I would love for him to pupate, but at this point I fear he is dying...He has stopped eating, but is still moving some. Is this something that usually happens before the pupate stage? Is there a good site to read about all of this?

Thanks to everyone for all the great help!!!

Here's an article about rearing caterpillars. Caterpillars stop eating before they pupate. They also may stop eating when they're sick. I'm sorry I can't help you tell the difference in this current case.

Sometimes they travel a long way to find a good place to hang, so be aware that yours may disappear and turn up somewhere else unless you confine it to some kind of cage with suitable "furniture."

I am happy to say that he became super active last night, and that he is indeed confined to an aquarium with a poinsettia. I have hopes that he is getting ready to pupate, and had a lot of trouble locating him this morning. Everything I have read on the internet seems to lean towards him pupating on the leaf debris and or soil, so i should be able to spot him there. I am still a little worried about him getting out, but he is also confined to my spare bathroom at the moment. My cats thought him fun to look at too, and I did not want that to go bad! Hopefully I will be sending great pictures of him in the pupa stage soon!
Thanks again for all the help.

That's good news. Covering the terrarium with a lid that lets air through will keep him in. I have moth caterpillars in a fishtank with a homemade lid, window screen in a wooden frame. If you don't have access to tools, you can tape a piece of open-weave cloth onto the sides.

These photos and captions show various setups.

This would be Erinnyis ello, this find really makes me want to go out to the nearest nursery and check all the poinsettias!

It's funny because I was just out the other day and was thinking about the possibility of finding this species on the poinsettias that I've seen for sale, I disregarded the fact, but now I think I'll have to look more carefully in the future.