Mottled Acorn Gall Wasp

Andricus carmelensis

Cynipidae

Callirhytis

Quercus agrifolia

California

Quercus kelloggii

Oregon

Quercus parvula

Quercus wislizeni

Cynipid Galls of the Pacific Slope

Callirhytis carmelensis (agamic)

**CALLIRHYTIS CARMELENSIS**, new species

**Host:** *Quercus agrifolia* Nee and *Quercus wislizeni* A. de Candolle.

**Gall:** The gall is ellipsoidal, often laterally compressed, measuring 5 by 7 mm. It forms by the side of small acorns (approximately 4 mm in diameter), pushing out between the acorn and its cup, aborting the acorn. When growing in April, the galls are fleshy, greenish, smooth, and secrete honeydew at the apex. They drop in May, and as they harden and shrink, a raised transverse band develops near the basal end, which becomes truncate or excavated. The larval cell inside is large and transversely placed.

**Habitat:** The type locality is Monterey, California, where galls were collected on *Q. agrifolia* on August 14, 1916. Flies emerged on March 27, April 10, and April 18, 1918. Galls collected at Los Gatos on May 13, 1918, produced one fly on April 10, 1919, and another on April 11, 1920. Three living flies were cut out on November 7, 1920. Galls collected at Carpinteria on April 29, 1918, yielded flies on March 27 and April 18, 1919. A *Q. wislizeni* gall collected at Santa Margarita contained a living fly cut out on December 1, indicating transformation occurs in fall, though emergence is not until spring.

Other localities where these galls have been observed on *Q. agrifolia* include:
- San Gabriel Canyon (San Gabriel Mountains)
- Cahuenga Pass (Santa Monica Mountains)
- Fillmore, Carpinteria, Santa Barbara, Paso Robles, Paraiso Springs, Palo Alto
- Hills back of Berkeley and St. Helena

They have been found on *Q. wislizeni* at Los Gatos, Mount Tamalpais, St. Helena, and Bagby. All localities are in California.

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Notes on American Gallflies of the Family Cynipidae Producing Galls on Acorns: With Descriptions of New Species

Callirhytis carmelensis 

Quercus agrifolia, wislizeni
Acorn galls
Fig 49. "Pip" gall beside small acorn. Apr.

Fig 49. A "pip" gall on aborted acorns of previous season. Develop in April; secrete honey dew; drop in May. From galls collected Aug. 14, 1916 adults emerged Apr. 10-18, 1919 (Monterey). Collected May 15, 1918 adults emerged Apr. 10, 1919, Apr. 11, 1920 and others were cut out Nov. 7, 1920 (Los Gatos). 

Callirhytis carmelensis 

This cynipid wasp induces glossy, mottled galls at the base of acorns of coast live and interior live oaks. I have not found them on California black oaks, even though they are recorded as occurring on this species. 

They are maroon or green with light-colored mottling, and each has a small nipple at the apex. 

Galls produce honeydew that attracts ants, bees, and yellow jackets. 

Plant Galls of the Western United States

A similar gall was observed on Quercus parvula shrevei in California in [October](https://www.inaturalist.org/observations/61625893).