Caterpillar Just Laying There

I found one small monarch caterpillar and brought it home on a leaf with the wet paper towels. It was about a quarter inch long or less and doubled in size, eating around the edge of the leaf and another hole and edge around another leaf. I cleaned and replaced the damp paper towels and put in new milkweed leaves. All of a sudden last night it just lays there and isn't eating any more. This has gone on for about 18 hours.

Do you think it has died or could it be getting ready for the first of the five sheddings of its skin. I'm worried about it but am not sure what to make of it.

Would this be what happens when it gets ready to shed?

Karen says:
Yes, before the caterpillar molts it usually is still for quite a while. Give it a little more time. If it gets to be a couple of days, then maybe it has a virus or something and has died. Then, be sure and clean any containers, etc. that you used for the caterpillar with a 20% beach solution. Also, if the milkweed is from your garden that you fed it and the caterpillar dies, then you might want to try immersing any milkweed that you feed any new caterpillars in 10% bleach solution for 20 minutes and then rinse with plain water in case there are virus spores, etc. on it. Hope this helps.