I didn't do it this fall, and now I'm really regretting it, cuz some rodents have moved in. I have a trap set for the rodents, but need to patch the holes so no more come in!! The guy at the hardware store says there's nothing that will work in this weather. Do I really have to wait til spring, or is there a cold weather solution?
Steel wool first, then expandable foam in a can. Give it a little blast and it will hold everything to the brick.
They never get in after that, and you sealed an insulation leak.