Identifying Caterpillars in My Garden

We have an all black wooly bear and one where the skin is brown with black wool. They are everywhere this year. I’ve always called them wooley bear but they lack the band that you show. Any ideas as to what I am seeing? They travel on top of the grass like a boat in water!

I used to find Caterpillars of different species in Conn.; I don't see as many caterpillars these days; or Butterflies;

I had a Citrus tree out doors, two years ago, leaves were being eaten by about five of these green caterpillars.

I live in the Piedmont of South Carolina, and I get a lot of these in my pecan trees, every year, and they eat so many leaves, that it has the tree almost bare of leaves, and ugly. And the trees are too tall to get to them. What are some ways to get rid of them? I don't want to put any "man-made" chemicals on/in the ground, so is there an organic product I could find, to use, to kill the pupa? Thanks for any help on the issue. I love learning about all these insects in my yard, especially with the pictures of them, that makes it much easier to identify them.