I have wharf rats here I am at the water they grow half the size of a muskrat that is about the size hole they make her I sprinkle lye in thier runs they lick it off their feet and bleed out ,I trap them with M'rat sized conibear type traps, I also use foothold traps large enough to act as bodygrips SLS number 1 1/2, I also turn the pump on now and then and shoot them with a pellet rifle I will hit about a month to a month and a half I will not see them move at all the secret is not to let up when this happens