Getting Rid Of Mice
This advice refers to the common House Mouse (Mus domesticus), which is prevalent throughout the world. Many other species of mouse exist, however, the vast majority of them are not associated with man and are not considered as pests.
A quick note on why you should be getting rid of mice, just in case you are an animal lover and are quite happy to see the little chaps running about. Mice can carry a wide range of pathogens (harmful microorganisms) and can contaminate your crockery, cutlery, kitchen worktops and stored food. Mice dribble urine continuously, leaving deposits on any surface they travel over (if you want proof, their urine will glow when lit by a blue UV light source). Mouse droppings will also be deposited willy-nilly, wherever the mice are active.
Did You Know?
A mouse typically deposits 50-75 mouse droppings each day!
As with all rodents, their front “bugged” teeth continue to grow throughout their lifespan, so they have to gnaw on things to stop their teeth growing too long. This gnawing can cause noticeable damage to your home. Mice love to gnaw wiring, thus presenting a considerable fire hazard. I have seen several pictures of charred mouse bodies in electrical sockets that have been recovered from burned-out buildings.
Stem the Flow
There are a huge variety of traps, poisons and repellents commercially available, all claiming to be the answer to your problem. As these products will vary country to country, I will keep this advice on getting rid of mice as generic as possible and to be useful to the majority of people, wherever you may live.
Before we start getting rid of mice, we need to discover where they gained entry to the premises in the first place. Think of your situation as being in a boat that is leaking water – no matter how much or how quickly you bail the water out, the boat will continue to flood until you seal the holes. The analogy is the same with a mouse infestation. – no matter how many you catch in traps or poison, your home is at risk from re-infestation until you “proof” it against further ingress. Mice are notorious for squeezing through ridiculously small holes. Typical points of entry are through pipe runs (where pipes pass through external walls), beneath doors and through vents. Again, this is a subject all on its own and will vary with different building designs around the world, so getting rid of mice can involve quite a bit of detective work.
Did You Know?
The widest part of a mouse is its head. They can flatten their whole body to help squeeze through gaps as small as 6mm. So when hunting for their entry points, carry a biro (pen) and if you can fit the biro under a door, or through a hole in the wall alongside a pipe, then your furry friends can also squeeze through.
Start by looking in the area where the mice are most active. If this is in your kitchen, pay attention to the plumbing beneath your sink. Check for gaps alongside pipes, where they pass through the wall. If it is in your bathroom, you may need to remove any bath panel to be able to see where your pipes are running. Also look in any immersion heater cupboard and follow the pipework. An insulating jacket around an immersion heater is a perfect ready-made nesting location for mice – it is warm, dark and comfortable (and the rent’s free).
A telltale sign that mice are using a hole for access is a smear mark on the lip of the hole. This smear is from oil in the mouse’s fur and is a sure sign that the hole is in regular use. Smear marks can be found on any route, or “run”, in regular use by mice, so keep a look out for them. If you find any holes, with or without smear marks, seal them with any hard-setting filler. A good tip to help prevent mice from gnawing through the filler is to first mix it with a ball of wire-wool before filling the hole. If you can slide your biro under your external doors, you will need to install a bristle strip. These are often available from hardware stores, DIY retailers and online and are available in different lengths of bristle. They are simple to fit, just make sure that the strip covers the whole of the gap along the bottom of the door and that the bottom edge of the bristles lightly brush the ground. Most doors would need a strip with a bristle length of 15 – 20mm. If your door opens over an uneven surface, you can use a strip with a longer bristle (more flexible). In this situation, you would need to mount the strip slightly higher on the door to compensate for the extra long bristles.
How To Catch A Mouse
So now that you think you have found where the mice are getting in from (it’s not always easy to find this straight away, so some trial and error is likely but keep at it) and you have made plans for sealing up these points, you now need to eradicate your unwanted guests. If all evidence suggests that you have a small number of mice in your home, I would advise using mouse traps to catch and remove them. If you don’t like the idea of actually killing the mice, you can buy “live traps” or “humane traps”. If you do use these humane mouse traps and are successful in catching the mice, DON’T take them into your garden and set them free. They are not called House Mice for nothing. The clue is in the name! If you let the mouse free in your garden, it will spend the next few hours trying to get back inside and if you have followed my advice and sealed all entry holes, then it will try and get into your neighbors home and you won’t be very popular. So go and visit your local beauty spot and set him free there.
If you are less sentimental and are happy to help reduce the world’s mouse population, you should use “break-back” mouse traps (also called snap traps), see the images on this page for an example.
Again, there are many different brands of mouse traps available but they all follow the same basic design. This being a spring loaded wire arm that is released by a small pressure plate to snap down with force (enough to blacken your finger nail if you happen to trap yourself).
Mice are at the bottom of the food chain and happen to be short sighted. They will travel from A to B along a wall, hugging the skirting board or other flat surfaces. Break-back mouse traps should be positioned perpendicular to the wall, so that when sprung, the wire arm travels towards the wall. To improve the effectiveness of the trap, you can create a “run” or narrow passage by placing boxes either side of the trap so that the mouse is travelling along an alley. Make sure the “alley” is only as wide as the trap’s pressure plate. If you do this, it isn’t necessary to place food on the trap’s pressure plate as the mouse will have to run over the plate to reach it’s destination and you can trap it simply by interception.
If you don’t do this, you will need to bait the trap. DON’T use cheese. First of all, whilst mice will eat cheese, it’s because they will eat most things. However, cheese will dry and shrivel up after a few hours and become loose from the trap’s securing spike. When that happens, an inquisitive mouse is capable of removing it from the trap without putting enough pressure on the plate to set the trap off. I have found the best bait to be peanut butter. Other good ones are chocolate spread or bacon rind but most scraps of food will do.
Be sure to inspect your mouse traps regularly. You don’t want to leave a trapped mouse in the trap for any length of time. Whilst mice are not the smartest bunnies in the animal world, you don’t want to advertise what’s in store to the next one that steps on the plate. The force of the sprung arm is sufficient to kill the mouse instantly in most cases, however, on the few occasions when the mouse survives the initial “snap” it would be cruel to leave the poor thing stuck there for any length of time. To remove a trapped mouse, simply hold the trap over a waste basket and pull the sprung arm back. The mouse should fall away into the basket without you needing to handle it. Reset the trap and await the next capture. If you are failing to trap any of the mice, you will need to experiment with your locations and bait. Don’t set traps too close to each other or too close to any recognized hole. I have always had greater success with traps placed midway along a wall and always try to make an artificial run (alley).
If your home is well and truly infested, i.e. you have a resident mouse population that is reproducing and causing a lot of mess (evidence of infestation will include persistent sightings, visible droppings, a musty smell in the home, smear marks, damage from gnawing to wooden surfaces, cardboard boxes, textiles, etc), traps will be too labor intensive to be a practical solution. You will need to consider using a rodenticide poison. If you have small children or family pets, it is advisable to use a professional Pest Control Operator as they should be able to administer the bait in tamper-proof bait stations. If you are adamant that you are going to do it yourself, then you can usually purchase approved rodent poisons from hardware stores, DIY retailers and garden centers. Poison availability will vary from country to country but most come in the form of cereal or wax blocks. If you can buy them in ready-baited tamper-proof boxes, use those.
Most poisons available to the general public are multi-feed anticoagulants. This means that an individual mouse will need to nibble away at the poison bait for several days before it will have ingested enough to kill it. Enough bait will need to be used to ensure all the mice have access to it. Mice are territorial and have a hierarchy with an alpha male at the head (just like chimpanzees and other social groups), so if you use too little bait, the alpha and senior mice will eat all the bait, then die, leaving a gap for a new hierarchy to develop and you will be back to square one. You should positions small amounts of bait in several locations (little and often) and replenish it every couple of days. If there are young children and family pets in the home, make sure the rodenticide is placed where it will not be easily disturbed. A good idea is to cover the bait with an up-turned shoe box (be sure to cut a couple of “Tom & Jerry” holes in the box for access) and then place some heavy books on top of the box. Also, keep a note of all the bait locations and make sure all unused bait is removed once you have eradicated the mice. Depending on the size of the mouse population within your home, eradication may take a few weeks. As the poison starts to take effect, the mice will become lethargic and are likely to die close to where they are resting through the day, i.e. out of view. Being very small, most corpses will desiccate very quickly and shouldn’t present a smell, however, if a mouse dies close to a hot pipe or in a humid location there will be a risk that you have to deal with a bit of a pong.