Hi, I have a Mimosa Tree(w/pink flowers) that had a problem. One of the branches was invaded by Valley Carpenter Bee's for several years. The branch had to be removed today, it was falling off. When we removed it, it left a hollow area. My husband found it full of tons of rich black dirt which from what it looks like goes down into the tree completely. We left the dirt in it and wonder if this is normal for this type of tree to be hollow with dirt/decomposition etc in it. I want to keep the tree but Im worried it will be a hazard to others walking under it. Its in our front yard.