GROW SMART, GROW SAFE

   Animal pests >> Moles and voles  

Moles, voles, rats, mice, deer and birds are not always the best garden guests. While they can help your garden in different ways, you may need to respond to them as pests from time to time.  There are many ways to keep unwanted animals out of your yard and prevent them from causing damage. Fences, traps, screens, baits and chemical repellents are some examples.

You can prevent animal pest problems without toxic chemicals using the research-based strategies described here. You can also find least-toxic pesticides and learn about the hazards of particular products using the Grow Smart, Grow Safe search tool.

Moles

Moles eat insects, and their digging can help the soil. These burrowing animals – especially active in warm weather and after a rain – leave ridges and mounds in lawns. They rarely eat flower bulbs or roots, but plants may be physically disturbed while they are tunneling for insects. Moles are tough to manage, so you may need to use several different methods.

Prevent problems before they appear

You can’t prevent moles in your lawn. Consider shrinking the lawn if they cause damage year after year.

• Replacing part of your lawn with garden beds attracts birds and butterflies and reduces visible mole damage.
• Use hardware cloth baskets set into the ground to surround and protect a young plant’s roots.
• Established trees and shrubs are usually safe from physical disruption.

Manage problems wisely

Identify the pest. Because moles are rarely seen, base your identification on the signs they leave behind. Moles excavate two types of tunnels: shallow feeding tunnels and deeper network tunnels between these feeding tunnels. It’s the volcano-like mounds from these deeper tunnels that identify the mole’s work. Pay attention to where the mounds pop up; you're likely to see the moles moving to your neighbors' yards after a few weeks.

Rake down the mole hills. The mounds are prime top-dressing delivered right to your site – free of charge!

Traps are the most effective mole control. It’s tough to trap a mole correctly, and traps can be dangerous, so get and follow detailed instructions. Mole trapping is allowed in Oregon and in Washington with restrictions. For information, visit http://wdfw.wa.gov/wlm/living/moles.htm.

Castor-oil and noisemakers have mixed results. Castor-oil repellents may help in the short term. Devices that make noise or vibrations may not be effective all the time. Flooding and fumigating rarely work either since nearby moles will move into the vacated tunnel.

Don’t use a pesticide that kills grubs or earthworms. The moles and their damage won’t all disappear, and in the process you will kill earthworms that help your soil.

Voles

Voles are scavengers and primarily vegetarian. They eat grasses, bulbs, seeds, flowers, leaves, roots of shrubs and small trees, bark, tubers and sometimes insects. Like moles, they live in underground burrows, and their tunnels are usually just beneath the surface, under grass or ground covers. They often use mole tunnels. Much of the damage we blame on moles may be the voles’ work.

Prevent problems before they appear

Identify the pest. Voles are brown, about 6 inches long and have a long rat-like tail. They live in burrows and leave tunnel openings on lawns, in the open garden, on fields and around emerging plants.

Remove shelter. Voles like places to hide from predators.

• If you reduce their shelter, you can reduce their numbers.
• Remove weeds and dense vegetation.
• Mow or till grassy areas and fields near your garden.

Fence them out. Protect young trees and ornamentals by placing a cylinder made from hardware cloth, sheet metal or heavy plastic around the trunk. Surround small plants with cylinders made by cutting the tops and bottoms from plastic soda bottles, tin cans or milk cartons.

Manage problems wisely

Repellents can help. Chemical and natural repellents may initially seem effective against voles, but they need to be reapplied frequently and voles become accustomed to the smell. Success is measured by the reduction – not total elimination – of damage.

Be careful with traps or baits. Ordinary mouse traps may be effective if voles are in a small area or if their numbers are small. Poison baits are potentially hazardous to other wildlife, children and pets.