PA Gobbler,

Are you seeing Gypsy Moth caterpillars or Tent caterpillars?
(I'm not saying that you can't identify them , I just ran into this with my dad in Schuylkill Co.........my neice had a bunch in a cup and they were Tent caterpillars. He insisted they were gypsy moths

I'll post a couple pictures of their nests / egg casings and the mature caterpillars for comparison:

First is the Gypsy moth egg casings: