*Dad* was looking at my photos - which had flash. And he's looking at them larger than life on the monitor. *I* am looking at the actual hole, inside the wall. In shadow. Dad noticed something I didn't.
Yes, it's out of focus, but do you see what he saw? Here's a hint - look at the electrical wire, not the hole.
The little bastards chewed through the insulation and into the wire. That led me to go look at the other side of the stud bay.
That side is even worse. So. For a next step, we're going to move forward with the top patch, because there's nothing bad happening up there - Bob is getting everything together right now. We'll foam the hole to the outside, just to exclude the furry Visigoths (also, Great Stuff will act as an insulator for the exposed wire.) We're going to Not Screw With the wire going between the stud bays until Dad can come visit. We'll use the piece of removed drywall to cover over the hole and keep curious fingers and whiskers safe, and Dad will come help with wiring repair. When that is done, I can patch the bottom hole.
I'm kind of wondering if they weren't able to get back out because they were electrocuting themselves. But I would think that would have tripped the breaker. Who knows?
Ah - the fun of homeownership.