Andricus opertus (sexgen)

Feron dumosae (sexgen)

Neuroterus washingtonensis (sexgen)

Neuroterus washingtonensis (agamic)

Andricus opertus (agamic)

Disholcaspis eldoradensis (sexgen)

Disholcaspis eldoradensis (agamic)

Bassettia ligni (agamic)

Bassettia ligni (sexgen)

Feron pattersonae (agamic)

Andricus opertus
Bisexual generation

Andricus fimbrialis Weld, new synonymy

[Photos of this gall appear on page 4 of the pdf]

Galls: Galls appear as reddish swellings on the midrib of the leaf, mostly on the upper surface when the leaf is about three-quarters grown. Soft fimbriate dark red spines soon develop, usually growing diagonally away from the leaf base. Galls vary from single ovate cells, about 2 mm long, with little swelling or spinulation, to several cells over most of the leaf length, with individual gall length up to 15 mm; on young terminal growth, the whole stunted leaf may be utilized. Galls are most common on small slow-growing trees, but also occur on larger more robust trees. Often many galls are restricted to a few trees which are apparently the same as other, uninfested trees in the same area. Adults emerge amid the spines of the gall, leaving a fuzzy pale-brown mass of chewed fiber at the exit holes. Leaves with dead galls usually fall with the other leaves. 

Range: from southern Oregon to central California

Adults of the bisexual generation emerge during late May through July. Oviposition occurs within 5 days in the small lateral buds on new growth. Galls and immature adults are fully formed by mid-September

Andricus pattersonae 
Bisexual generation

[Photos of this gall appear on page 12 of the pdf]

On the margins of young leaves, occasionally submarginally, more frequently on the basal section of the leaf, rarely on the leaf stem; more commonly on the lower leaves of small trees. Individual galls about 3x1 mm, eccentrically fusiform-ellipsoidal, apex attenuated and curved; the surface densely micro-spinose. Immature galls pale green, maturing to dark red. Single monothalamous, but sometimes in groups of 2-4, possibly 8 or 9 on a leaf. Emergence hole is at the upper end of the gall, below the apex. Parasitized galls are often more globular and variable in size, usually brighter red. 

Range: west-central CA

Adults of the bisexual generation emerge during late May to early June, and females oviposit on the undersides of leaves. Galls that are too crowded develop at an uneven rate and many do not mature. The agamic females may emerge the following spring, late March to early April; however, a diapause within the gall for 1 or 2 years is common. 

Neuroterus washingtonensis, bisexual generation

[see paper for photo, figure 16 on page 11 of the pdf]

Gall. Irregular swellings on undersides of principal leaf veins, usually on young subterminal leaves; on trees of any size or age, but seldom on very young trees or next to the ground; more common in relatively open sunny exposures. The upper side of the leaf is contorted and reddish. The polythalamous galls contain from 4 to 85 cells, oriented towards the upper surface of the leaf, and vary in size from 7 to 55 mm, sometimes over the entire leaf length; they may be single, multiple or confluent. Occasionally more than one leaf is involved if the gall develops quickly on terminal growth. Many galls may occur over a relatively small area of a tree. Young galls are firm and white inside, green outside, becoming progressively paler and redder, finally becoming brown and hard after the insects have emerged. Adults emerge on the topside of the leaf in early summer, usually from individual exit holes. The galls persist long after the leaf parts weather away. 

Adults of the bisexual generation emerge during late June. The polythalamous galls usually contain both males and females. 

Neuroterus washingtonensis, agamic generation

[see paper for photo, figures 17 and 18 on page 11 of the pdf]

Hosts: Quercus garryana

Gall: Monothalamous subovoid chambers just under the bark of slender twigs; approximately 1 x 1.5 mm, somewhat conical at outer end, oriented up and out; the thin brownish shell incorporated into the soft pith. Galls may occur singly or in groups up to 8, usually at a node or just below a bud; slight swelling distortion may occur. They seldom cause any discoloration to the stem. Exit holes made by the adults are relatively small, and often involve a short tunnel obscured by chewed bark. Sometimes galls occur in sufficient quantity to stunt or kill twigs and small branches.

Agamic females chew their way out of the twigs during March and April, and oviposit on the upper vein surface of young leaves in the opening buds.

Galls of agamic N washingtonensis are frequently on the same twigs as the bud galls of agamic A opertus, or the twig galls of agamic D eldoradensis. Agamic females may oviposit in the same buds as agamic Bassettia ligni, but the much larger galls produced by the former are usually dominant.

Andricus opertus
Agamic generation

[Photos of this gall appear on page 4 of the pdf]

Callirhytis nigra
Diplolepis operta
Andricus nigridius
Andricus opertus

GALL (Figs. 3, 4). Usually completely concealed within the leaf buds, eccentric, occasionally causing minor distortion. Approximately 2.5 mm long, shape varying from flattened-ovoid to pointed-ellipsoid. The pale brown shell of the mature gall is polished and sparsely striate longitudinally. There is usually only one gall in a bud. It may be distinguished from the somewhat similar gall of Disholcaspis eldoradensis (Beutenmueller) by its earlier occurrence, smaller size and stubbier shape, generally darker color, and more striate appearance. 

Range: northern CA

Agamic females chew relatively large circular exit holes subapically on the gall and through the side of the bud during late March to mid-April. They oviposit in the opening leaf buds.

Disholcaspis eldoradensis
Bisexual generation, new description

[Photos of this gall appear on page 4 of the pdf]

GALL (Fig. 5). Bluntly pointed ellipsoid inside the bud, usually stunting it, and frequently protruding; about 3 mm long, and 1.8 mm wide sub-basally; seldom symmetrical. Very pale brown; the surface with distinct fine longitudinal reticulation. Subapical exit holes are rough-edged, subcircular, sometimes apical. Monothalamous, usually only one gall to a bud; more often in small lateral buds on slow-growing trees than on stout or terminal buds. 

Agamic females emerge during November and December and oviposit in buds at that time. Most of the gall and larval development occurs early the following spring. Adults of the bisexual generation emerge during April and May, and oviposit in the twig bark.

Disholcaspis eldoradensis
Agamic generation

[Photos of this gall appear on page 4 of the pdf]

GALL (Fig. 6). On last year's twigs in the intervals between buds, sometimes close together; usually on fast-growing relatively young trees. Galls are oriented along the twig, but seldom evenly or in rows. Number may vary from one to several dozen; relatively small numbers on robust twigs attain greater size and more perfect shape than those in large colonies on small twigs, which may be distorted by crowding; monothalamous. Circular emergence holes are usually at the ends of the galls. The hard broken shells and deep scars may remain on a tree for years; small twigs are often killed by the galls. Frequently the same tree is utilized for the agamic generation year after year, and develops a clipped stunted appearance.

Range: San Francisco area

Adults of the bisexual generation emerge during April and May, and oviposit in the twig bark. Gall colonies usually result from one female rather than from communal oviposition. First evidence of a gall is a slight swelling of the bark, which splits longitudinally as the gall develops. Very young galls are yellow, changing to green, brown, and shiny dark red by early autumn; thereafter the color becomes dull and darker. Agamic females emerge during November and December and oviposit in buds at that time. 

Bassettia ligni
Agamic generation

[Photos of this gall appear on page 6 of the pdf]

GALL (Figs. 9-1 1 ). Monothalamous cells beneath the bark, approximately 1 x3 mm (Fig. 10); single, confluent, or crowded. Crowded galls often small and irregular in form (Fig. 11). Oviposition is usually in twigs at least 2 years old, so galls and emergence holes appear on third-year growth (Fig. 9), but they may be present in 2- to 6-year growth. Single or scattered groups of galls are seldom apparent, but when a twig is heavily attacked it is slightly swollen and growth is adversely affected (Fig. 12). After the insects leave, the cells become dark in color and sometimes contain a staining fungus. Emergence holes may remain visible on the branch for several years. Galls may be on trees of any age, and often seem restricted to an individual tree within a group. 

Range: northern CA and possibly central OR

Agamic females emerge from the bark in mid-April; individual "colonies" have an average emergence span of only 5 or 6 days. They prefer calm sunny days with temperatures above 55°F to oviposit in the leaves within the swelling buds. The cream-colored eggs are elongate conic-ovoid, ca. 135X.055 mm. Dissected females contained an average of 320 eggs. The galls of the bisexual generation become visible in about 4 weeks. 

Bassettia ligni 
Bisexual generation

[Photos of this gall appear on page 6 of the pdf]

GALL (Figs. 7, 8). Inconspicuous blister-like swellings in the blade tissue of mature leaves, seldom near the margins or in the veins. Mature galls are approximately 4 mm diam., but only about 2 mm are visible on the top surface of the leaf as an indistinct subcircular swelling, slightly brown-puckered off-center. Living galls are more noticeable on the underside of the leaf where the swellings are more pronounced, slightly smoother and paler than the surrounding tissue, and with dimpled centers (Fig. 7). Adults normally emerge from the upper surface, leaving rough subcircular exit holes that soon develop elevated margins (Fig. 8). These holes become more conspicuous as the leaves die. Galls may contain 1-4 cells and are frequently confluent; polythalamous galls more often contain males. Individual leaves may have 1-30 galls. 

Adults of the bisexual generation emerge during late June to mid-July. Males wait on nearby leaves for females to emerge. Adults are most active during mid-day. Females oviposit on 2- to 5-year-old stems, often on their host tree in the areas where the agamic generation emerged earlier in the year. The pupal stage develops by September. 

Liodora pattersonae
Agamic generation

[Photos of this gall appear on page 12 of the pdf]

GALL (Fig. 15). On the underside of mature leaves, but not on principal veins or extreme margins; on trees of all ages and sizes. Single and monothalamous, usually several to a leaf, but 1-100 possible. Individual galls disc-like, thin, 3-6 mm diam., 51. mm maximum thickness at elevated midsection; finely radially striate. Pale ivory-green, occasionally dappled darker as galls mature to a tan color. Overwintering galls may fall from or with the leaves. 

Range: west-central CA

Adults of the bisexual generation emerge during late May to early June, and females oviposit on the undersides of leaves. Galls that are too crowded develop at an uneven rate and many do not mature. The agamic females may emerge the following spring, late March to early April; however, a diapause within the gall for 1 or 2 years is common. 

Alternate generations of gall cynipids (Hymenoptera: Cynipidae) on Garry oak