I found the square box traps with a 'walk up' ramp work best by far, YMMV.

My childhood friend Andy and I used to trap lots of big mud bugs near the earth dam his granddad had on a lake he impounded himself back in the 50's. He loved us taking mud bugs from around the dam area because they burrowed into the dam face.

The first mud bug I ever ate as a boy was one Andy and I caught and boiled in a tin can right beside the lake. Can't get any fresher than that.

Tom