Dryocosmus dubiosus (Hymenoptera: Cynipidae)
Two-horned Gall Wasp
Knowland Park, Oakland, Alameda County, California
April 16, 2007

On Quercus agrifolia (coast live oak). This is the spring bisexual generation of the wasp; the galls develop in the catkins. Notice the exit hole in the gall in the lower right of the cluster.