Gopher & Mole Problems

Gophers and moles are burrowing animals and both are considered garden pests. Gophers are vegetarian, eating 60 percent of their body weight each day in roots, bulbs, seeds and tree bark. Moles eat insects, larvae, earthworms and only a little vegetation. The greater harm to home gardens is done by gophers.

Geography

Gophers, also commonly called pocket gophers, are found throughout North America and into Central America. Moles can be found in most parts of North America, Asia, and Europe. None are found in Ireland.

Season and Time

Gophers usually mate and raise their broods in spring and summer. Some species breed several times in a year. They have litters of two to five or more young. Gophers do not hibernate. They can be active all year and around the clock. Moles breed from late winter through spring and have one litter each year of two to five.

Identification

It is easier and more useful to identify these garden pests by the evidence they leave behind than it is to find the elusive animal. Holes excavated by moles are less extensive than those of gophers. The mound of excavated soil at the tunnel entrance can help you identify the animal. The gopher burrow entrance is angled and can be crescent shaped, with soil pushed to one side. The mole mound is often mounded all the way around the entrance, resembling a volcano.

Types of Damage

Gophers are ravenously hungry eaters of garden plants. Vegetable gardens, ornamental shrubs, trailing vines and trees fall victim to gophers. They gnaw plastic irrigation systems and sprinklers. They dig tunnels that can redirect irrigation water away from plants where it can erode soil. Their mounds can pockmark lawns and make mowing a nightmare.

Moles mostly stay in their underground burrows, preferring moist, sandy loam garden soils to heavy, dry clay soils. Like gophers, they build complex passageways underground and they leave mounds above ground. They damage plants when they expose roots to air.

Eradication Methods

Traps are available at garden supply and home improvement stores. Trapping is difficult because burrowing animals seldom venture more than a few feet from their tunnels and their tunnel systems are deep and complex.

Garden pests may tempt gardeners to use harsh measures. Grain bait treated with strychnine is commonly used for gopher control. The bait is lethal in a single dose if the gopher eats it. These baits create problems in the food chain when predators eat a poisoned gopher or birds or other small animals eat the bait meant for the gopher.

You can use anticoagulant baits also. The advantage of these is that they are less toxic. The disadvantage is that the gopher may need to ingest several doses, about 10 times the amount of the strychnine baits.

Gophers are smart and protective of their tunnels. If you try to use smoke or gas cartridges, they will respond by sealing off their tunnels. Commercial pest control companies usually have access to aluminum phosphide and appropriate applicators for fumigation.

Natural Controls

One imperfect method for keeping gophers out of garden beds is to lay mesh poultry wire before building up soil in the bed. Lay the mesh at least two feet under plantings and extend the wire at least one foot above the ground. Gophers cannot burrow through the wire. The wire can, however, restrict and even damage root growth, especially of trees and taller plants. Gophers may be undeterred anyway, waiting for roots to grow downward and then pulling the roots to nibble them.

You might think that gopher populations will naturally level off in time. The answer is yes, they probably will, but the leveling off will not happen before your home garden is damaged. Snakes and owls, dogs, cats and coyotes eat pocket gophers if they can reach them. Gophers are adept at making an earthen plug and pushing it into place to keep snakes out of their tunnels.

You can create a rock or other no-grow buffer zone around gardens and lawns to make getting to the lawn more difficult. This is a simple mechanical way to discourage gophers by putting their prospective food sources slightly out of reach.

You can also put a hose down the main tunnel and attempt to force the gopher so you can destroy the creature with a shovel or hoe as he tries to escape.

Misconceptions

Here are some methods that have been tried unsuccessfully to eradicate gophers and moles:
Repellents including gopher purge, castor bean and garlic
Vibrating stakes
Ultrasonic devices
Pinwheels
Chewing gum or laxatives dropped into burrows

References

• University of Wisconsin: Pests: The Vermin Report: Gophers
• University of California: Pocket Gopher Management Guidelines
• University of Missouri: Controlling Nuisance Moles