Voles dig tunnels in the same way that gophers and ground squirrels do. However, they create multiple holes on the surface, and they do not seal the holes at the surface. Therefore, the use of carbon monoxide is more challenging because the gas can escape the tunnel system while it is being injected, unlike in a sealed gopher tunnel.
At Idaho Gopher Control we seek to overcome this challenge by sealing or plugging the open vole burrows.
However, because voles tend to live in grassy areas, there are frequently holes that go undetected. In an attempt to locate all vole holes, we will trim the grassy areas around vole activity in an attempt uncover hidden holes.
To control voles we first inject carbon monoxide and attempt to plug all the holes in a burrow system for the most effective kill. We have dug up vole burrows after treating them with carbon monoxide and located dead voles, proving that this method works. Also, the vole burrow systems are much smaller in length and volume than gopher burrows. While treating vole burrows with carbon monoxide voles frequently come to the surface and die from carbon monoxide poisoning, demonstrating the effectiveness of this method.
Because there can be multiple breeding pairs of voles in one burrow system, and because we have seen voles re-populate covered burrow systems that have already been treated we attempt to fill the tunnel systems after treating them with carbon monoxide. A biodegradable material that expands when exposed to water is inserted into the tunnel system and washed to the bottom with water. In approximately 10-15 minutes the material, which is also used as an instant potting mix, comes to the surface of the tunnels and hardens, closing off the tunnels.
Because this product is biodegradable and is also used as a potting mix it is safe for the lawn, shrubs and trees. It will still allow drainage of irrigation water and the ability for roots to grow through it.
The closing of the tunnels with this product allow us to prevent re-infestation in treated tunnels and detect any new activity easily for quick follow up treatment. Over a period of time voles can be brought under complete control with this method and the integrity of the soil can be preserved as voles tend to cause large and small sinkholes as they continue to burrow and dig in one area if left untreated.