They're ugly, they're yukky, and they'll eat the leaves of a branch. Other than that, they're harmless. They will not kill your tree, even if they completely strip it (which they won't.) I have them in my pecan trees as we speak and I hardly ever do anything about it.
But if you just can't stand them and don't want to nuke 'em, do as my grandfather did. Cut the branch off and burn it. (If you can't burn it, haul it off somewhere.)
When you prune a tree, take the branch all the way back to a fork, to where it comes off a larger branch, or to the trunk. "Tipping" branches invites disease and/or insect infestation, whereas correct pruning will heal itself.
Be sure your fingers are not in the way when you prune.