Andricus stellulus

Distinctive star-headed gall. Never protruding to the opposite surface, mature galls are typically associated with a brown necrosis around the point of attachment which extends laterally to the leaf-blade margin.

Pedicellate, monothalamous, occurring singly (infrequently clumped) on either dorsal or ventral surface. Exterior of stalk rugose, delicately reticulate to glabrous on disc; green with occasional red and yellow markings when fresh, brown or black at maturity. Disc: four to six points around perimeter, supported by slender stalk, reticulate with fine striations radiating from central darkened spot on upper surface; varies from ovoid to cupped in profile; centrally supported on stalk. Attached to leaf-blade vein by slightly enlarged basal ring. Galls usually stand upright on leaf surface.

Host:
Quercus dumosa

Quercus dumosa
Leaf galls, detachable
Like a star-headed tack, erect, on upper surface, 5-7 mm long. Fig 101.

Fig 101. On Q: dumosa. From Santa Catalina Island in March. Never reared.

Andricus stellulus

This cynipid wasp induces stalked, cuplike, monothalamous galls on leaves of Nuttall's scrub oak and shrub live oak, but for the latter host, only in the southwestern Mojave Desert near Twentynine Palms, California.

There may be some delay with the onset of gall formation to avoid the extremes of summer, or simply two cycles for this wasp: one pulse of gall growth in spring and a second in fall, as both old and fresh galls have been seen in November in the southern Mojave Desert, California.

Hosts:
Quercus dumosa
Quercus turbinella

Feron stellulum (Burnett, 1974) comb. nov.

Gall (Fig. 371). Leaf gall. Monolocular and can be found on both sides of the leaves. Disk shaped (1.6-2.3 mm in diameter) with some points around the perimeter but erected on a long and slender pedicel, usually slightly broadening towards apex. The gall is almost twice as high as the diameter of the disk (2.3–5.6 mm in height). The surface is shiny and glabrous of a reddish colour, the pedicel is crimson, and the disk is rufous. Galls are found attached either to a secondary vein of the leaf blade or occasionally to the midrib, mature galls are typically associated with a brown necrosis around the point of attachment which extends laterally to the leaf-blade margin. Emergence holes made by the gall wasp are usually found in the lateral part of the gall disc (Burnett 1974).

Biology. Only the asexual generation is known, inducing galls on Q. dumosa (section Quercus, subsection Dumosae); adults start to emerge from February.

Distribution. USA: CA.