Annie,
You are doing good bringing them inside if your weather is going to get bad.
Looks like a monarch caterpillar. Can't see the tubercles from the photo too well...but two sets means monarch, three sets means queen.
How big are they? They look small in the photo. Perhaps a second instar stage. They might be molting into the next instar if they are not eating and crawling around.
Last instar monarch caterpillars get close to two inches in length and probably a tad thicker than a crayon when they are ready to form a chrysalis.
They might not like the dampness of paper towels though. Try laying just a few fresh leaves on the bottom of the cage and change them out daily or more often if they eat them up fast. Be careful with the paper towels...some of the smaller caterpillars can crawl around and get lost in the folds and can't figure their way out.
I prefer to use shallow dish or block of wet floral foam set on a piece of foil or a jar lid. I stick my larval host plant cuttings or leaves into that. The plant stem stays moist and cuttings or leaves stay fresh for a few days before they start to dry out and need to be replaced.
Read through the sticky thread at the top of this forum. Lots of excellent information on raising caterpillars that saves repeating about cat cages, cleaning, larval host plants etc. :o)
Keep us posted on their progress too :o) We all love photos!!!
~ Cat
