Rat poison. We need to do that every year. For the roof, you can just throw them there. For other areas, you may need a case so that they won't be eaten by other animals, e.g., pets, by mistakes.

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The poisons are blood thinner in a massive dose. So, the rats will bleed to death. They will just die somewhere hidden outside of the house and I have never seen a death one. For a unit or apartment, it may be problem if they are inside.