When Mole Hills Become Mountains
Bob Stewart
stewart@gardenright.info

An adult mole only weighs four ounces, and an average population density is only three to five moles per acre, and yet these small furry creatures can incite rage and despair in gardeners and defy all and every attempt to neutralize their activities. Scalopus aquaticus is the eastern mole and the primary culprit among the dozen or some mole species found in North America. Although similar in appearance to mice, moles are classified as insectivores, and are more closely related to shrews and bats than to rodents. They eat meat, primarily in the form of insects, spiders, and earthworms. In this aspect of their lives they could be considered beneficial to gardeners, since they destroy a number of important soil insect pests. However, it's how they obtain their food that's at the bottom of their constant dispute with gardeners. Moles dig blindly through the soil and eat whenever they happen upon food. They have a very high metabolism and must eat a lot, often an amount of food equal to their body weight each day. To eat that much they have to find a lot of food and that means a lot of digging. In average garden or lawn soil a mole can dig at the rate of 12 to 15 feet per hour. The tunnels moles dig in search of food are just below the surface and the digging of these tunnels severs plant roots and causes grass and other plants to decline. In addition to their surface feeding tunnels moles also dig deeper tunnels, called runways, in which they make their nests and travel throughout their territory. The soil excavated from these runways are deposited on the surface in the form of mounds of loose soil called mole hills. An active mole or two can lay waste to a well tended lawn or garden in short order. In the long run their digging may actually improve the soil but in the short term they cause ugly, serpentine yellowing of the grass, ground that sinks as you walk over it, and the loss of prized perennials and bulbs.


A life underground has it's rewards and moles have few natural enemies. The gardener and landscaper have tried desperately to be a potent mole enemy but have seemingly failed in every attempt. Such a failing record however has not been due to lack of trying. Over the years we have thrown everything at the mole, probably including the kitchen sink. Listed below, with a bit of tongue and cheek narration, are some of the control measures than have been tried.

*Poison baits: These are generally uneaten because the mole is a carnivore and doesn't care for peanuts, the most often used bait.

*Tunnel flooding: Moles can run fast and have many escape routes. In nature however floods are a major mole killer.

*Tunnel gassing with cartridges and mower engine exhaust attachments:   The soil absorbs gasses relatively quickly and the mole tunnel complex is so extensive there is always an escape route.

*Moth balls in tunnels: Moles avoid treated tunnel and dig new ones, remember 15 feet of new tunnel in one hour!

*Soil vibrating devices, pin wheels and ultra-sonic types:   Any strange smell or vibration may initially scare or irritate the mole but they quickly adapt and if your yard is where the food's at, they'll be back, and soon.

*Mole repelling plants: These plants only affect a small area, the root zone of the plant and would have to be planted in large number throughout the yard to be really effective.

*Traps utilizing knife blades and harpoons:   These are the most consistent control measures but they take time and practice to use properly. Most traps are placed in feeding tunnels, where they won't catch anything, rather than runways)

*Live Traps (same as above)

*Killing soil insects in an effort to remove food supply:   Controlling beetle grubs has been a standard mole control recommendation for years but in most yards there is usually enough non grub food remaining to keep mole happy. If anyone's interested I have a copy of a study that examined the stomach contents of 100 moles to find out exactly what they were eating.

*Shooting: You've got to be very good and usually it's not legal.

*Chewing gum in tunnel: Moles don't chew, remember they're carnivores not bubble gummers; how juicy fruit gum got to be a mole control is a funny story but basically was a hoax that caught on.

*Crushed glass in tunnel: Moles aren't that stupid.

*Gasoline in hole followed by lit match: I hope YOU are not that stupid.

*Stepping on tunnels: This doesn't get rid of moles but alleviates their damage.

*Wire barriers: Moles can't get through, but usually, you end up fencing the moles IN the yard.)

*The Pitch Fork Method: Moles can be killed by conducting a mole watch, but it is prone  to accidents and such activity can frighten the neighbors and small children.

*Cats and dogs: Can be very successful but entirely depends on the nature of the pet. Some cats and some dogs are great molers, others could care less.

*The Pet Inevitability Phenomenon: Have the kids name the mole, fall in love with the mole, and within a short time the mole will run into the road and get hit by a car. This seems statistically to work as well as the other. :-)

*Others: Please list your mole control idea. I'm always on the lookout for new ideas to thwart the mole.

I'll end with a note about castor oil extract or Mole-Med. Castor oil does seem to be a repellent to moles and it can be applied in liquid form over a large enough area to be practical. The problem is in it's residual qualities, which seem very limited. Two or three rains seem to negate the beneficial effect of the castor oil. Obviously the hope is that when the moles leave the area the first time they will take up residence in another yard and stay there, but there no guarantee this is going to happen and the moles will usually return to the original yard. The most consistent control method continues to be trapping. This can be developed into almost an art form.

Tom Schmidt is probably the world's foremost mole catcher, in fact he's known as "The Mole Man." He'll teach you how to catch moles with his video "Moles Make Lousy Pets." Video available from: The Mole Man, 2533 Orland Ave, Cincinnati Ohio 45211, (513)662-3017. I understand that this professionally produced video, with 50 minutes runtime, is also sold on several online locations for about $55. ppd.

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