Hummingbird and Butterfly Gardening: DAILY PICTURES #108, 2 by C_A_Ivy

C_A_Ivy wrote:
Last week I had a Black swallowtail oviposting on a few fennel plants. I collected a small piece of fennel with an egg and placed it in an aquarium which I use for rearing. I would of had two eggs but one fell and was lost during transfer.
A week later I noticed a small brownish cat and a dark prickly one. Is the prickly one a cat or molted exoskeleton ? The next day I saw only a dark caterpillar (pic 3). Since it was an early instar I didn.t recognize it until I did some image searching. Cats can sure differ from molt to molt.
Since it is on fennel, I wondering if it can be switched to parsley if necessary ?