Monarchs not to worry- We've got ya "covered" in Pennsylvania

This is one of my outdoor group, found three on this plant late afternoon yesterday.

This is two groups I've brought indoors (2 cats to each)
Don't know if I'll wanna keep up with the indoor groups and may put them back outside, but protected. For now, they're in my bedroom with the door closed so the kitty doesn't mess with them. When I was a kid there were plenty of Cecropia caterpillars around and I always brought them inside for the duration, but they stayed put, and didn't travel around like Monarchs. Have any of you out there done this with Monarch cats, or other type cats? which ones? Indoor or outdoor? Any tips to share?