This catepiller nest I thought was gypsy moth. I seem to recall masses looking like this in Virginia that I was told were gypsy moths. However, the images I found on line don't show this kind of nest thing, and the close ups of the catepillers have more colors along the back.
We get these every year, sometimes a lot of them, sometimes just a few.
They can strip a tree bare, but not always. When there are a lot of them, I will go around and pull these masses out of the trees and toss on ground.