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.

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. lobata (valley oak):
Andricus atrimentus Asexual, fall generation	Andricus atrimentus Bisexual, spring generation	Andricus brunneus	Andricus confertus	Andricus crystallinus
Andricus fullawayi	Andricus gigas	Andricus kingi	Andricus opertus	Andricus parmula
Andricus quercuscalifornicus	Andricus stellaris	Andricus stellulus	Andricus wiltzae	Antron douglasii
Antron quercusechinus	Besbicus conspicuus	Besbicus mirabilis	Besbicus multipunctatus	Disholcaspis canescens
Disholcaspis corallina	Disholcaspis eldoradensis	Disholcaspis mellifica	Disholcaspis plumbella	Disholcaspis prehensa
Disholcaspis simulata	Disholcaspis washingtonensis	Dros pedicillatum	Liodora pattersonae	Neuroterus saltatorius
Phylloteras cupella	Sphaeroteras trimaculosum	Pink Bow Tie Gall Wasp	Leaf Gall Wasp	Xanthoteras clavuloides
Xanthoteras teres

Black oak group: Quercus agrifolia (coast live oak), Q. kelloggii (California black oak), Q. wislizenii (interior live oak):
Callirhytis congregata	Callirhytis flora Asexual, summer generation	Callirhytis flora Bisexual, spring generation	Callirhytis perdens	Callirhytis quercusagrifoliae Asexual, summer generation
Callirhytis quercuspomiformis Asexual, summer generation	Callirhytis quercuspomiformis Bisexual, spring generation	Callirhytis quercussuttoni	Callirhytis serricornis	Dryocosmus dubiosus Asexual, fall generation
Dryocosmus dubiosus Bisexual, spring generation	Dryocosmus minusculus

Intermediate or golden oak group: Quercus chrysolepis (canyon live oak), Q. palmeri (Palmer's oak), Q. vacciniifolia (huckleberry oak):
Andricus lasius	Andricus projectus	Andricus reniformis	Club Vein Gall Wasp	Disholcaspis chrysolepidis
Dryocosmus asymmetricus	Heteroecus dasydactyli	Heteroecus flavens	Heteroecus lyoni	Heteroecus melanoderma
Heteroecus pacificus	Heteroecus sanctaeclarae	Heteroecus sp.	Paracraspis guadaloupensis	Trichoteras burnetti
Trichoteras coquilletti	Trichoteras vacciniifoliae

Non-native oaks growing in California: Quercus virginiana (southern live oak)

Andricus laniger This gall has been seen on Q. virginiana in Manteca and Stockton.