I have a placard in my barn with a large armamentarium of mole-discouraging and mole-destroying devices. I've not found the mothballs to work, but they're cheap and pretty non-toxic, so worth a try. I have tried gases, granules, poisoned worms, ultrasonic noisemakers,traps, and various weapons. The only really reliable way I've found is this German gun,
sold in most large French hardware stores and large garden shops--the garden shop on the other side of the roundabout from the Briconautes at the Zone Industriel du Mont, at Aubusson, carries them, and the blank cartridges it needs. It must be positioned correctly in the mole's tunnel, and secured by passing a small stake through a loop on its handle. Try to let air, but not much light, pass by the device into the tunnel. Moles always have two tunnels to each molehill, and one has the choice of guessing in which tunnel the mole is lurking or, as I do, have a gun for each tunnel. The device fires a blank, and it's the explosion, not a ball, which does in the mole. Care must be taken not to put one's hand in the way of the business end of the device, and to keep it from discharging while placing it.
There is also a French anti-mole Improvised Explosive Device, an ingenious and somewhat flimsy apparatus triggered by a small plunger attached to a capacitor which ignites a sort of wired firecracker placed in the tunnel.
One mole can look like dozens, in terms of the tearing-up of one's yard.