Damage Prevention and Control Methods

Exclusion

Eastern Mole (Scalopus aquaticus)

For small areas, such as seed beds, install a 24-inch (61-cm) roll sheet metal or hardware cloth fence. Place the fence at the ground surface and bury it to a depth of at least 12 inches (30 cm), bent out at a 90^o angle (Fig. 5).

Figure 5. Mole fence.

Cultural Methods

In practice, packing the soil with a roller or reducing soil moisture may reduce a habitat’s attractiveness to moles. Packing may even kill moles if done in the early morning or late evening.

Milky-spore disease is a satisfactory natural control for certain white grubs, one of the mole’s major food sources. It may take several years, however, for the milky-spore disease to become established. Treatments are most effective when they are made on a community-wide basis. The spore dust can be applied at a rate of 2 pounds per acre (2.3 kg/ha) and in spots 5 to 10 feet (1.5 to 3m) apart (1 level teaspoon [4 g] per spot). If you wish to try discouraging moles by beginning a control program for white grubs, contact your local extension agent for recommended procedures.

Because moles feed largely on insects and worms, the use of certain insecticides may reduce their food supply, causing them to leave the area. However, before doing so, they may increase their digging in search of food, possibly increasing damage to turf or garden areas. Check local sources of insecticides for controlling grubs. Follow the label instructions for use.

Frightening

Some electronic, magnetic, and vibrational devices have been promoted as being effective in frightening or repelling moles. None, however, have been proven effective.

Repellents

EPA has registered several castor-oil products for repelling moles. However, these repellents are not registered in all states. Check with your local extension office to determine repellents that are available. Borders of marigolds may repel moles from gardens, although this method has not been scientifically tested.

Toxicants

Since moles normally do not consume grain, toxic grain baits are seldom effective. Ready-to-use grain baits containing zinc phosphide are sold at nurseries or garden supply stores. Two other active ingredients, bromethalin and warfarin, show promise because of their formulations. Talpirid®, is formulated to resemble an earthworm, the mole's natural food. Several warfarin-based products are formulated as gels that are injected into the burrows and either consumed directly or while grooming by moles. No reports concerning the efficacy of these product have been published to date.

Elshoff and Dudderar at Michigan State University reported on the use of Orco Mole Bait®, a chlorophacinone pellet which is used in Washington and some other states under 24(c) permits for mole damage control. Even though the researchers stated the use of this toxicant is a highly effective, and was easily applied, there are disadvantages. Two or more successive treatments are often required. An average of 21 1/2 days was required to achieve zero damage on treated dry soil, and 39 days on treated irrigated soils.

Fumigants

Two fumigants, aluminum phosphide and gas cartridges, are federally registered for use against moles (see Supplies and Materials). Aluminum phosphide is a Restricted Use Pesticide. These fumigants have the greatest effectiveness when the materials are placed in the mole’s deep burrows or runways. Golf course owners, however, report that moles can be repelled from surface tunnels by placing aluminum phosphide pellets in them. Since state pesticide registrations vary, check with your local extension or USDA-APHIS-Wildlife Services office for information on toxicants and repellents that are legal in your area. Care should be taken when using chemicals. Read and follow label instructions when using toxicants and fumigants. Many of these products can only be used by certified pesticide applicators.

Trapping

Figure 6. Mole traps: (a) Out O’ Sight^® (scissor-jawed), (b) Victor^® (harpoon), and (c) Nash^® (choker loop).

Trapping is the most successful and practical method of getting rid of moles. There are several mole traps on the market. Each, if properly handled, will give good results. The traps are set over a depressed portion of the surface tunnel. As a mole moves through the tunnel, it pushes upward on the depressed tunnel roof and trips the broad trigger pan of the trap.

The a brand names of the more common traps are: Victor^® mole trap, Out O’ Sight^®, and Nash^® (choker loop) mole trap (Fig. 6). The Victor^® trap has sharp spikes that impale the mole when the spikes are driven into the ground by the spring. The Out O’ Sight^® trap has scissor-like jaws that close firmly across the runway, one pair on either side of the trigger pan. The Nash^® trap has a choker loop that tightens around the mole’s body. Others include the Easy-Set Mole Eliminator^®, Cinch^® mole trap, and the Death-Klutch^® gopher trap.

These traps are well suited to moles because the mole springs them when following its natural instinct to reopen obstructed passageways. Success or failure in the use of these devices depends largely on the operator’s knowledge of the mole’s habits and of the trap mechanism.

Figure 7. A network of mole runways in a yard. The arrowheads (s) indicate good locations to set traps. Avoid the twisting surface ridges and do not place traps on top of mounds.

To set a trap properly, select a place in the surface runway where there is evidence of fresh mole activity and where the burrow runs in a straight line (Fig. 7). Dig out a portion of the burrow, locate the tunnel, and replace the soil, packing it firmly where the trigger pan will rest (Fig. 8).

Figure 8a. Excavation of a mole tunnel is the first step in setting a mole trap. Figure 8b. Replace the soil loosely in the excavation.

To set the harpoon or impaling-type trap, raise the spring, set the safety catch, and push the supporting spikes into the ground, one on either side of the runway (Fig. 9). The trigger pan should just touch the earth where the soil is packed down. Release the safety catch and allow the impaling spike to be forced down into the ground by the spring. This will allow the spike to penetrate the burrow when the trap is sprung later. Set the trap and leave it. Do not tread on or disturb any other portion of the mole’s runway.

Figure 9. Set the harpoon-type trap directly over the runway so that its supporting stakes straddle the runway and its spikes go into the runway.

To set a scissor-jawed trap, dig out a portion of a straight surface runway, and repack it with fine soil. Set the trap and secure it by a safety hook with its jaws forced into the ground. It should straddle the runway (Fig. 10a) until the trigger pan touches the packed soil between the jaws. The points of the jaws are set about 1 inch (2.5 cm) below the mole’s runway and the trigger pan should rest on the portion as previously described. Care should be taken to see that the trap is in line with the runway so the mole will have to pass directly between the jaws. In heavy clay soils be sure to cut a path for the jaws (Fig. 10b) so they can close quickly. The jaws of this trap are rather short, so be sure the soil on the top of the mole run is low enough to bring the trap down nearer to the actual burrow. Set the triggers on both traps so that they will spring easily (Fig. 11). Remember to release the safety hook before releasing the trap. Be careful when handling these traps.

To set a choker trap, use a garden trowel to make an excavation across the tunnel. Make it a little deeper than the tunnel and just the width of the trap. Note the exact direction of the tunnel from the open ends, and place the set trap so that its loop encircles this course (Fig. 12). Block the excavated section with loose, damp soil from which all gravel and debris have been removed. Pack the soil firmly underneath the trigger pan with your fingers and settle the trap so that the trigger rests snugly on the built-up soil.

Finally, fill the trap hole with enough loose soil to cover the trap level with the trigger pan and to exclude all light from the mole burrow. If a trap fails to catch a mole after 2 days, it can mean the mole has changed its habits, the runway was disturbed too much, the trap was improperly set, or the trap was detected by the mole. In any event, move the trap to a new location.

Figure 12. The choker loop trap is set so that the loop encircles the mole’s runway.

If one cares to take the time, moles can be caught alive. Examine tunnels early in the morning or evening where fresh burrowing operations have been noted. Quietly approach the area where the earth is being heaved up. Quickly strike a spade into the ridge behind the mole and throw the animal out onto the surface. A mole occasionally can be driven to the surface by flooding a runway system with water from a hose or ditch. Another method is to bury a 3-pound (1.4-kg) coffee can or a wide-mouth quart (0.95 l) glass jar in the path of the mole and cover the top of the burrow with a board (Fig. 13).

Figure 13. A mole can be live-captured in a pit trap. Be sure to use a board or other object to shut out all light. Cave in the runway just in front of the jar on both sides.

Other Methods

Nearly everyone has heard of a sure-fire home remedy for controlling moles. In theory, various materials placed in mole tunnels cause moles to die or at least leave the area. Such cures suggest placing broken bottles, ground glass, razor blades, thorny rose branches, bleaches, various petroleum products, sheep dip, household lye, chewing gum, and even human hair in the tunnel. These techniques do not work, and several have detrimental environmental effects. Other remedies include mole wheels, pop bottles, windmills, bleach bottles with wind vents placed on sticks, and similar gadgets. Though colorful and sometimes decorative, these gadgets add nothing to our arsenal of effective mole control methods.

Another cure-all is the so-called mole plant or caper spurge (Euphorbia latharis). Advertisers claim that when planted frequently throughout the lawn and flower beds, such plants supposedly act as living mole repellents. No known research supports this claim. Castor beans are also supposed to repel moles. Caution must be used, however, since castor beans are poisonous to humans. Several electromagnetic devices or “repellers” have been marketed for the control of rats, mice, gophers, moles, ants, termites, and various other pests. Laboratory tests have not proven these devices to be effective. Unfortunately, there are no short cuts or magic wands when controlling moles.

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