Update: By early April there were still two caterpillars on my Lime citrus tree. On 3 April I watched one crawl down from the tree, across the path and attach to the stem of an Azalea to begin pupation. (Pupation may have been arrested due to the rain we received around this time. A week later I found it on the ground and only part way through the process. Have brought it inside but not sure it will complete its transformation.) As of 17 April the second is still in caterpillar form but must be nearly ready to pupate. As with the Orchard Swallowtails, I would think this is very late for this butterfly.