Polyphemus Moth caterpillar

Same caterpillar as my previous spotting, a few hours later. I was carrying it around in an open paper bag until I could get home and find a better enclosure, but it started building its cocoon in there! (I think. Possibly only a temporary shelter? I don't know their habits.). It used silk to attach a leaf to a corner of the bag. I cut out that part of the bag, very carefully, and taped it up with the same orientation inside this provisional enclosure. The caterpillar was still at work the last time I checked. I'm going to leave it outside in a sheltered area until spring, so that the changes in temperature give it the cues it needs to cocoon and emerge at the right time. I hope I get to see its transformation into a gorgeous Polyphemus Moth!