I went out to the front one evening to look at the clouds as a storm as blowing in. As I was walking back up the path to front door, I could hear this weird crunching noise, like something chewing. I walked over to one of our two trees in the yard and noticed that 2 big branches were just skeletons! The leaves were all gone!
I ran in and got Wade so he could take a look and grabbed my iPad to look up what they were. They are Contracted Datana and apparently they just eat until they are finished and then move on to another tree. There was no suggestion on what to do, so Wade cut the branches that contained the worms (they were in giant clusters!), and we put them in a bucket of scalding water with a drop of dish soap (to remove the surface tension). They all drowned.
A month later and they still have not returned.