I hope you don't mind my asking in your thread but I'm in the same boat. I've never experienced fostering Monarch Caterpillars. I have two who are also getting ready to emerge. They turned black and I can barely see the markings inside their chrysalis.
Do I understand they need to remain in their container about 24 hrs before releasing them? I will put a couple of sticks in their container for them to climb on if needed (24 quart clear plastic storage box) and should I place a vase with some nectar blooms in there for them, too? Seems like they'd need something to eat within 24 hrs. I have the Mexican sunflower blooming and the butterflies love to nectar from it's flowers. I could pick a couple of those, check for insects and use it for the nectar source.
Thanks, NancyB, for asking this question. I came to the forum this morning to ask the very same thing.