What are the little white things on my caterpillar our caterpillar keeps getting little white sacks all over its body?

Hey!

I was looking for this answer myself. I don't know if these are caterpillars on your tomato plants (that is what I am experiencing), but according to the site referenced below, these white sacks are the pupae of the Braconid Wasp. The Braconid Wasp is a natural predator of hornworms (my type of caterpillar). Apparently, the wasp lays its eggs in the prey, and when the eggs hatch into larvae, they begin eating the hornworm's organs. The white sacks are actually the cocoons from which the wasps will emerge.

Even though the caterpillar was eating my tomato plants, I feel really bad for it. I might put it out of its misery. I can't imagine something eating my insides when I'm alive!

Source:
http:/www.tammysrecipes.com/tomato_hornworms