Do you see it?
Do you see it now?
How about now?
Isn't it cool! Yes, that is indeed a tomato hornworm being parasitized by a wasp - the white things are the wasp eggs, and when the larvae hatch, they feed on the hornworm. Bwahahahahhahahaha! I love nature in action, especially when it means I don't have to squish that damn thing!
If you ever see a parasitized hornworm in your garden, do NOT kill it. Let it live, so that the wasps can reach adulthood, and go out and kill more hornworms. Natural insect control for the win!