Bagworm genocide

The trees outside my house are covered with these things:

They're all over the neighborhood, they've already killed one tree of mine, and they're working on the others. I'm pulling off as many as I can, but there are literally thousands of small ones. I've sprayed all the trees, and haven't seen any movement since then, so I'm reasonably confident most of them are dead. I've also fed the trees with some Bayer plant protecting stuff. So far, I think we're at a stalemate.

I want to go on the offensive. I want to wipe out this species. How do I do it? And is there any reason I shouldn't?