Help identifying tree and identifying something on the leaves

hello, I'm not sure what this tree is so looking for some help identifying that, but my bigger problem is what are the little pods on the underneath of the leaves are and should I do something about them?
It seems to be an infestation on my poor tree and not sure if it can recover if these things are going to hatch and eat the leaves.
As you can tell there has been some munching by something on the leaves.

So the little pods start off white by being burrowed by something on the top of the leaf. It then grows and has little "hairs" on the outside of them and sometime turn purple in colour on the tip of the pod. The tree is literally covered by these things, but I've never see anything crawling on the leaves so not sure what is doing this.

Thanks for any help you can offer.
Cheers
Cliff

 

Hackberry with galls.

 

Thanks for the fast response Ron,
after looking things over on this site after your identification it looks like they don't actually harm the tree that much after all and that I just have to make sure I protect the house in September from them trying to squeeze in through the screen door...
Nothing to do to stop them again next year as it seems pretty labour intensive to control them. My tree is around 45' high so no hope in getting to the top of the tree to spray...
let nature take its course I suppose

Cheers
Cliff