You have selected to post a comment about the photo shown below. Please only use this area to comment on this specific photo. If you are wanting to post your own photo of this plant, you can do so at this page over here.
Lovely photo, but I believe that is a Black Swallowtail caterpillar, not a Monarch. BST's go for the dill, parsley, fennel, rue. I just had a few BST's on my dill but the birds got them while they were right about this stage!
