Cynips quercus juglans n. sp. [gall only]

QUERCUS ALBA. White Oak? Large, round gall of a hard corky substance, growing on the branches; a round, hollow space in the center. Diameter 0.75-0.95.

I found a couple of these galls in winter, on the ground, under an oak, the species of which I was unable to ascertain. Afterwards, Mr. Hitz, of the Maryland Agricultural College, communicated to me a number of these galls, with the statement that they grow on the branches of the white oak. All these galls, as well as those found by myself, were somewhat shrunken and wrinkled on the surface, probably from the effects of dryness. They are easily distinguished from the galls of C q. globulus Fitch by their large size and their much harder substance. It requires some effort to cut them open, whereas, the dry galls of C. q. globulus can be easily cracked. For the same reason the kernel of the latter gall can be more easily detached from the surrounding corky substance, than that of the other gall. The greater part of the galls which I cut open contained a cluster of small evidently parasitical larvae. In two or three, however, I found a single Cynipideous larva. I did not succeed in rearing it, but obtained several kinds of parasites.

Amphibolips prunus

Quercus coccinea, ilicifolia, imbricaria, nigra, palustris, rubra, velutina
Acorn galls
A plum gall produced on the side of the acorn cup in the fall, dropping when mature and becoming wrinkled.

Quercus falcata
Acorn galls
A plum gall in eastern and northern states, 13-19 mm in dia, wrinkles in drying.

[Photo caption]
On Q velutina. Also on Q coccinea, rubra, palustris, imbricaria, ilicifolia, falcata, nigra. Transformation takes place in the fall; emergence in the spring Feb 17-May 14 MO and is distributed over more than one season. Galls contain the highest percent of tannin (40%) of any that have been analysed but fluctuates from year to year.

Amphibolips prunus [new name]

I found last August and early in September, in very great numbers both on Q. rubra and Q. tinctoria, growing on the side of the cup of the acorn, a globular, smooth, plum-like, fleshy, intensely bitter gall, about .50-.75 inch in diameter, mottled with yellowish and crimson outside, and internally yellowish in the centre and towards the circumference pink like a watermelon. This gall, of which I forwarded a specimen to Baron Osten Sacken, is thought by him to be identical with his Q. juglans, which was described only from dry, shrivelled-up specimens, and which was stated by Mr. Hitz who found it "to grow on the branches of the White Oak," (Q. alba.) a species that belongs to the first section of Quercus. Either Mr. Hitz must have been mistaken, both as to the tree and the part of the tree on which he found Q. juglans O. S., or else my gall is a distinct species. If so, I propose for it the name of Q. prunus. It is the only N. A. Cynipidous gall known so far to grow on the acorn, though, judging from the names, the European Cynipidous galls, q. calicis and q. baccarum, grow the one on the cup of the acorn, like Q. prunus, and the other on the acorn itself.

Amphibolips prunus

Cynips quercus prunus

This is the well known oak plum gall which grows on the acorn cups of red oak (Q. rubra), black oak (Q. velutina), scarlet oak (Q. coccinea), and scrub oak (Q. nana [ilicifolia]). It is bright red, more or less globular and often looking like a marble. When fresh it is solid but fleshy and of a pink color inside, shading into yellow toward the middle, where there is a single large larval chamber. When mature it becomes blood red and when old and dry it becomes shriveled and quite hard. It matures late in August or early September, and the fly emerges the following spring.

Amphibolips prunus

Cynips quercus juglans
Cynips juglans
Cynips quercus prunus

Gall. On acorn cups of red oak (Quercus rubra), scrub oak (Quercus nana [ilicifolia]), quercitron oak (Quercus velutina) and scarlet oak (Quercus cocinea) in August and September. Bright red, more or less globular, smooth, and sometimes looking almost like a marble. When fresh it is solid but fleshy and of a pink color inside, shading into yellow toward the middle, where there is a single large larval chamber. Subsequently it becomes mature and it turns blood red, and when old and dry it becomes so hard as to be cut with difficulty. Diameter 15 to 25 mm.

Habitat: New England and Middle States, south to GA, and west to CO.