When I was a teenager, we had a rat problem in our house. They chewed through 3/4 inch plywood to gain access to our warm laundry room. We came home from grocery shopping one day to see a rat sitting up in the middle of the laundry room floor, looking for all the world as if he belonged there!
Until we could get some bricks and mortar to cover the hole, we came up with a unique deterrent.......
I found one of my brother's old work socks and filled it full of red cayenne pepper. I put cayenne pepper in the rat hole and blew it back into the basement (you know, a few well-placed puffs of air). Then I stuffed the peppered sock into the hole.
Well, about 9 PM that evening, we heard the rats chewing around the entry hole. Then there was silence for a few seconds, then they started to squeal loudly and run around as if they were racing one another!
They didn't try chewing at that spot again, gave us time to use bricks and mortar to close it up!