Problem with our maple trees
we live in a wooded area on the flat river with mixed oak and maple trees. At least two of our maple trees have areas of bark missing, and are apparently infested. See photos... At about chest high, the bark has separated from the tree do that an area about 9 inches x 12 inches has no bark. We don't see anything moving in there. These photos are of an area of bark easily removed. The last photo is one of a couple puff ball yellowish areas still attached to the tree.
Kent County Michigan
This could be a fungus caused by a beetle. I am going to give you a few websites that explain this . I hope they prove helpful to you. Canr.msu.edu search maple diseases, extension.umn.edu, extension.umn.edu.