Andricus formosus

Quercus catesbaei [laevis], cinerea [incana], laurifolia, marilandica, phellos, texana [buckleyi], velutina
Stem galls, detachable
Fig-shaped galls in cluster on twig in spring, dropping when mature in June (DC).

[Photo caption]
On Q coccinea. Occurs on all the red oaks. Galls drop when mature in June (DC). From galls collected in 1914 adults emerged Feb 24, 1915 and Feb 15, 1916.

Cynips quercus formosa n. sp.

Quercus rubra. A cluster of forty or fifty elongate-ovate galls on a branch of a young red oak tree. They are from three-fourths of an inch to an inch in length, and a half an inch in diameter in the middle, tapering to a point at the ends; covered with a short, velvety pubescence, and when dry, ridged like a melon; the inside, a cork-like substance adhering closely to the larval cell, and divided lengthwise into many parts like the dissepiments of the seed-vessels of various kinds of plants; monothalamous - the cell one-tenth of an inch long.

The flies have not yet left the gall (Nov. 25) though they have been in the imago state for several weeks, and crawled about actively when the galls were opened. They may be imprisoned by the hard dry gall, but I am inclined to think, that, like some other species, they remain in the galls in the perfect state through the winter and come out early in the spring.

The galls of this species are very rare. I have found only two clusters, and one of these was much eaten by some Lepidopterous larva, and the larvae of the true gall fly were destroyed. Only a part of the galls in the other cluster were developed as described above; the smallest were not larger than grains of barley, but contained larvae, and have produced true gall flies. Their diminutive size was owing, apparently, to their being closely crowded.

This and the species next described, C. q. ventricosa n. sp., are readily distinguished from any other American species yet described, by the female, (male as yet unknown,) having fifteen distinct antennal joints. Dr. Fitch (N. Y. Rep. Vol. 2. No. 309) speaks of having, in his collection, a female gall fly with fifteen jointed antennae, but he does not describe it, nor the gall from which it came.

Westwood (Syn. Gen. Br. Insects) does not characterize any genus of the family Cynipidae as having more than the female 14, and the male 15 antennal joints — but the male of my C q. singularis* (Proc. Ent. Soc. Pliila. Vol. 2nd. p. 32(3) has 16-jointed antennae, and C. q. scitula — a new species described in this paper — also has the same number. The females of both these species have only 13 joints, the terminal one long and connately divided in the middle.

C. q. formosa and the species next described are evidently closely related, for besides the 15-jointed antennae of the 9 there are other points of resemblance; and the remarkable difference in the colors of the two species, the ripple-marked thorax of C. q. formosa, and the widely different galls from different species of oak, are the most marked specific characters. The shape of the abdomen of both species is peculiar; different in form, and, I think, in structure, from any other species I am acquainted with, but I have not yet sufficiently studied the structure to describe it well, and have simply, in my description, noticed the vertical diameter as equalling or exceeding the length.

Andricus quercusformosus (Bassett 1864)

Hosts: Quercus laevis

[Asexual generation detachable stem gall found in Florida in the spring.]