My husband started to get concerned when my dill was eaten down to a nub, so he moved a lot of the parsley worms to the parsley where they'd have more food. They didn't like it, of course. When you disturb a parsley worm, they have these little orange "tentacles" that come out of their heads and secrete some kind of foul-smelling defense chemical.
However, one had already turned into this:
Since the move, the worms have been "disappearing". I hope they haven't gotten eaten or something, and instead have also been reaching the pupa stage. The pupae camouflage so well, I'm going to be optimistic and assume they're in there somewhere about to turn into swallowtail butterflies.