Won't work by me, the rats are bigger than some housecats I have seen. I feed them regularly, and they love the blue blocks so much, they eat them within hours. The people next door sat one day with a pellet gun, and picked off around 100 in a weekend. Note, I work near the harbour, where they feed on bulk meal and such. They had a humane trap, but the snake park stopped taking the rats, they were biting the snakes.