And the rugosa:

I had a few canes afflicted by a rose stem girdler look like that. I cut off the afflicted rugosa branches. The bushes look fine now. I plan to burn the canes that were afflicted.

Thanks both of you. I’m not exactly sure what I’m looking for, but I haven’t seen any of the signs of physical damage I read about in some googling — either entry holes from cane borers, or tunnels inside the canes from borers/girdlers (I clipped a couple canes off to look inside). My understanding is that there should be some telltale signs of damage with either of these pests. Is that right?

Another thing I notice looking closely at the rugosa is that there are a few new green shoots coming out of canes where everything else had previously wilted. I’m not sure whether that’s to be expected with girdlers or borers?

I’m pretty new to rose pests, and haven’t had any trouble with the rugosa before, so please excuse my ignorance. I appreciate all the info.

I did not take photos sadly, but my rose girdled canes had a slight swelling on the cane where the invasion occurred. It looked like the snake swallowing a rodent photos, with a bulge along the cane and the distal end dead after the swelling.

Hmm. I don’t see any suspicious bulges on the roses.

Then it might be a borer like mad gallica said. My borer holes are visible sometimes here, but some go in a sunburned spot and aren't as obvious like in the flat head apple borer damage cases. The cane just wilts and if I cut it off, I can find a worm in the cane. Very sad.