We don't get hornworms around here, anymore. I think I saw one when I was a kid. That's about it.

However, I have some advice that would probably help:

* Put a black light on a wooden post in the middle of your tomato patch. We always had loads of cool moths when we had a bug zapper. Just ex the zapper and do the black light.

I've seen some crazy looking horn worms that won't have anything to do with tobacco or tomatoes.
They are plant specific.