They look very healthy, I'm sure they're probably preparing to molt, probably the last one that makes the chrysalis! I say that, because, as I recall, when they're green, black and yellow (actually I think I see a little blue) without any orange stripes, it's the last instar.

Congrats, congrats!!

Sherry

Well, they look just awesome! You are doing well with them. They do look to be 4th or 5th instar to me too. It would be time to place a couple of thin sticks inside for them to attach themselves to. Just before they pupate, they will purge their guts, and you will see what looks like a pile of diarrhea in the container. They will also stop eating and begin to crawl around a lot. It's like they go on a purpose filled walkabout trying to find a place to attach to for pupation.
Angie