing its growth, 
changes to a pupa in the same cell, and subsequently to a fly like its par¬ 
ent above described ; whereupon, to escape from its confinement, it gnaws 
out of this hard seed-like envelope and onward through the corky sub¬ 
stance and the external bark, thus producing those small perforations like 
pin-holes, which are always seen in these tumors after the insects have 
made their exit therefrom. 
As several kinds of galls and gall insects are to be noticed in this part 
