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California Oak Galls

Wasps in the family Cynipidae are gall inducers on plants, or inquilines of gall inducers (living inside the galls made by other cynipids). The majority of species occur on oak trees (Quercus sp.). Galls range in size from 1 mm to 6 cm or more and come in many shapes and colors, as depicted on this page. Different cynipid species occur on specific oak species, and the galls themselves occur on specific locations on the trees (leaves, stems, buds, roots, etc.) depending on the species and which generation it is. Some species have two generations per year, a sexual and an asexual (female only) generation, each producing completely different types of galls on different parts of the host. The adult wasps are generally around 1-4mm in size. The wasps support a community of other insects that feed on them, their parasites, and their galls.

Regarding the generic names I'm using on this web site, please read this page.

See also the undescribed or unknown oak gall page.

White oak group: Quercus berberidifolia (inland scrub oak), Q. cornelius-mulleri (Muller's oak; desert scrub oak), Q. douglasii (blue oak), Q. dumosa (Nuttall's scrub oak) Q. durata (leather oak), Q. engelmannii (Engelmann oak), Q. garryana (Oregon oak), Q. john-tuckeri (Tucker's oak), Q. lobata (valley oak):

Andricus albobalani
Andricus atrimentus
Asexual, fall generation
Andricus atrimentus
Bisexual, spring generation
Andricus bakkeri
Andricus brunneus
Andricus confertus
Andricus coortus
(syn: Callirhytis coortus)
Andricus chrysolepidicola
Andricus crystallinus
Andricus discularis
Andricus fullawayi
Andricus gigas
Andricus kingi
Andricus opertus
Andricus parmula
Andricus pattersonae
Andricus pedicellatus
Andricus quercuscalifornicus
Andricus stellaris
Andricus stellulus
Andricus wiltzae
Antron douglasii
Asexual, fall generation
(syn: Cynips douglasii)
Antron douglasii
Bisexual, spring generation
(syn: Cynips douglasii)
Antron quercusechinus
(syn: Cynips quercusechinus)
Besbicus conspicuus
(syn: Cynips conspicuus)
Besbicus heldae
(syn: Cynips heldae)
Besbicus maculosus
(syn: Cynips maculosus)
Besbicus mirabilis
(syn: Cynips mirabilis)
Besbicus multipunctatus
(syn: Cynips multipunctata)
Burnettweldia conalis
Burnettweldia corallina
Burnettweldia plumbella
Burnettweldia washingtonensis
Disholcaspis canescens
Disholcaspis eldoradensis
Disholcaspis mamillana
Disholcaspis mellifica
Disholcaspis prehensa
Disholcaspis simulata
Neuroterus fragilis
Neuroterus saltatorius
Asexual, fall generation
Neuroterus saltatorius
Bisexual, spring generation
Neuroterus washingtonensis
Phylloteras cupella
Sphaeroteras trimaculosum
(syn: Atrusca trimaculosa)
Trichoteras tubifaciens
(syn: Andricus tubifaciens)
Xanthoteras clavuloides
(syn: Atrusca clavuloides)
Xanthoteras teres
(syn: Trigonapsis teres)

Red (black) oak group: Quercus agrifolia (coast live oak), Q. kelloggii (California black oak), Q. wislizeni (interior live oak):
Callirhytis apicalis
(syn: Andricus apicalis)
Callirhytis carmelensis
(syn: Andricus carmelensis)
Callirhytis congregata
(syn: Andricus congregata)
Callirhytis eldoradensis
Callirhytis perdens
(syn: Andricus perdens)
Callirhytis perfoveata
(syn: Andricus perfoveata)
Callirhytis quercusagrifoliae
Asexual, summer generation
(syn: Andricus quercusagrifoliae)
Callirhytis quercuspomiformis
Asexual, summer generation
(syn: Amphibolips quercuspomiformis)
Callirhytis quercuspomiformis
Bisexual, spring generation
(syn: Amphibolips quercuspomiformis)
Callirhytis quercussuttoni
(syn: Andricus quercussuttoni)
Callirhytis serricornis
Asexual, summer generation
(syn: Andricus serricornis)
Callirhytis serricornis
Sexual, spring generation
(syn: Andricus serricornis)
Dryocosmus dubiosus
Asexual, fall generation
Dryocosmus dubiosus
Bisexual, spring generation
Dryocosmus minusculus
Melikaiella flora
Asexual, summer generation
Melikaiella flora
Bisexual, spring generation

Intermediate or golden oak group: Quercus chrysolepis (canyon live oak), Q. palmeri (Palmer's oak), Q. vacciniifolia (huckleberry oak):
Andricus chrysobalani
Andricus projectus
Disholandricus chrysolepidis
Disholandricus lasius
Disholandricus reniformis
Disholandricus truckeensis
Dryocosmus asymmetricus
Grahamstoneia humboldti
Heteroecus dasydactyli
Heteroecus flavens
Heteroecus lyoni
Heteroecus melanoderma
Heteroecus malus
Heteroecus pacificus
Asexual, fall generation
Heteroecus pacificus
Bisexual, spring generation
Heteroecus sanctaeclarae
Heteroecus sp.
Paracraspis guadaloupensis
(syn: Acraspis guadaloupensis)
Paracraspis insolens
(syn: Acraspis insolens)
Paracraspis patelloides
(syn: Acraspis patelloides)
Protobalandricus spectabilis
Trichoteras burnetti
(syn: Andricus burnetti)
Trichoteras coquilletti
(syn: Andricus coquilletti)
Trichoteras frondeum
(syn: Andricus frondeum)
Trichoteras perfulvum
Trichoteras vacciniifoliae
(syn: Andricus vacciniifoliae)

Non-native oaks growing in California: Quercus virginiana (southern live oak)
Andricus quercuslanigera
This gall has been seen on Q. virginiana in Manteca, Stockton, Brentwood, and Sacramento. It has also been seen in Los Angeles County.

For more information about California galls, see Ron Russo's Plant Galls of the Western United States (2021), an update to and expansion of Ron's 2006 Field Guide to Plant Galls of California and Other Western States.