What Is This?

When pulling into my driveway in the middle of last week, I looked into my yard and saw something small hanging in the air. At first I thought that a spider had created a huge web in the yard and caught something. However, after exiting my car and walking closer to the object I saw this: a green worm-type creature on a single thin strand that hung down from my sweet gum ball tree.

The worm was not opaque, so that is the reason none of these pictures are great pictures. The sun kept shining through the worm. It was one of the prettiest light greens I had ever seen.

As I proceeded to take photos, the worm climbed further and further up the tiny strand that was about as thick as a spider web strand. Does anyone know what this is?

While I was traipsing around the yard in my attempt to take pictures from various angles (and still never captured a good one), the usually panicky squirrel sat and ate his nut. For a change, he didn't seem bothered by me one bit.