What in the world are these strange string-like things all over my neighborhood? (details inside)

This is really hard to describe, so I hope that someone will have some idea of what it might be. I tried to get photos, but it’s too difficult to photograph.

There are very fine looking strings all over the sky in my neighborhood. It looks almost like someone has run fishing line in every direction and tied it off blocks away. Some are 15–20 feet off of the ground, and I saw others reflecting in trees that are probably 60 feet tall. Most of them appear to have no distinct beginning or end, but some of them seem to span over several blocks in the sky. I have been seeing them off and on for the last couple of months, but today I found 4 in my yard. Or, rather, above my yard/house. At first I thought that they might be related to the phone lines, but that doesn’t explain why there are grids of them in trees that are dozens of feet taller than the phone poles.

Then, today, I saw a strange item seemingly blowing in the sky and it looked like a streamer. I thought it might be some kind of kite, so I took a walk around the block and find that it’s a large piece of ribbon or plastic about 10 feet long and it is suspended 25 feet in the air on one of these strings. I followed the lowest one in my yard and it ended at the telephone pole in front of my house. It appeared to be tangled around the wires and hanging down, and it looked… rubbery. Or stretchy. Thin and clear and strong, but not like fishing twine.

Seriously. What the hell is it? I really can’t come up with a rational explanation for what it could be.