Thanks for the replies, everyone, and apologies for my delay in follow-up. Life got a bit insane. I've looked at zillions of photos of Geometridae and Noctuidae and so far haven't come up with a match. Whatever it was, I now kind of wish I'd preserved it so that it could metamorphosize... ah well. @Renee & York Rose: Perhaps the bug people are vacationing, but it does seem odd - I'll just keep waiting patiently. I did find a couple more affected-looking buds and pruned them away but did not find another caterpillar to photograph. If I do, I'll take 300 photos if necessary to get a few good in-focus photos from all angles. (That'll also help me learn how to work the camera settings heh..) At this point, it appears that pruning out the infested-with-whatever-it was sections has solved the problem, and I have tons of new growth that so far looks healthy as a result, so I will hold off on the Bt and keep a close eye on everything. Other than the obvious damage from Japanese Beetles, which I continue to drown in soapy water, the only damage now seems to be the older damage from the rose slugs. I currently have 4 blooms which, while smaller than usual, all look normal. So, I'm so glad I didn't freak out & remove the whole rosebush! Thank you all so much! The next thing I need to do is some pruning. I think I mentioned in the other thread that I had been holding off due to a praying mantis egg case. Either this mantis egg case opened already where I can't see the opening, or maybe it's just not going to - seems like it should have by now. I have found baby mantises in 2 other areas of the yard, but none around this bush, so I know hatchings have occurred... I guess I'll just keep that little section of cane somewhere after pruning, as I'm pretty sure the mantis who laid this did so rather late in the fall. Anyway, once I get him all shaped nicely I'll take new pics! Bella Roma - saved from destruction!

The two that most resemble the photograph that i have found are the Striped Garden Caterpillar (specifically includes Milkweed among the caterpillars food plants) and the other would be the Yellow Striped Armyworm (Spodoptera ornithogalli). There is a photograph in Wagner's CATERPILLARS OF EASTERN NORTH AMERICA that is very close...about as identical as you can get. Good luck in your search! Bob

Looks like it might be an armyworm to me.

There are two caterpillars. In the second picture, it’s not a shadow. Do they walk out of their skin growing? I have no idea, but that what it looked like. A pile of discarded clothes. I check on them every day. Always getting nervous if I don’t see them at first. Wonder if these were the eggs.