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 opertus

Quercus douglasii, dumosa, durata, garryana, lobata
Stem galls, bud galls
Cell different and adult different from above

Andricus fimbrialis

Quercus douglasii, dumosa, lobata
Leaf galls, integral
Fig 114. Globular, dia 2 mm, in young leaf.

Fig 114. in early spring. Adults emerged in May (Palo Alto).

ANDRICUS FIMBRIALIS, new species

Host. — Quercus dumosa, douglasii, lobata.

Gall (fig. 16). — Globular, green, 2 mm. in diameter, produced at side of midrib of young leaves in early spring, stunting the development of the leaf, whose blade is much reduced, its margin prominently fimbriate.

Habitat. — The type is selected from galls collected on Q. dumosa May 3, 1922, along Pierce Mill Road, near Palo Alto, Calif., the adults emerging: May 10. Flies were emerging at Lakeport May 27. Three paratypes are from galls on Q. douglasii: two from galls collected at Paraiso Springs May 9, 1918, date of emergence not recorded, and one from Paso Robles, the fly emerging May 23, 191S. One paratype is from a gall on Q. lobata collected on May 20, 1922, the fly out and dead before May 27. The galls were seen on Q. durata also. In addition to the localities given above, the galls were also seen at Boulevard, in Santa Ana Mountains, on Santa Catalina Island, Camp Baldy, Bagby, Newhall, Santa Margarita, Jolon, Los Gatos. St. Helena, Calistoga, Ukiah. Bartlett Springs, Oroville, Red Bluff. Shasta, and Baird, Calif.

Andricus opertus

This cynipid wasp induces small, monothalamous galls on the tips of new spring leaves of scrub, leather, blue, and valley oaks. These are the galls of the bisexual generation formerly known as A. fimbrialis.

Hosts:
Quercus berberidifolia
Quercus durata
Quercus douglasii
Quercus lobata

[Photo caption]
Spring gall of Andricus opertus on Oregon oak.