Now that the weather has turned hostile to insects and other arthropods, it's time to empty my folder of stuff to post. I collected a number of caterpillars this fall and have a box of moist potting soil that has the resulting pupae. Some I identified and some not. Here's one that I couldn't decipher.
The second one I saw crawling down a red maple and coaxed into a box. It spun a cocoon in some maple leaves I provided.
The major danger to collected pupae is dehydration. I check the potting soil weekly and keep a damp paper towel on top of the soil. The Polyphemus is in a separate (vented) container. After puzzling over the humidity issue I placed an ordinary kitchen sponge in the container. I keep the sponge wet but not drippy. Time will tell.