Rooting out rodents

My first experience with voles occurred in the early 1980s when I had started a Christmas tree plantation. The trees were 3 to 5 years old and were growing nicely. Late one spring, I noticed that an occasional tree here or there would slowly turn brown and die. I found that these trees had been girdled at the ground line by some unknown varmint.

A few months later I was called to look at a damaged lawn. There were several "runs" along the surface of the ground, and several 1-inch holes were bored into the soil near the sidewalk connecting the street to the front porch.

After several phone calls to experts, and a lot of reading in technical books, I found that the culprit common to both situations was the vole, a field mouse. Although common to our area, I find that few people are aware of voles. Most people think that when I mention voles, I am really talking about moles. But I can assure you that they are two separate entities.

Voles are members of the genus Microtus. In the United States, seven different species inhabit the Great Plains states, but their ranges may or may not overlap. Usually three different species can be found in Southeast Missouri.

Voles are usually 4 to 8 inches long, including the short tail. They are similar in appearance to a house mouse. They are usually found in areas where there is a lot of dense ground cover, such as leaf debris, lawns or mulch in landscape beds.

Voles are primarily vegetarians, feeding on seeds, roots and tops of small herbaceous plants. They also feed on bark, as seen by my Christmas tree plantation story. Seldom will they feed on insects.

In summer, vole damage is often masked because of actively growing vegetation. During the winter, voles remain active, and their damage becomes obvious.

The vole's home is usually a small subsurface "chamber." Each chamber is connected by a subsurface tunnel to another chamber. The entrance to these subsurface tunnels is a hole about an inch in diameter, found in surface "runs" located in and around dense ground covers. These surface runs are usually 1 to 2 inches in width.

Each vole ranges over about a quarter-acre area. Some studies have shown populations as high as 500 voles per acre if environmental conditions are just right for the species.

When vole populations expand, landscape plantings can be severely damaged. As mentioned above, obvious damage is girdling of trees and shrubs and the unsightly existence of surface runs in heavily vegetated areas.

If you find voles in your landscape, place two or three pellets of zinc phosphide or mole and gopher bait in each hole that you find. Do this every two or three weeks until you see no more evidence of vole activity.

With a little diligence you can eliminate this pesky varmint from your landscape.

Send your gardening and landscape questions to Paul Schnare at P.O. Box 699; Cape Girardeau, Mo. 63702-0699 or by e-mail to news@semissourian.com.