If gophers are any indication, I too am sold on the Victor rat traps inside the weasel boxes. They are cheap and extremely effective. I messed with coils this summer, and had poor results, went to jumps and had much better luck. I tried the rat traps, and have had 100% behind the neck kills on the last 19 gophers. With a baited trigger staring them in the face, the feet never leave the hole, and most have been dead with their teeth still on the trigger. I can well imagine a chicken liver, or peice of muskrat wired to the trigger will be a good system. I haven't tested the concept on ermine, but I can't think of why these won't prove to be very efficient.