I battle the same problem, Patrick. And the past couple of years have been awful for them multiplying -- they're everywhere...........
In the Iris beds, the moles tunnel around the Irises, for the most part -- but when it rains (and it has rained a LOT) -- the tunnels collapse and take the Irises down with them so that the rhizomes become buried deep in the soil. The consequences, of course, is rot. Moles have been responsible for quite a few of my losses. I've even found their runs in the Nurserybeds, which are raised!!!
I have yet to find a viable solution for them. Arlyn uses a trap, which works well for him -- but I bought one and could not exert enough strength on it to set the trap.