After a few days, I noted that my milkweed plants had disappeared. I took the picture below when the mosquitoes were out in full force, so I didn't stick around to work on the outwitting the auto-focus of my camera. That blur is a stem.
All that work refrigerating the seeds and weeding and babying the plants--gone to waste! Well, actually not to waste. Here's the culprit in the photo below.
Those plants fed a very healthy monarch caterpillar. I don't know if the plants will recover, but I'm glad I did it.