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California Oak Galls Induced by Unknown or Undescribed Species

There are many undescribed cynipid wasps in California. Some of their galls have been known for decades -- over 60 years -- but the wasps have never been scientifically described.

In some cases, adults have never been reared from their galls, which is why they haven't been described. Adults are needed for scientific descriptions of new insects. In other cases, adults have been reared but are awaiting experts to describe them as new species, or perhaps describe them as alternate generations of already described species.

Alternate generations usually make completely different types of galls, at different times of the year, often on different parts of the tree (ie., buds versus leaves), even though the wasps are the same species. So it can be difficult to make the connection between the two generations.

Since oak galls don't cause significant economic damage, there is little incentive to fund cynipid research in the U.S., and many cynipid species in California remain unknown.

See also the page of scientifically described oak galls.

-- Thanks to Diane Erwin for her help creating these pages. --

Intermediate or golden oak group: Quercus chrysolepis (canyon live oak), Q. palmeri (Palmer's oak), Q. vacciniifolia (huckleberry oak):
Gall type #1
Q. chrysolepis, vacciniifolia
Gall type #2
Q. chrysolepis, palmeri, vacciniifolia
Gall type #3
Q. chrysolepis
Gall type #4
Q. chrysolepis
Gall type #5
Q. chrysolepis
Gall type #6
Q. chrysolepis
Gall type #7
Q. chrysolepis
Gall type #8
Q. chrysolepis
Gall type #9
Q. chrysolepis, palmeri
Gall type #10
Q. chrysolepis, vacciniifolia
Gall type #11
Q. chrysolepis
Gall type #12
Q. chrysolepis
Gall type #13
Q. chrysolepis
Gall type #14
Q. chrysolepis
Gall type #15
Q. chrysolepis, vacciniifolia
Gall type #16
Q. chrysolepis
Gall type #17
Q. vacciniifolia, chrysolepis
Gall type #18
Q. vacciniifolia
Gall type #19
Q. palmeri
Gall type #20
Q. palmeri
Gall type #21
Q. palmeri
Gall type #22
Q. palmeri
Gall type #23
Q. palmeri

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):

Gall type #100
Q. garryana
Gall type #102
Q. garryana
Gall type #103
Q. douglasii
Gall type #104
Q. lobata
Gall type #105
Q. lobata
Gall type #106
Q. berberidifolia
Gall type #107
Q. cornelius-mulleri, berberidifolia
Gall type #108
Q. durata, berberidifolia

For more information about California galls, see the Field Guide to Plant Galls of California and Other Western States by Ronald Russo.