Galls, Diseases, and Pests - Irregular Spindle Gall Wasp
Andricus chrysolepidicola
These galls form on the stems of oaks.
They are found on Blue Oak (Quercus douglasii).
It took me two years to find one of these galls that wasn't old and abandoned. This photo was taken in September 2021.
This is the same gall about a month later in October 2021.
You can see some exit holes and a bigger hole that was likely made by a bird. Gall tissue is usually high in nutrient value and is often seen as a food source. Or the bird could have just been looking for larvae!
This gall also appears to have been been pecked at by a bird or other wildlife.
I thought the pattern of exit holes on this was was interesting.