My caterpillar has gotten fatter than when I left for the weekend on Friday. He has now made frass and molted. There is yellow stuff on the tissue paper, I wonder why it's there? My teacher's caterpillar is ready to turn into a chrysalis, soon! The way you tell if your caterpillar is getting ready to turn into a chrysalis, is check to see if it is in a J shape. I'm really happy with my caterpillar!