Phylloxera caryaeavellana

Hosts: Carya pallida, tomentosa, cordiformis, texana, glabra

Leaf gall: hazelnut [shaped]

Round and flat above; often slightly convex or sunken below leaf surface; crimson, green, or yellowish-green; diameter 5.0–10.0 mm; below globular and often with a hazelnut shape, light green, pubescent, and apex splits into several bracts at maturity.

Range: AL, AR, DE, LA, MS, OK, SC, TX

Phylloxera caryaeavellana Riley

Galls projecting underneath leaf are globular, pale greenish, like a small hazelnut (5-10 mm diam.), above leaf flat or slightly concave. Galls mature in May-June, emergent alatae have orange abdomen, BL 0.9-1.2 mm (Pergande 1904). On Carya tomentosa in Washington, D.C. The life cycle is unknown.

Phylloxera caryae-avellana

Carya sp.
Conical or globose leaf galls with distinct orifice and containing aphids
Gall flat above, walls fleshy, either flush with or sunken below the leaf surface, globular or pyriform beneath and more or less constricted at the base, with or without a distinct nipple which, when present, splits into several bracts, diameter and height 5 to 10 mm.

Phylloxera caryae-avellana Riley.

Not uncommon on the leaves of Hicoria tomentosa along the Potomac near Washington.

Judging from the appearance of the galls, as regards size, shape and color, one might be led to conclude that we had to deal with two or more distinct species. A careful study and comparison, however, of the architects in their different stages, shows but one species. The more typical, larger and more brilliantly colored galls are the product of those stem-mothers which first settled, at a time when the development of the young leaves was most rapid and the circulation of the sap most vigorous.

By the 20th of May many of the galls already contain pupae or even winged females, while others contain only eggs and larvae. By the middle of June most of the galls are already empty and by the end of the month have become dry and shrivelled.

The transverse diameter varies from 5-10 mm and the height is about the same. Flat or but slightly convex above and either flush with or somewhat sunken beneath the surface of the leaf ; sub-conical or more or less globular beneath,, constricted at base and resembling somewhat in shape a diminutive filbert. The surface beneath is quite densely pubescent and with similar minute yellow papillae as those which cover the under side of the leaves, and causing a certain stickiness. The orifice, at the top of the gall, is, before maturity, closely drawn together and densely covered on the inside with white wooly hairs, opening at maturity into several short and stout bracts. Walls very thick and succulent. The color above is either greenish, yellow-green or of a more or less intense, beautiful crimson or pink ; and beneath pale greenish, or even almost white.