Oak gall, a swelling of tissue caused by small non-stinging wasps, is a common problem encountered by many homeowners. Although the deformation looks threatening to the health of the tree it typically does little damage other than causing unpleasing aesthetics for homeowners. However, severe infection over a number of years can stress the tree and cause decline. Unfortunately, there is not much that can be done to treat oak gall. The article below addresses the basics of oak gall.