Could, possibly, maybe be a Catalpa Sphinx, Abbot's Sphinx, or a really lost Galium Sphinx larva. What is it doing to the tomato, if anything.

I was also thinking of a Catalpa worm. Maybe it fell from a Catalpa tree nearby? I have terrible infestations but they don't eat anything besides my Catalpa tree. This is what they look like. They do have a little black horn on their butt that can't be seen in the photo.
Karyn
{{gwi:365101}}

How were the stipes arranged? Like a dark phase of the usual tobacco or tomato hornworm?

The stripes are arranged just like a tomato hornworm. It's just that it's black with yellow diagonal stripes instead of green with light green/white stripes. It was eating a tomato plant (foliage). I only have one catalpa, and it's a very small one that I planted from seed- barely 4 ft tall, and nothing has been chomping on it so far. I'll post a pic later. (gotta download it to the computer)
Mrs H

If you found it on a tomato plant, and it look just like a tomato(or tobacco) hornworm, other than the color....then it is likely a tomato or tobacco hornworm exhibiting an unusual color expression. In most parts of Texas, the Tobacco hornworm is much more common than the tomato hornworm... so that could be your guy.

Here is a link that might be useful:

It looks like the black one, so will the moth coloration be different too?
Thanks, Mrs H