Pest Patrol

Pests of all shapes and sizes can wreak havoc at a barn. Here's a look at keeping unwanted critters at bay.

The most destructive pests in barns, sheds and stable areas are rodents. Rats, mice, field mice and voles eat grain, munch on straw and hay bales (and contaminate the area with urine and droppings). They chew holes in feed sacks, saddle blankets, tack, and exposed wiring. They shred any handy material to make nests. In short, they gotta go.


Besides being destructive, rodents may bring disease into your barn. Human illnesses associated with rodents include bubonic plague (spread to humans via fleas from infected rats), typhus, salmonellosis, trichinosis, listeriosis, and Hantavirus (see sidebar). Certain species of mice can spread Lyme disease, since they are host to deer ticks that carry these bacteria.

Rodent droppings and urine can also spread several equine diseases. Rodent urine is the primary source of the bacteria that causes leptospirosis in humans and horses. Leptospirosis can lead to abortion in pregnant mares or damage to the eyes that results in moonblindness (periodic opthalmia). Therefore, grain or hay that has any evidence of rodent activity and contamination should be disposed of.

Salmonella may be passed to horses from rodents via contaminated feed. Affected horses may become ill and develop severe diarrhea. Rodents also present a hazard if a dead one ends up in the feed and its decomposing body releases toxins created by Clostridium botulinum, the pathogen that causes botulism.


It is no small challenge to evict or keep out rodents, and it usually takes a combination of tactics. Diligent cleanliness is the first line of defense, reducing the amount of food and nesting material available to these freeloaders. Keep your grain, feed mixes and supplements (and any garbage) in rodent-proof containers with tight-fitting lids.

Next, mouseproof your tack room, if possible. Mice can wiggle through an amazingly small space; if they can stick their head through, they can get their body through. Check all walls, flooring and ceilings to make sure there are no places where rodents might come through—especially in corners, and around water pipes or vents. There’s often some extra space where pipes come through a wall, and these holes can be a rodent freeway.

Any cracks wider than 1/2 inch should be sealed. Caulking material will work for small cracks, but mice will chew through it in a large crack. Coarse steel wool works well for plugging small holes in floors, walls or corners, since mice won’t chew through it and it can be easily poked into odd-shaped holes or crevices. It generally makes an effective block that stays in place for years. Block larger holes with lightweight sheet metal or fine mesh wire screen, nailed into place. If there’s space under the door, add a threshold that meets the door more closely.

Store all tack and horse blankets up off the floor. A heap of material or leather items makes a wonderful hiding place. Rodents also like to chew on leather (and wool linings!) and can ruin your best tack. If it’s not possible to eliminate all rodents, tack can be stored in a cedar chest (which not only keeps out mice but the smell deters moths and insects). Mothballs will also repel rodents and can be hung in plastic bags next to your hanging tack.Inside the barn, get rid of anything that might provide refuge for rodents, such as old boxes or newspapers. Don’t store hay or straw or other materials in the barn if you have any other option (for fire safety as well as rodent control), since piles of stuff make a safe hiding/nesting place for rodents. Haul spilled grain, used bedding or any other debris well away from the building so it won’t be nearby to attract rodents. Eliminate any water leaks from pipes or hydrants since moisture or puddles make handy drinking areas.

Outside the barn, clear away all lumber, debris, weeds or tall grass around buildings to eliminate places where rodents can hide. Open spaces next to barns or sheds tend to be a deterrent for rodents, since they prefer the cover of protective vegetation to stay safe from predators. Don’t stack hay or straw next to the barn, either; make sure it’s not just a hop and a skip from the hay pile to the barn door.


If you have a large population of rodents you may have to resort to traps and/or poison to get rid of them. Another alternative is a rodent repellent such as an electronic device that emits a high frequency sound that neither you nor the horses can hear, but is disagreeable to rodents.

Traps or poison should be placed on or near the rodents’ regular runways or entry holes. Mice are fairly easy to trap or poison because they are less suspicious than rats and more readily attracted to traps or bait stations. It may take more strategy and persistence to catch rats. Usually the best tactic is to use several traps and place them wherever there is evidence of rodent activity (droppings, signs of gnawing).

Should you use traps or poison? That depends on your situation. Traps are safer than using poison if you have pets or small children in the barn, but have the disadvantage of being labor intensive. You need to check them daily and reset them or rebait them, removing any dead rodents. Poison has the advantage of being less time consuming—put it in strategic areas and replenish it now and then.

Inexpensive snap traps (rat or mouse size) can be effective in areas of rodent travel. Position each trap so a rodent must travel directly over the trigger. A trap along a wall should extend out from the wall at a right angle, with the trigger end touching the wall. The rodent uses whiskers as feelers to follow the wall and is likely to feel his way around trap placed parallel to the wall, rather than walk over it.

Snap traps are still one of the most effective ways to catch mice, but must be hair-triggered or mice will eat bait off without springing it. Some mice are adept at carefully taking the bait, but if you have several good traps in the same area, you’ll catch them sooner or later. A mouse taking bait from a snap trap and not getting caught may become more bold and less cautious when he tries the second one. If mice continue to steal the bait, one solution is to tie bait to the trigger with thread. Then mice can’t get the bait without pulling on the thread, which creates enough movement to set off the trap.

If using brand-new traps, put bait on them a few times without setting them, so the mice (or rats) become accustomed to dining there. After they’ve taken the bait a few times, go ahead and set the traps. Reusing old traps is generally more successful than using brand new ones; the rodent smell on a trap makes the animals feel more comfortable about it (and less suspicious), and encourages them to try the bait.

Nearly any type of food can be used as bait; mice will try peanut butter, bread (especially with butter on it), bacon, dried fruit, nuts, cheese, etc. Keep the bait fresh, because it’s more attractive; if bait has been on a trap too long and is stale/dry or no longer has an enticing odor, rodents may ignore it.

If a rat is too suspicious to try regular bait, use a muskrat trap covered with a handkerchief or small piece of sheet. Rats are curious and will usually check it out, and get caught. Anchor the trap securely so the rat can’t run off with it if it merely catches him by a leg. Use wire to secure regular snap traps to overhead rafters, beams or pipes if you are trying to catch pack rats or roof rats.

Glue board traps (such as the J. T. Eaton Stick-Em boards) are another option. Glue boards catch a mouse or rat when they step onto the sticky surface. The traps are pre-baited and non-poisonous. They should be placed lengthwise along a wall or baseboard where mice habitually travel. If a rodent steps on one of these, whatever part of his anatomy touches the trap is stuck, and he’s soon completely mired. The glue board should be discarded along with the caught mouse. If you accidentally get your fingers stuck to the adhesive, you can clean them up with baby oil or cooking oil.

When using any kind of trap, it helps to use them in pairs. If a rodent jumps over the first one, he may land on the second one.

Other types of traps that can be used include flip boxes, which toss mice into an escape-proof container when they pass over a triggering mechanism or enter a hole in the side of the box. These traps often work if placed next to mouse holes or along their regular runways.

Poisons are a second means of eliminating pests. Poisons for rodents usually contain anticoagulants that cause fatal hemorrhage, but may require several doses (repeated feedings) to kill them. Grain-based baits in meal or pellet form can be scattered along runways or other areas of rodent activity. Bait bars or rodent blocks can also be nailed to vertical surfaces along rafters or other off-the-ground rodent runs.

If you opt to poison your pests, bait bars area a good choice, since rodents like to gnaw the bars. Some, like the J.T. Eaton bait block, are flavored with molasses and peanut butter. For rats, the product instructions are to put out 2 to 8 blocks per placement, keeping up a continuous supply of fresh blocks for at least 10 days. For mice, the blocks should be broken up (while wearing waterproof gloves) into 3 pieces. Scatter these in areas of high mouse activity, with fresh bait provided continually for at least 15 days.

Some rodent poisons are available in water-soluble concentrates to produce a liquid bait. These are attractive to rodents in an area where there’s plenty of food available but no water source (such as a tack room or feed room). There are also tracking powders that can be applied in a thin layer (using a squeeze bulb) along a rodent runway or in a bait box. The powder sticks to fur or feet of rodents as they travel over it; they eat the poison when they groom themselves, or carry it with them back to their nests where it may kill other rodents.

When using poison, the object is to get the animals to eat enough of it to kill them. Make sure the poison is in areas where small children or pets won’t find it. Always read labels when using rodent poisons, and follow directions. Collect and burn any dead rodents you find.

For a third option, consider a rodent repellent. This little device can be plugged into any electrical outlet. It may not evict all of the resident rodents but often deters “new boarders” that might otherwise come into the barn.

One example is the Pest-a-Cator ( that sends out sound waves in a patented electro-magnetic pulse technology. It also sends a pulsing signal throughout the wiring of the building. This tends to annoy rodents, even the ones within the walls, under the floors, or in the ceiling. For a big problem area, the device can be plugged into an unobstructed outlet in the infested area. This repelling device usually helps reduce the rodent population within two to four weeks and then deter newcomers. In the meantime, however, you may need to use traps or poison for faster reduction of the population.

Ridding your barn of rodents is not an easy task, but there are several means to accomplish it. Be persistent, diligent, and flexible. And be brave—remember who is man (or woman) and who is mouse.






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