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Effective rodent control

One day, years ago, I returned home from university to the apartment I shared with three roommates, to find every chair we owned arranged across the entire floor like stepping stones. We had a mouse.

I, the farm girl, fearless of all savage beasts, was directed to “Get rid of it!” Getting rid of one small mouse concerned me far less than the big problems that came with it: what damage has it done, how much mess has it made, how many friends did it bring to the party and where did it get in? If I ever wanted to sit down again, I needed to solve the problem.

Controlling mice

One little mouse is a nuisance, however, each year farmers across the prairies must be on the lookout for signs of these small rodent pests. Mouse species, such as the white-footed mouse, the deer mouse, and the western harvest mouse are native to the Western Plains, and can survive in the wild. However, a nice cozy barn, haystack or farm shop makes an attractive place to spend the winter.

1. Don’t let them in

Keeping mice out of all farm buildings is always in your best interest, as mice can carry several diseases, including the potentially fatal Hantavirus.

Mice can gain access to buildings through very small openings. A mouse only needs 0.6 cm (a quarter of an inch) of space to fit through. This is about the same width as a No. 2 pencil. If it can fit its head through a hole, the rest of its body will fit also. Check foundations, door and window frames and conduit openings for cracks, and seal any openings with steel wool or a patching compound to keep mice out. Keep in mind, mice can jump up to 45 cm (18 in.), walk across wires, and climb vertical surfaces.

2. Reduce habitat

Mice prefer cover to wide-open spaces. Reducing the outside habitat around buildings may help keep mice out. Trim grass, trees and shrubs, and remove any debris piles that may give mice a place to hide. Stack all wood piles 30.5 m (100 feet) away from buildings, and when possible, raise them off the ground. Similarly, ensure that all compost, or food scraps are kept away from buildings or secured in bins. All potential food sources — like spilled grain, livestock feed, or even the pet’s food — should be cleaned up, and kept away from mice.

3. Use poison

To keep mice in check, poison may be needed. Always take care when using poison. It can be a danger to children and pets when not used properly. Fumigation, glue boards, electrocution, and basic mouse traps can also be used to control mice.

Controlling rats

As damaging and annoying as a mouse problem can be, it pales in comparison to the destruction created by the mouse’s big cousin, the rat.

“Rats are the Olympians of the rodent world,” says Rick Wanner, pest control officer for the Rural Municipality of Weyburn, Sask. “They can survive on anything.” The rat is recognized as the most destructive vertebrate in the world.

The most common rat found on the prairies is the Norway rat. It is also known as the brown, common, or sewer rat. It is not native to Canada, but entered the country in the 1700s as an unwanted stowaway. As settlers moved west, so did the rat.

The destruction caused by rats can be divided into three categories: contaminated foodstuffs, physical damage to structure, and disease transmission.

A rat eats about 10 per cent of its weight each day, or 20 to 40 kg per year, and contaminates five to 10 times more food than it eats with it’s urine and feces. Rats consume or contaminate approximately one-fifth of the world’s field crops each year, including about four per cent of all stored grains. A single rat can eat, or spoil, about $25 worth of grain each year.

Physical damage to structures caused by rats can be extensive. Rats have four incisor teeth that grow 15 cm (5 inches) each year. They must gnaw daily to keep these teeth short enough to eat. In their quest to build food access routes, nesting sites, and escape routes, rats gnaw through almost anything in their way, such as walls of various materials, pipes, hoses, and conduits of all types. Rats can do particular damage to insulation and ceilings, allowing cold air and humidity into buildings. Rats tunnelling under foundations and walls undermines structures, and allows cold air to flow through the tunnels, which may lead to heaving. Damage to electrical wiring caused by rats chewing is not only aggravating and expensive, but increases the chance of an electrical fire.

Because rats live in close proximity to humans, disease is a serious issue. Disease is spread directly from a rat bite, or rat-contaminated food, or indirectly via rat fleas acquired by pets, which come into contact with rats.

1. Be vigilant

Nobody wants a rat problem. Whether you are the proprietor of a small acreage, grain farm, or livestock operation, it is in your best interest to avoid the problem. “Vigilance,” says Pest Control Officer Wanner. “Knowing what to look for is where rat control begins. It’s the old walk around the vehicle theory. Do periodic inspections of stacks, and buildings, especially in the fall.”

When inspecting a building, check the siding for holes, or places under the siding where rats could gain access to the walls. Doors and windows should fit tight, and doors should have metal kick plates to prevent gnawing. Drains and conduits should use screens 12 mm (1/2 in.) or smaller. Areas where utilities enter buildings should be tightly sealed. Seal sandwich panels to protect insulation. Protect perimeter insulation by extending rat proof material 95 cm (3 ft.) below ground surface. Also check the foundation for, cracks or openings, and repair when necessary.

2. Reduce shelter and food

Harbourage is the next step in preventative rat control. Rats cannot survive or reproduce without shelter and food. Spilled grain, or access to grain, is the number one food source of rats. “Clean up spilled or rotten grain in bin areas, and when using grain bags, clean up the site, and dispose of the grain bags,” says Wanner.

Don’t dispose of those grain bags in the farm junk pile, as they will still be attractive to rats. In fact, it is a good idea to clean up the junk pile, which may become an attractive place for rats to live. Rats, like mice, do not like open spaces. Trim grass and trees, and stack lumber piles away from buildings, and off the ground. Wanner cautions that bale stacks, in particular, should be located away from buildings, and checked regularly. “Old bale stacks are like A&Ws for rats — especially straw stacks, because there is always something to eat in them.”

3. Bait stations

Along with vigilance, and removal of harbourage, Wanner recommends the use of a preventative bait station. Various types of homemade bait stations can be constructed and strategically placed, or commercial bait stations can be purchased.

Warfarin, an anticoagulant, is the poison most often used. When using a bait station, care must be taken to avoid the accidental poisoning of pets, other non-target animals, and children. Other forms of rat control may include a basic snap trap, glue boards, fumigation and electrocution.

“Use your pest control officer,” says Wanner, “because we are trained for signs of rat activity, and proper placement of bait stations.” And, furthermore, “Don’t lie to your pest control officer — cats don’t cut it!”

Seek help

If you think you have a rodent problem and you live in rural Saskatchewan, call your local Rural Municipal Office to get in contact with the R.M.’s Pest Control Officer. If you live in Manitoba, contact Manitoba Conservation 204-944-4888. In Alberta, contact your County Office and an agricultural field man will help you deal with the problem.

As for the mouse in my apartment, a well placed snap trap proved to be its demise. Apparently it had a weakness for peanut butter. The damages were limited to a few items in the pantry, and if it brought friends, they were all very sensible, and exited where they came in — where ever that was. I never did find out. I did, however, get to sit on my chairs again. †

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