If the strychnine bait didn’t work the zinc phosphide will be less effective. Trapping works , but is time consuming. The old fashioned traps work well just don’t let them close on you when setting. There is what is called a black hole trap that looks like a short piece of three inch plastic pipe. It seems to work better than most. Another method that works is to take the exhaust of an older gas engine and pipe it down the hole. The carbon monoxide will kill anything in the hole. Good luck.