Feron atrimentum (Hymenoptera: Cynipidae)   (Synonym: )
Striped Volcano Gall Wasp
Mt Diablo State Park, Contra Costa County, California
May 22, 2014

Host is Quercus douglasii (blue oak). This is the spring, bisexual generation gall of this species, cut open to show radiating fibers around larval chamber.