I'm adding this to the gallery because it shows two stages of the larval development - an earlier (third, I think) instar to the left and a later (fourth) one to the right. The dill plant was loaded with both kinds, and the next day they had all molted and looked like the one on the right. I have read that the striped warning coloration develops on later instars when they have accumulated enough chemicals from the host plant to become distasteful, and that the earlier ones are colored for better camouflage.