Not only represent holes in trees a threat to their stability, but they also diminish their appearance, which is why homeowners often want to patch them up to reconstitute the original natural aesthetic. While tree holes provide homes to birds, squirrels and pests, their internal decay can be dangerous and affect the structural integrity of the tree. Patching of a tree can reduce the spread of tree pests or prevent rain from entering the tree, which would cause further damage. Although, tree experts don’t often recommend patching of tree holes, it usually does more harm than good, as the trees become even more unstable.