We just moved into a new (for us) house last summer, and one of the things we've realized since we moved in, is about this tree. It's a huge tree about 3-4 feet from the house, which we're told was there before the house was built next to it. The problem is that moles or some other kind of "critter" has dug in under the tree apparently killing some of the roots and hollowing out under some of the trunk of the tree. We put moth balls in the hole to chase away the "critters" and we've filled the hole with rocks, but is there more we should do? We were told by some to fill it in with concrete and not only would that stop the decay, but it would keep the critters from going back in and help to stabilize the tree in case that became a problem in later years. Is this true? We would like to save the tree if possible since it is so big. One tree trimming company told us that if we had the tree taken down we could ultimately have foundation problems when the roots underground start to rot and soften. So now we're not sure what to do with it or about it. (The house is about 20 years old so the tree is for sure 20 years and plus some since it was there when the house was built). And I think it's a Post Oak tree.