We keep looking on the larger swamp milkweed, but haven't found caterpillars or cocoons on it yet. Hopefully, we will find the chrysalis for one of these guys and can put it in a box to watch the butterfly emerge. This plant is shaded by the larger butterfly plant, so I think we'll move it to a spot with more consistent sun for next year.
Milkweed beetles also adore the tropical milkweed plant, especially the seed pods. According to BugGuide.net, there are many species of milkweed beetles. The tropical milkweed is an annual in our climate, but we can save the seeds and start them in the spring. Dick is enlarging the garden to add more native plants next year.