Thanks, Ann and Ive! Ive, if you run out of food and don't want to buy more plants, I've used the organic parsley from Publix with success. You have to feed them a lot of it since the nutrition starts to decline as soon as you pick any plant, but at least it didn't kill them.
It does seem like the Swallowtails have finally decided to show up in numbers! And just in time for the rainy season.