Locate the newest mole tunnel in your yard. One way to do this is by stomping out all the mole tunnels in one day. Return to your yard early the following morning, and locate any new tunnels. These are the freshest mole tunnels.
Locate the mounds that sit on either end of the tunnel. Clear away all dirt on top of the mounds to expose the mole hole.
Put on a thick pair of garden gloves.
Insert a few calcium carbide crystals into the mole hole. Cover the hole up immediately with dirt and leave the area. The crystals will turn into a gas, filling the mole tunnels.
Repeat the process, as necessary, until your mole problem ceases.