 Moles are abundant in moist, fertile, highly organic soil throughout western Washington and Oregon. Additionally, they occur in isolated areas of central and eastern Washington and Oregon. The Pacific Northwest is the home of three species of moles. Townsend's mole (Scapanus townsendi) is the largest mole in the United States and is found generally throughout western Washington and Oregon. The Pacific mole (Scapanus orarius) is generally distributed in the coastal fog belt and in sections of southeastern Washington and northeastern Oregon. Townsend's and Pacific moles, when found in the same locality, seem to live in close association. Townsend's mole is usually the more abundant of the two. The California mole (Scapanus latimanus) occurs in south central Oregon.
Moles live most of their lives in underground runways. Their presence may be determined by the low ridges pushed up as they move just under the soil surface in search of food. These runways, in heavily infested areas, form a vast interconnecting network. Moles dig runways to search for food and to provide protection and living space for travel, resting, and nesting. Some runways are major lanes of travel used by several moles. Major runways often appear under fence lines, under roads or along sidewalks, lead to watering areas, or occur in other generally protected situations. The main runways are usually about 6 inches under ground level, but may be as shallow as 2 inches or as deep as 20 inches. Extremely shallow runways, immediately under lawn turf, for instance, are feeder offshoots from a main runway and are probably used only once. The annoying mole hills are external evidence of the moles' underground tunneling activities. Moles eject up to 2 gallons of surplus dirt from tunnel workings through a lateral chimney to the surface. Moles come to the surface occasionally, mainly at night, to search for food, water, and nesting material. Migrations may occur overland also.
Moles are active throughout the year. They do not hibernate or estivate. During extremely wet or dry periods, mole activity—by external evidence—seems to lessen. Control programs will be most successful if carried on during periods of heavy mole activity.
The principal diet of moles consists of earthworms, grubs, beetles, and insect larvae. Vegetation occasionally makes up a small portion of the diet. Moles require large quantities of food. They spend perhaps half their lives searching for something to eat. The estimated yearly intake of food for a single mole is about 40 pounds. Moles travel extensively in searching for food—up to a half a mile a day. Most of this travel, luckily, is back and forth in the burrow and not in a straight line. Extensive movement contributes to the control problem because the neighbor's moles may move right in.
Moles mate from late February to early March, producing young only once a year. The young, averaging three to the litter, are born from late March to early May. Young moles spend about one month in the nest and are nearly full grown when they leave. They may sometimes be distinguished from adults by a shorter snout, slightly smaller size, and pearly gray fur. Nests are constructed underground in a fortresslike arrangement in fence lines and well-drained, slightly raised sections of fields. Large molehills (30 to 40 inches in diameter) or areas of intensive mound-building activity are probably nesting sites. Nest cavities average 9 inches in diameter and about 6 inches in height. Normally, three or four runways lead into the nest. Moles build nests of grasses or moss with a dry, inner pocket surrounded by wet, coarser grasses. Nests normally occur 5 to 18 inches under ground level.
Do not confuse moles with pocket gophers. Gophers differ from moles in their habits. It is important to distinguish between them because each requires special control techniques. Pocket gophers are root eaters. Gophers build mounds like mine dumps, by pushing loose dirt out away from the exit at one side. Molehills are built like a volcano, by upthrust of earth plugs through the center that roll down the sides.
The mole is here to stay. Extermination is impractical. The very nature of its food habits makes it hard to poison, even if poisoning methods around gardens, lawns, and home premises were really desirable. Fumigants include gas cartridges, tablets, and pellets. Fumigation with lethal gases is sometimes successful against the mole in moist, compact, clay soils. More often it is a waste of time trying to fill the porous soil of the intricate and connecting runway systems with the deadly fumes. The use of deterrents, obnoxious substances placed in the mole runs, has the local and temporary advantage of driving the animal elsewhere to find new hunting grounds. This may indeed serve the purposes of the keeper of the home premises or of the kitchen gardener. Use lye, creosote, tar, carbide, or sink flush, preferably in the deeper runways where the moles enter the premises from wastelands or borders, not where the substances will injure plants or contaminate the soil for long. Other control methods that may have individual application include digging out mole nests and shooting or stunning individuals that are working. Moles are sensitive to concussion. Smacking a shovel on the ground near a working mole often will stun or kill it. Unless most of a population of moles is taken, no residual control is effective. Some farmers have trapped 100 or more moles annually, only to be faced with the same amount of infestation the following season.
Successful mole trapping depends on learning and practicing a few fundamental techniques. Traps must be set to form an integral part of the main runway system.
Traps set in or on lateral surface feeding runways are seldom effective.
Set them at least 1 foot away from molehills to assure trapping main runways.
Probe to locate the runway and probe again to determine the direction of
the runway. 
If you are using a scissors-jaw trap, build a firm plug of dirt for the trigger pan to rest on. Insert the trap into the hole. Make sure the trigger set wire (wire that binds trap bows) can function. Press the trigger pan firmly on the dirt plug with the trap jaws straddling the runway. Remove the trap safety catch. Sift loose dirt onto the set to exclude light. It is advisable to reset traps daily during wet weather. The proper way to set a scissors-jaw mole trap is shown below. Note the
plug of soil under the trigger and the points of the gap slightly embedded
in the bottom of the runway. Sift fine soil around the jaws to exclude light
and mark its location. 
Trapping the smaller Pacific mole sometimes requires a modified technique. The scissors-jaw trap may be used on the small Pacific mole by constructing a wider bridge under the trigger or inserting a small piece of shingle under the trigger. Either adaptation effectively gives the trigger a broader working surface. The diamond-loop trap appears to be an excellent tool for capturing the Pacific mole. This trap is set in the runway with the diamond opening centered on the tunnel. Loose dirt is sifted onto the set.
Several poison bait formulations containing low concentrations of zinc phosphide and strychnine are currently available. To use, probe for the main runways, as in setting traps. Enlarge the hole by rotating the probe in the soil until a bait can be conveniently deposited. Gently cover the probe hole opening with either leaves, grass, rocks, or clods. Do not stomp the hole closed. Loose soil will be dislodged to cover the bait in the tunnel. Several applications throughout the year may be needed to obtain significant results. Results are not consistent.
If moles are deprived of their food supply, they will be forced to seek another area. Several insecticides are capable of reducing the population of earthworms and soil insects to a point where the soil no longer provides sufficient food to fulfill the mole's daily requirements. The effect on the moles cannot be expected for several weeks following treatment. This method of control is most suitable for turf areas and often will serve a twofold purpose. It can rid the lawn of harmful insects or larvae that may destroy the grass, or control nuisance insects found in lawns. Indirect mole control, through the reduction of food supply, is a comparatively expensive measure, but it is useful on turfs where moles are a constant threat. Sonic and vibration devices have not been proven effective.
Reviewed by Gary Witmer, Ph.D., USDA-APHIS. Prepared by Leonard R. Askham, Ph.D., former Washington State University Cooperative Extension vertebrate management specialist; and David M. Baumgartner, Ph.D., WSU Cooperative Extension forester. Use pesticides with care. Apply them only to plants, animals, or sites listed on the label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock. College of Agriculture and Home Economics Washington State University Cooperative Extension bulletins contain material written and produced for public distribution. You may reprint written material, provided you do not use it to endorse a commercial product. Please reference by title and credit Washington State University Cooperative Extension. Issued by Washington State University Cooperative Extension and the U. S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion age, disability, and sexual orientation. Evidence of noncompliance may be reported through your local Cooperative Extension office. Trade names have been used to simplify information; no endorsement is intended. Subject code 360. A. EB1028 | ||||||||||||||
