oak galls

Member of galls

galls on red oaks

live oak bud gall wasp
Callirhytis quercusagrifoliae

live oak bud gall wasp
Callirhytis quercusagrifoliae

small, green, berry-like
forms in place of buds on branches of coast live oak (Quercus agrifolia)

live oak apple gall wasp
Amphibolips quercuspomiformis

live oak apple gall wasp
Amphibolips quercuspomiformis

forms in place of buds on branches of coast live oak (Quercus agrifolia) and interior live oak (Quercus wislizeni)
different gall forms in spring vs. summer

gouty stem gall wasp
Callirhytis quercussuttoni

gouty stem gall wasp
Callirhytis quercussuttoni

forms within branches of coast live oak (Quercus agrifolia) and interior live oak (Quercus wislizeni)

pumpkin gall wasp
Dryocosmus minusculus

pumpkin gall wasp
Dryocosmus minusculus

forms on (usually upper) leaf surfaces of red oaks (section Lobatae) (specifically, the black oaks)

irregular spindle gall wasp
Andricus chrysolepidicola

irregular spindle gall wasp
Andricus chrysolepidicola

forms within branches of white oaks (section Quercus)

galls on golden oaks

ruptured twig gall wasp
Callirhytis perdens

ruptured twig gall wasp
Callirhytis perdens

forms within branches of red oaks (section Lobatae)
after the stem ruptures, the fissures turn black

other stem galls of red oaks don’t create black fissures

round leaf gall wasp
Heteroecus flavens

round leaf gall wasp
Heteroecus flavens

forms within leaves of canyon live oak (Quercus chrysolepis) and huckleberry oak

beaked spindle gall wasp
Heteroecus pacificus

beaked spindle gall wasp
Heteroecus pacificus

forms within the tips of branches of canyon live oak (Quercus chrysolepis) and huckleberry oak

golden gall wasp
Heteroecus melanoderma

golden gall wasp
Heteroecus melanoderma

wool does not easily rub off [source]
forms in place of buds on branches of canyon live oak (Quercus chrysolepis) and huckleberry oak

woolly gall wasp
Heteroecus dasydactyli

wool is longer than on golden gall wasp (Heteroecus melanoderma)

but the wool rubs off easily when rubbed, leaving a smooth surface [source]

forms in place of buds on branches of canyon live oak (Quercus chrysolepis)

galls on white oaks

california gall wasp
Andricus quercuscalifornicus

california gall wasp
Andricus quercuscalifornicus

forms on branches of white oaks (section Quercus), usually valley oak (Quercus lobata)
a large tan gall that looks similar to the fruit of california buckeye (Aesculus californica)

oak gall is attached to the side of a branch, may be on a tree with leaves, may be lumpy, has no lines on which to split
buckeye fruit hangs from the tip of a drooping twig, is typically seen only on leafless trees, and may be partially split in half to show a shiny brown layer beneath

red cone gall wasp
Feron kingi

red cone gall wasp
Feron kingi

forms on leaf surfaces of blue oak (Quercus douglasii), oregon oak (Quercus garryana), and valley oak (Quercus lobata)

round gall wasp
Burnettweldia washingtonensis

round gall wasp
Burnettweldia washingtonensis

forms on branches of california scrub oak (Quercus berberidifolia), nuttall’s scrub oak (Quercus dumosa), blue oak (Quercus douglasii), leather oak (Quercus durata var. durata), and valley oak (Quercus lobata)

beaked twig gall wasp
Burnettweldia plumbella

beaked twig gall wasp
Burnettweldia plumbella

forms in place of buds on branches of california scrub oak (Quercus berberidifolia), nuttall’s scrub oak (Quercus dumosa), blue oak (Quercus douglasii), leather oak (Quercus durata var. durata), and oregon oak (Quercus garryana)

convoluted gall wasp
Andricus confertus

convoluted gall wasp
Andricus confertus

forms on the midrib under leaves of valley oak (Quercus lobata)

fuzzy-gall wasp
Cynips conspicuus

fuzzy-gall wasp
Cynips conspicuus

forms on leaf surfaces and petioles of white oaks (section Quercus)

spined turban gall wasp
Cynips douglasii

spined turban gall wasp
Cynips douglasii

forms on leaf veins of white oaks (section Quercus)
fewer “spines” than urchin gall wasp (Cynips quercusechinus), with smooth surfaces between the spines

urchin gall wasp
Cynips quercusechinus

urchin gall wasp
Cynips quercusechinus

forms on leaf veins of white oaks (section Quercus)
more “spines” than spined turban gall wasp (Cynips douglasii), with little space between the spines

clasping twig gall wasp
Disholcaspis prehensa

clasping twig gall wasp
Disholcaspis prehensa

constricted around middle
flared base generally clasps twig at least somewhat
cap curved and pitted
forms on branches of white oaks (section Quercus)
produces honeydew, which may attract ants

honeydew gall wasp
Disholcaspis eldoradensis

smooth sides
sits on a narrow peg-like base
cap is flat or barely curved and pitted
forms on branches of white oaks (section Quercus)
produces honeydew, which may attract ants

crystalline gall wasp
Feron crystallinum

crystalline gall wasp
Feron crystallinum

forms on lower leaf surfaces of california scrub oak (Quercus berberidifolia), nuttall’s scrub oak (Quercus dumosa), blue oak (Quercus douglasii), leather oak (Quercus durata var. durata), and oregon oak (Quercus garryana)

disc gall wasp
Feron parmula

disc gall wasp
Feron parmula

forms on leaf undersurfaces of white oaks (section Quercus)

yellow wig gall wasp
Druon fullawayi

yellow wig gall wasp
Druon fullawayi

forms on leaf midribs and petioles of white oaks (section Quercus)

Feron amphorus

Feron amphorus

forms on leaves of white oaks (section Quercus), usually near the edge

galls on multiple types of oaks

live oak erineum mite
Aceria mackiei

live oak erineum mite
Aceria mackiei

forms hairy pits on lower leaf surfaces of red oaks (section Lobatae) (specifically, the live oaks) and canyon live oak (Quercus chrysolepis)

oak leaf blister
Taphrina caerulescens

oak leaf blister
Taphrina caerulescens

formers blisters on leaf surfaces of red oaks (section Lobatae) [source]

Gallformers seems to list all oaks, but that’s likely pessimistic

each strain infects a specific oak species, but the strains have not yet been taxonomically separated

24 observed taxons / 2 unobserved taxons / 1 key

Chris’s observations: 81 (65 are research grade)

Locations:

Edgewood Park & Natural Preserve: 21
Bear Creek Redwoods OSP: 6
Joseph D. Grant CP: 6
Mt. Diablo SP: 6
Coyote Valley OSP: 4
Santa Teresa CP: 4
Almaden Quicksilver CP: 3
Calero CP: 3
Sierra Azul; OSP: 3
Alum Rock Park, San Jose: 2
Desolation Wilderness: 2
Henry Coe SP: 2
Jacks Peak CP: 2
Sierra Vista OSP: 2
Skyline Ridge OSP: 2
Castle Rock SP
Coal Creek OSP
Coyote Creek Trail
Coyote Lake / Harvey Bear Ranch CP
Dr. Aurelia Reinhardt Redwood RP
Ed R. Levin CP
Hidden Villa, Los Altos Hills
Pescadero Creek CP
Picchetti Ranch OSP
Pinnacles NP
UCSC Campus Natural Reserve
Ulistac Natural Area, Santa Clara
Windy Hill OSP

Months:

Apr.: 5
May: 11
Jun.: 4
Jul.: 3
Aug.: 3
Sep.: 9
Oct.: 3
Nov.: 29
Dec.: 7
Jan.: 4
Feb.: 3

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