Galls, Diseases, and Pests - Andricus albobalani Wasp
Andricus albobalani
These galls occur on the inside of an acorn shell. The acorns are usually stunted or misshapen, and they do not fall from the tree. There can be one or two galls inside the acorn.
You can see the gall on the right side of the acorn.
Here the larva is visible inside the gall.
This acorn and gall are much drier.
You can see the empty gall on the right side of the acorn.
On the top of this acorn, you can see the exit holes where the wasps exited the gall.