Moles are present in lawns due to an adequate food source. Typical food for a mole is earthworms and night crawlers. Earthworms and night crawlers are almost always present in healthy lawns. According to Purdue University extension service, the only effective method for killing moles in a lawn is through the use of a scissors or harpoon trap. Scissor traps are used for deep tunnels, while harpoon traps are placed near the surface. Chemical baits are available, but pets may dig up the enticing bait and consume the poison.
Stomp all visible mole tunnels flat with your feet. This will aid in identifying the main tunnel the mole uses for traveling out from its den. Wait until the next morning for tunnels that have been reestablished.
Identify the main mole tunnel. Generally, the straightest tunnel will be the main travel area for the underground mammal.
Set the harpoon trap according to the manufacturers directions. There are many varieties of harpoon traps and each manufacturer may have slight modifications to the trap's spring-loaded mechanism. Typically, the trap is set above the tunnel, at the surface. The two support legs will straddle the surface and tunnel. Push the legs into the soil. Pull back on the top spring mechanism--this will cause the trip lever to lock into place. The harpoon trap is now set.
Dig the lower end of the scissor trap into the tunnel, using the shovel or hand trowel, if you are using this type of trap. Most scissor traps need to be placed in the ground, in the main path of the mole's tunnel. Use the scissor trap in tunnels that run well below the surface. Identification of the tunnels may be more difficult. Set the trap according to the manufacturers directions.
Open the surface tunnel carefully with the hand trowel to place the poison bait into the center of the main travel area. You may wish to wear a pair of rubber gloves to keep your scent from the bait, and to also protect yourself from the poison. Carefully place the removed soil from the tunnel back over the bait.
Check the traps or baited area the next morning, or if one of the two types of traps have been tripped. Reset the traps if no mole has been captured. It may take several attempts, in setting the traps and laying the bait, to kill the moles in the lawn.