Parasitic wasp gall???

Could those hairy light brown balls in the photo in my last post be parasitic wasp galls? I had never heard of galls before, but after Googling some search words about these things, I see there are hairy/fuzzy ones. I guess the wasps hatch out and then the gall falls off the leaves??? I am going to go and take a few leaves off this tree and place them in an insect house and watch them to see what happens. If anyone has any idea about them, please share!!! It is oh so interesting!!! I will post pics on any developments!

What is this?

This afternoon, the grands and daughter and I went for a nature walk and came upon this tree with these furry light brown things on the backsides of all the leaves? It put me in mind of fern spores...(I used to have a fascination with them)... At first glance you might think they are really short furry caterpillars, but then we saw tons of them all under the tree on the ground. Well, maybe someone out in blogland will know. Sorry I didn't get a pic of the tree.