Moles – n – Voles – n – Gophers… Oh My!!
Another non-disease related article this week, but we are still covering pests – this time of the animal variety. As we may have seen our last snowfall of the 2011 winter on Monday (the Farmers Almanac doesn’t think so), more and more homeowners and turf managers are noticing the damaging effects of burrowing mammals. At the fault of perhaps the best movie of all time, many may blame gophers for this damage. The glorified gopher is not the biggest villain of landscapes in Missouri, however, as moles and voles are by far more widespread and destructive.
The most common mammal disruptor of turfgrass areas in Missouri is the eastern mole (Scalopus aquaticus). Moles are related to shrews, and are not rodents. Moles are insectivores feeding sparingly on white grubs and other insects, but their preferred food source is earthworms. Although we commonly think of snakes and spiders as being venomous, moles reputedly have a toxin in their saliva that induces paralysis in earthworms. These earthworms are then stored in a “larder”, or underground pantry, for future consumption.
Mole damage can be distinguished in two ways. Moles are usually more damaging because their tunnels are nearer the soil surface (2-3 inches deep), whereas gophers dig deeper tunnels (5-8 inches deep). Molehills normally make mounds that look more like mountains, with the plug or exit area directly in the middle of the mound resulting in a peak. Gopher mounds will have plugs to the side of the mound, resulting in a kidney-shape (see figure above).
Voles, also called meadow or field mice, can cause damage to turfgrass areas by building extensive surface runway systems under snow cover, as opposed to tunneling deep into the soil (see figure above). To tell the difference between moles and voles, think of moles as tunnel rats (although they aren’t really rodents!) and voles as trench builders. As the name suggests, the most common vole in Missouri is the prairie vole (Microtus ochrogaster), although 23 different species of voles reside in the United States. As you may suspect by they’re alternative mouse name, voles like gophers are true rodents. They live in colonies and can be voracious herbivores, eating turfgrass sod during spring and fall. They also can be a considerable problem in alfalfa fields, eating corn and soybean seedlings in no-till cropping systems, and girdling and killing ornamental and orchard plantings (remember they have to gnaw to keep those incisors down!).
Although it gets top-billing in the media, the gopher is usually not the biggest offender in damaging turfgrass areas in Missouri. The pocket plains gopher (Geomys bursarius) is the most prevalent species in the Midwest. Gophers are classified as rodents, which means they have two large incisors in the upper and lower jaws, which must be kept short by gnawing (see photo above). As with most rodents, gophers feed on plants, including a variety of grasses and legumes, and are reportedly very fond of alfalfa.
In many cases, moles and voles are minor nuisances and thought should be given whether control practices are necessary. If control is warranted, identification is important since control practices can vary somewhat for each one of these burrowing mammals. Control practices fall under a few main categories; some of which are summarized below.
TrappingTrapping is one of the most effective and highly recommended means for removing small infestations or removing animals from smaller areas. Since the lifestyles of the three animals are different, the trapping style also varies. Effective mole trapping relies on finding active tunnels. Do this by poking holes throughout the tunnel network, waiting a few hours, and placing traps where the moles have patched the holes. Gopher trapping relies on finding the main tunnel, which is normally 12-18 inches away from the plug (see Gopher figure B above). Gopher traps are then placed inside the tunnel.
Some repellents are on the market to keep moles in your neighbor’s yard. Most of these repellents are based on castor bean oil, and require repeated applications. Most have been tested as effective against the eastern mole, our predominant species.
Several mole baits are on the market that are flavored like earthworms, and require ingestion of a toxin. Some resemble earthworms, while others are granulars. All of them are to be applied into active tunnels. Some of these baits include MOTOMCO Mole Killer (worm-shaped), Talparid (worm-shaped), and Mole Patrol bait (granular). Baits containing zinc phosphide have been used for effective control of moles and voles, but have limited effectiveness gophers. Gophers are most effectively controlled with baits containing strychnine alkaloid.
A word of warning with all of these baits is to treat them just like common rat poison. Keep children and pets away from treated areas and follow label directions carefully.Fumigants
Most are restricted use fungicides and not suggested. For gopher control, however, (which is rarely needed in MO), an article suggests the use of carbon monoxide by hooking a hose up to your automobile’s exhaust, sticking the hose in the gopher plug, and running the vehicle for 3 minutes. Ninety percent effectiveness is claimed. If only Carl Spackler knew…
The following are a few useful links for more information on identifying and controlling burrowing animal problems.
http://www.guildofbritishmolecatchers.co.uk/ - Become a member of The Guild of British Molecatchers!!
Save the Date:; July 26, 2011
Make plans to join us at the University Missouri Turf & Ornamental Research Farm on July 26th for our annual field day! We will be presenting the latest research on cultivar evaluations, pest controls, and management considerations for turf, trees, and woody ornamentals. It’s a fine day and a fine way to interact with colleagues and your local Mizzou research team.
Extension Turfgrass Pathologist
University of Missouri
Extension Turfgrass Specialist
University of Missouri