Moles

Overview

Although moles are the bane of many lawn owners, they make a positive contribution to the health of the landscape. Their extensive tunneling and mound building mixes soil nutrients and improves soil aeration and drainage. Moles also eat many lawn and garden pests, including crane fly larvae and slugs. Their main food is earthworms and grubs, but they will also feed on isopods and small amounts of vegetable matter.

Moles spend almost their entire lives underground. They have small, weak eyes; small hips for turning around in tight places; and velvety fur that is reversible to make backing up easy. Moles also have broad front feet, the toes of which terminate in stout claws faced outward for digging.

Moles have broad front feet, with claws that face outward for digging. The Chehalis Indians in Washington State use a word that translates as "hands turned backward" for moles.

Two species of moles, the hairy-tailed and the star-nosed, occur in Maine. The hairy-tailed mole, found primarily along the western border of Maine, prefers loose, well-drained, sandy loam soils. The star-nosed mole, found throughout the state, lives in low, wet ground near bodies of water, swamps, wet meadows, and wet spots in fields and low-lying woods. It prefers wet, mucky humus. An excellent swimmer, it has been found under the ice of streams and ponds as well as foraging in bottom sediments of wetlands. It usually lives in small colonies. Its bizarre, star-shaped nose tentacles may be capable of detecting slight electrical fields emitted by aquatic prey.

A Profile of Moles

  • Minute eyes are often not visible.
  • The muzzle is long and tapering.
  • The many small teeth do not show.
  • The soil plug is located in the middle of the mound, but it may not be distinct.
  • Tunnels are often just beneath the surface, leaving a raised ridge of mounded ground.

Facts about Maine's Moles

Territory

  • Moles do not share burrows.
  • Except for females with young, moles are solitary animals that live in established burrow systems with limited overlap into the territories of other moles.
  • The ranges of neighboring females may overlap.
  • The range of a male may overlap those of a number of females, but the ranges of males do not overlap.
  • Population densities vary from one adult per six acres to more than five adults per acre.
  • The average city lot will rarely harbor more than one male or two females.

Food and Feeding Habits

  • Moles will sometimes eat a small amount of vegetation, but are mostly insectivorous.
  • The diet includes earthworms, centipedes, millipedes, snails, slugs, grubs, ants, sowbugs, beetles and crickets. Star-nose moles eat aquatic invertebrates as well.
  • Moles patrol their complex arrangement of tunnels in search of prey that use the tunnels or fall into them by accident.

Nest Sites and Reproduction

  • Depending on the species, moles will mate from late March through early May, and produce a single litter of three to five young.
  • The nest is constructed from soft vegetation that is matted down and interwoven to form a compact, protective shell about two inches thick. The nest is located within a cavity five to 18 inches underground, usually in "high ground" to prevent the next from being flooded by the rains of late winter or early spring.
  • Green vegetation may be added to the nest after the young are born. As the wet plant material decays, it generates heat that keeps the young warm when their mother is absent.
  • Young moles disperse above ground at night during the month after weaning, forming their own territories within about 30 yards of their birth site.
  • Moles reach sexual maturity at about 10 months and breed in their first spring.

Mortality and Longevity

  • The life span of a mole ranges from four to six years.
  • Moles sometimes come to the surface at night to search for food, nesting material and new territories. Because they move slowly, they are vulnerable at that time; owls and snakes can prey upon them.
  • Moles have a strong, musky odor that most mammalian predators find unpalatable. Raccoons and coyotes do dig them out, however, and (presumably) eat them. Domestic dogs and cats also kill moles but rarely eat them, apparently because of the odor and taste.
  • Spring floods kill many moles, especially young ones.
  • Humans kill many moles.
American Black Bear - Photo by: Alan Bauer

Figure 1: Photo Credit - Jim Pruske

Notes on Shrews

Although shrews (Sorex spp.) are one of our most common mammals, inhabiting areas from sea level to high alpine meadows, they are among the least well-known. They are Maine's smallest mammals; the pigmy shrew is no bigger than the human thumb. They are mouse-like in proportion but unlike mice have long, pointed muzzles and minute eyes. Most shrews are less than half the size of adult mice. Shrews are blackish or brownish in color with a pale belly. (Fig. 1) Six species of shrew – the masked, water, smoky, long-tailed, pygmy, and northern short-tailed – are found in Maine.

Shrews prefer a moist environment because their high metabolism can cause them to become dehydrated easily. Moist environments also have a diverse and abundant food supply.

Owls and snakes prey upon shrews. Domestic cats, opossums, foxes, coyotes and similar-sized mammalian predators kill but do not eat shrews, presumably because shrews produce a musky odor from their anal glands when frightened or agitated.

Shrews are rarely considered pests. They occasionally enter homes but seldom cause any trouble other than startling someone within. Mouse-proofing techniques will also exclude shrews.

Shrews are Maine's smallest mammals.

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Signs of Moles

Moles are active all year round at any time of day, but are rarely seen due to their underground existence. They are best recognized by their molehills, which they push up along their tunnel systems. Landscaped areas and gardens provide moles with the perfect place to find food. The soil is kept moist through watering and heavy applications of organic materials such as mulch, compost, and manure encourage worms and soil insects.

A mole's territory is a maze-like system of connecting, intertwining underground tunnels located at various depths. (Fig. 2) It is an ideal fortress in which to survive threats, either natural or manmade — drought, freezing temperatures, predators, toxic gases, and other poisons.

Tunnels

Moles construct two kinds of tunnels – surface tunnels and deep runways. Surface tunnels are located one to four inches below the surface. These appear as three-inch wide ridges or rips in the lawn or soil, or as puffed-up areas in mulch. In lawns, surface tunnels are often held together only by the surrounding grass roots, and you may see or feel the ridges as you step on them. Surface tunnels wind around with no apparent direction or plan; they are used once or revisited several times for feeding purposes, and possibly for locating mates in the breeding season. Moles routinely scent-mark their tunnels while patrolling for insects and other invertebrates that travel or fall into their tunnel systems.

American Black Bear - Photo by: Alan Bauer

Figure 2: Drawing Credit - Jenifer Rees

Surface tunnels connect with deeper runways that are located three to 12 inches below the surface, but may be as deep as 40 inches. Deep runways are main passageways that are used daily as the mole travels to and from surface tunnels and its nest.

Moles are fast diggers and can tunnel at a rate of 15 feet per hour. In favorable areas, shallow tunnels can be built at a rate of 12 inches per minute. Digging is most pronounced when the soil is moist and easy for moles to work. In periods of dry weather or drought, moles tunnel deeper, near moist, cool areas (for example, along sewer drain fields and under sidewalks, rocky areas, and shady fence-rows) where insects and worms congregate.

Cross-section of a mole's runway system (Fig. 2). A single mole can construct 200 mounds over the course of a summer.

American Black Bear - Photo by: Alan Bauer

Figure 3: Photo Credit - Jenifer Rees

Molehills

To create tunnels, the mole muscles its way through the soil with swimming motions, pushing the soil aside with alternating left and right paw strokes and compressing it against the tunnel walls. The large, thick, clawed forepaws do the digging, while the small hind feet provide leverage against the tunnel sides. The soil excavated from the deep tunnels is pushed to the surface through vertical shafts and forms the surface mounds, or molehills.

Molehills occur in the moist, loose earth found at the edges of woods and in fields, lawns, and other grasslands where food is available. (Fig. 3) Excavated materials are piled in roughly circular mounds that are 6-24 inches in diameter and two to eight inches high. The opening to the burrow is near the center of the mound and is always left plugged, but the plug often lacks definition.

Moles pile excavated material in roughly circular mounds that are six to 24 inches in diameter and two to eight inches high.

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Preventing Conflicts

Before trying to control moles, be sure that they are truly a problem. They can be an asset, as they eat many insect pests and improve soil aeration and drainage. They may inadvertently heave small plants out of the ground as they tunnel, or damage plants when their mounds cover small seedlings. The easiest way to prevent minor plant damage is to regularly visit problem areas, taking a few moments to reposition or uncover plants as needed.

Moles and voles (large mouse-like rodents which also occupy mole tunnels) can be found in the same locations, and positive identification is needed as control methods differ.

Extermination is impractical, especially if the property provides or borders mole habitat. While you may be able to remove existing moles or drive them elsewhere, if you have suitable conditions and moles live nearby, some will eventually move back into the area. Mole problems can rarely be resolved by a quick fix, but require a continuing commitment.

To remove the signs of moles, try the following:

Molehills:

Remove them as they appear or before mowing by shoveling up the earth, scooping up the earth with your hands, or spreading it in place with a rake. Grass seed can be spread over large, bare areas. Surface ridges: Flatten these ridges with your foot.

Run depressions:

Bring in sand or screened dirt to fill the depressions and then reseed.

To render mole activity less obvious, try adopting a more naturalistic landscape style and let the lawn grow up to hide mole activity. Cut grass with a weed-whacker to the desired height as required for a semi-tidy look. You can take advantage of the mole's soil preparation by planting shrubs and other plant material directly into mole mounds. This process eventually transforms the lawn area into a wildlife-friendly landscape setting where mole activity goes unnoticed. The subterranean life your wild neighbor leads beneath your feet is there for your understanding and enjoyment if you so choose.

Many techniques are said to repel moles, but these techniques have, at best, produced limited success.

Repellents:

At this time, there are no repellents that will reliably protect lawns or other plantings from moles. Sometimes people mistakenly think they have successfully repelled a mole because they don't see new molehills for long periods following use, but the absence relates to the mole's habits, not the repellent.

Moles are relatively solitary animals except for when breeding and rearing young, and they have large, complex tunnel systems that may extend for several hundred lineal feet. Moles may work one portion of their tunnel system for a few days and then move some distance away to another portion of the system, which may be in the neighbor's yard. Hence, the application of an obnoxious substance just prior to or immediately following the mole's shift in its feeding location will be credited to the effect of the repellent. When the mole returns a week or two later, the gardener is convinced it is a new mole.

Placing ground or broken pieces of glass, used razor blades, sections of barbed wire, a poorly set trap, or thorny rose bush canes in tunnels does not work and is more hazardous to the gardeners than the moles. When moles run into an unfamiliar foreign object in their tunnels, they may simply circumvent the object by blocking off that section with soil and digging a new tunnel.

Techniques such as placing mothballs, garlic, or spearmint leaves in tunnels, or planting a perimeter of Mole Plant (Euphorbia lathyris), have produced mixed results.

Another Homemade Mole Repellent?

Commercially available castor oil-based repellents have been scientifically tested on moles in the Eastern United States with some success. The theory goes like this: The repellent coats earthworms and other prey with castor oil, rendering it distasteful. When a mole eats coated prey, the repellent causes diarrhea. Moles then leave the treated area in search of a new and better source of food.

The following home-prepared formula has been around for many years and some gardeners swear by it while others claim it does not work. Because moles move around within their territorial burrow systems, repellents are very difficult to evaluate.

Here is the formula for castor-oil repellent: Use a blender to combine one quarter cup of unrefined castor oil, which can be purchased at most pharmacies, and two tablespoons of a dishwashing liquid. Add six tablespoons water and blend again. Use the concentrated mixture with water at a rate of two tablespoons of solution per one gallon of water. Use a watering can or sprayer to liberally apply the solution to areas where moles are active. This formula will treat approximately 300 square feet.

The repellent will be most effective where it can be watered into the moist soil surrounding surface tunnels made by moles. Areas that receive extensive irrigation will quickly loose the repellent to leaching. For best results, spray the entire area needing protection, as moles will burrow under a perimeter treatment.

The repellent may need to be reapplied before moles depart. Once moles move elsewhere, the solution usually remains effective for 30 to 60 days.

Scare tactics:

Although numerous devices (including vibrating stakes, ultrasonic devices, pinwheels, etc.) are designed to frighten moles, moles do not frighten easily, probably because they are repeatedly exposed to noise and vibrations from lawnmowers and other power equipment, sprinklers, and humans.

Note: Be skeptical of commercial products and claims, and make sure the manufacturer offers a money-back warranty if the product proves ineffective.

Food reduction:

It is often suggested that eliminating grubs from an area will get rid of moles. Grubs, however, make up only a portion of the mole's diet. During dry periods, moles are known to frequent well-irrigated lawns just for moisture. Thus, moles often are present in grub-free yards. Although repeated insecticide application may kill all earthworms, grubs and other soil animals in a lawn, there will be no immediate reduction of moles and little likelihood of long-term control. In the process, these insecticides may poison the ground water, kill beneficial soil invertebrates, and damage songbirds and other desirable wildlife.

Barriers:

Constructing an underground barrier to keep moles from tunneling into an area can be labor-intensive and costly; however, this technique is recommended for exceptional situations.

Natural control:

Predators – including snakes, dogs, and coyotes – kill moles. Owls and other raptors prey on dispersing juvenile moles. Predators alone won't always keep mole populations below the desired level in gardens and landscaped areas, but when combined with other strategies (including tolerance), natural control can be a piece of the puzzle.

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Lethal Control

Because moles are territorial, removing them from an area may appear to solve the problem. However, other moles will eventually enter the area if attractive habitat is available. Long-term control is possible by reducing or eliminating the mole population by trapping, and then continuing with a maintenance-trapping program to remove invading moles as they become evident. Moles can be controlled any time, but it is best to concentrate the effort before they give birth late March through early May.

Trapping:

Although it is time consuming and often provides only temporary results, trapping is the most effective method of mole control. (See "Legal Status" for important information) An understanding of mole behavior will help improve trapping success. When a mole's sensitive snout encounters something strange in the tunnel, the mole is likely to plug off that section and dig around or under the object. For this reason, traps are generally set straddling or encircling the runway, or are suspended above it.

Several types of mole traps are available from hardware stores and farm supply stores, and work well if used according to the manufacturer's instructions. The Out O' Sight® , the Victor® harpoon-type, and the Nash® mole traps are thought to be the best, but people have success using the Cinch® and NoMol® traps as well. Before purchasing a trap, consider your ability to set it. Good hand strength is needed to set many mole traps.

Avoid newly marketed mole traps until they have been proven effective in the field, as most new traps will not measure up to the best mole traps currently marketed.

Poisoning and Stunning:

Since moles feed on insects and worms, poisoned baits have proven to be ineffective. A new gel-type bait has been registered for mole control; however, it has not been on the market long enough to determine its control value for Maine moles. If toxic mole bait is used, follow all label directions to prevent the possibility of poisoning non-target wildlife species, domestic animals, or humans.

Gas cartridges and smoke bombs are unreliable. Their effectiveness is probably compromised by the extensive nature of mole tunnel systems and because gas diffuses in soil. Moles will seal off their burrows in seconds when they detect smoke or gas. If using gas cartridges, use them only on moles that have just invaded an area, as their burrow systems will be less extensive. Apply cartridges in two or more locations of the main tunnel (not shallow feeding tunnels) of what you believe to be the burrow system of one mole. Wetting the soil surface of the garden or turf prior to the application will aid in trapping the toxic gas in the soil.

Because moles are sensitive to concussion, smacking a shovel on the ground above a mole that is in a surface tunnel will often kill it.

Flooding:

Moles can easily withstand normal garden or home landscape irrigation, but flooding can sometimes force them from their burrows where they can be quickly dispatched with a shovel. The entire tunnel system will need to be flooded quickly and completely; a hose is too slow, so use five-gallon buckets of water. Flooding has the greatest chance of succeeding if moles are invading the property for the first time. Where they are already well established, their systems are too extensive. For best results and for humane reasons, concentrate the effort in late winter and early spring, before moles give birth. Be careful when attempting to flood out a mole near a building; doing so could damage the foundation or flood the basement or crawl space.

Shooting:

Since moles spend most of their time underground, shooting is impractical unless you have the time and patience to wait for one to be active at or near the surface. For safety considerations, shooting is generally limited to rural situations and is considered too hazardous in more populated areas.

Follow-up:

Once moles have been controlled, monitor the area on a regular basis for signs of their return. If resident moles are trapped out, nearby moles often migrate into and use established tunnels. Moles always take the path of least resistance, so taking over established mole tunnels fits that pattern. To help monitor the area, level all existing mounds so you can easily see fresh mounds.

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Public Health Concerns

Diseases or parasites associated with moles are rarely a risk to humans or domestic animals. Cats that are allowed to hunt outside may bring dead, uneaten moles inside the home. Dispose of these carcasses by placing a plastic bag over your hand, picking up the dead mole, turning the bag inside out while holding the animal, sealing the bag, and discarding it with the garbage. Using a plastic bag in this manner reduces the potential for flea, tick or disease transmission.

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Legal Status

Moles are unclassified. When moles are causing damage to crops, domestic animals, or other property, people may trap them or kill them on their own land.

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Additional Information

Books

New England Wildlife, Habitat, Natural History, and Distribution
Written by: Richard DeGraff, and Mariko Yamasaki
University Press of New England, 2001.
(Available from: www.upne.com)

Royal British Columbia Museum Handbook: Opossums, Shrews, and Moles of British Columbia
Written by: David W. Nagorsen
Vancouver, BC: University of British Columbia Press, 1996.

Prevention and Control of Wildlife Damage
Written by: Scott E. Hygnstrom, et al.
University of Nebraska-Lincoln, Institute of Agriculture and Natural Resources, 1994.
(Available from: University of Nebraska Cooperative Extension, 202 Natural Resources Hall, Lincoln, NE 68583-0819; phone: 402-472-2188; also see Internet Sites below.)

Internet Resources

Adapted from: "Living with Wildlife in the Pacific Northwest"
(see Washington Department of Fish and Wildlife)

Written by: Russell Link, Wildlife Biologist, Email Russell Link, with assistance from WDFW Biologists Rich Beausoleil and Rocky Spencer

Design and layout: Peggy Ushakoff, ITT2

Illustrations: As credited

Copyright 2004 by the Washington Department of Fish and Wildlife


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