Holcaspis bassetti, n. sp.

Gall: The gall occurs, sometimes singly, but usually in clusters about the twigs. The cluster represented at Fig. 2 was composed of 30 of these galls closely crowded together. The galls resemble very much the galls of Holcaspis duricoria Bass (Cynips mamma Wal) (Fig 3). The galls are very much the shape that a thick waxy material would take if dropped on the twigs and then suddenly congealed, leaved stout, test-like projections standing out from each drop. The central cell is placed low in the gall and can usually be seen protruding when the latter is broken off. Some entomologists have thought this gall to be identical with Walsh's C. mamma, but I have examined a large number of both forms and find the following points of difference, which convince me that this, if not a new species, is certainly a well marked variety:

H bassetti as compared with H duricoria, is rather larger and more irregular in outline. The teat-like projection is much heavier and longer in proportion to the size of the gall and appears to be a drawn-out portion of the substance of the gall, while in duricoria it is a small, hard pointed projection much resembling a spine in many cases, and often almost entirely wanting. In bassetti the substance of the gall is more corky and easy to cut. The central cell, as before stated, is at the base of the gall, and when the latter is removed the point of the cell can usually be seen protruding below. Before the gall is detached the central cell is situated with its greatest diameter perpendicular to the limb at the point of attachment of the gall. In duricoria the cell is situated at the center of the gall; it never protrudes from below when the gall is detached; and it always has its greatest diameter parallel with the limb at the point of attachment of the gall. The central or larval cells are also differently shaped. In duricoria the cell is egg-shaped, while in bassetti the end towards the twig is somewhat pointed, so that the cell is very much the shape of a plump apple seed with the point rounded off.

Holcaspis bassetti

Host Quercus macrocarpa

A monothalamous gall occurring singly or in clusters around the stems of the host. When grouped the galls often cover completely 4 to 5 inches of the stem.

When the gall is not deformed by crowding, it is irregularly circular in outline at the base, gradually tapering to a distinct point that is recurved in most cases. The gall is attached to the host by a small stalk at the centre of the base. Colour green, often tinged with pink when young; becoming brown when more mature. The larval chamber resembles closely that found in the former species [Disholcaspis quercusglobulus] in being oval and free at maturity, but it differs in being placed nearer the base of the gall and in tapering to a point at the end nearer the twig.

Diameter at base, average, 16 mm.

Holcaspis bassetti

Q bicolor, MI. Attenuated cone clustered on twig.

Disholcaspis bassetti

Bassett's bullet gall. Broadest at the clasping sessile base and tapering gradually above, the apex often lop-sided, 15-20 mm high, the larval cell basal. Single or in crowded clusters on twigs of trees of Q bicolor in fall. Adults emerge in early Oct.

Disholcaspis bassetti

Quercus bicolor, macrocarpa
Stem galls, detachable
Conical, sessile, clasping at the base, single or in small numbers, in fall.

[Photo caption]
On Q bicolor. Also on macrocarpa. Contained pupae Sept 16, adults Oct 2.

Disholcaspis bassetti

Galls of this species have been observed on Quercus bicolor at Evanston, Winnetka, Waukegan, and Blue Island, IL. At Evanston the galls contained pupae on September 16, and adults emerged October 3, 1915.

Brodie collected the galls on Q. macrocarpa on several occasions at Toronto. In 1886 the adults emerged November 29-December 5, in all 247 specimens, all females. In a few days several oviposited in buds, thrusting the ovipositor between fold of bud scales. None survived the winter. In 1893 adults issued November 9-23, all females.

Disholcaspis bassetti

Globose, usually with a produced, curved apex, single or clustered twig gall, green turning to brown, on Q platanoides [bicolor], Q imbricaria [mistake--likely confused with Callirhytis ventricosa].