Weed & Pest
Common rodent pests discussed at Fremont County Farm and Ranch DaysWritten by Natasha Wheeler
Riverton – Although they may be small, rodents can adversely affect irrigation, electrical supply, crop production and tree survivability.
“They can really start causing damage in a variety of different places,” commented University of Wyoming Pesticide Coordinator Jeff Edwards.
Voles, kangaroo rats and prairie gophers are three examples of potentially harmful rodents discussed by Edwards at Fremont County Farm and Ranch Days on Feb. 11 in Riverton.
“Voles look a lot like mice, and people confuse them, but voles are stocky and have relatively short tails compared to their body,” he noted.
Their body shape somewhat resembles a guinea pig, with small ears and a grizzled-fur appearance. They range from about 4.25 to seven inches long with relatively short tails, compared to their bodies.
“There are a bunch of different species in Wyoming, including water, pine, meadow, sagebrush and prairie voles,” he explained.
Females can produce multiple litters per year, and species populations can fluctuate wildly.
“We can go for years without having voles or seeing voles, and then all of the sudden they are there,” he added.
Insects and plants make up the majority of their diet, and voles will eat grasses, sedges, alfalfa, grains and berries.
“They have the ability to go down planted rows and harvest the seeds that we have just planted,” he commented.
Voles have also been known to eat the bark, girdling the trees that they eat.
“If we happen to have fruit trees in our yard, we might want to check the bases of those trees for gnaw marks,” explained Edwards.
Vole activity can often be identified by shallow burrows extending to a series of surface tunnels that they use to stay hidden while foraging for food. Grasses near the tunnels are usually clipped short, close to the ground.
“Considered to be secretive and seldom seen, we do end up seeing the runways as a result of their activity in and around these systems,” he said.
Voles are active both day and night, unlike nocturnal kangaroo rats.
“Kangaroo rats have small forelegs and long, powerful hind legs with a long-tufted tail,” described Edwards.
Body length varies from four to six inches, with tails ranging from six to eight inches long. They typically have wheat-colored fur on their topside and white fur on their belly.
“Also, they hop. That is why they are called kangaroo rats,” he explained.
Kangaroo rats can also take planted seeds out of farmers’ fields, and they can consume large amounts of material.
“A medium population density can consume 1,300 pounds of plant material per section, as well as store 2.9 tons per section per year in burrows,” added Edwards.
That could be enough to replace six cow/calf pairs on a section.
“They are considered hoarders, and in their intricate tunneling systems, they have pockets where they bring seed back and store it for wintertime,” he stated.
Pocket gophers are also hoarders. While they are out collecting food, they pack their cheeks with extra supplies to store for later.
“The most characteristic feature of pocket gophers is their large external cheek pouches, which are actually outside of their mouths. The pockets are fur-lined, and the gophers can turn them inside-out to empty them,” explained Edwards.
Generally six to eight inches long, they have relatively short tails in relation to their body size and large front claws used for digging.
“Moles and gophers can be confused because they are quite similar in appearance. Moles have highly reduced eyes and pointier noses,” he commented.
Pocket gophers primarily eat roots, but they also occasionally eat worms or insects.
“They really like alfalfa and the roots of small immature trees,” he said.
Along with new plantings of trees, electrical wires and irrigation lines can also be susceptible to gopher damage.
“They are very territorial. If we happen to come across one of their tunnels with an electrical line or something that we are putting in, they see that as a threat, and they will start gnawing through it,” he commented.
A minimum of two-inch PVC schedule 40 pipe is recommended to protect underground lines in pocket gopher territory, as they can chew up to 2.9 inches in diameter.
“We can trap gophers,” stated Edwards.
He warned that trapping is more effective when producers understand how rodent tunneling systems work.
“If we come across a gopher tunnel, there are two directions we can go with a trap. We generally need two traps with some sort of solid spike to hold that in place,” he explained.
Baiting and bait traps can be effective for pocket gophers, kangaroo rats or voles, as long as they are used correctly. There are a variety of snap-traps for prairie gophers, rat-sized snap-traps can be used for kangaroo rats, but they are not effective for controlling voles.
“Baiting is the most common way to take care of voles,” he stated.
Kangaroo rats can often be controlled with flooding, but Edwards noted, “Although entertaining, shooting is not effective.”
For any control method, users should understand their environment and the species they are working with.
“Be sure to read and follow the labels,” Edwards said.