Mouse in the house | What are the signs of infestation?

Rodents, ah! What a nightmare! Like their rat friends, mice seek food and a warm shelter. Without knowing it, we provide them with everything they need and that is why they like to stay close to humans for as long as possible.

A mouse infestation is usually not detected until very late because mice love hiding and during the day you will hardly ever see one. Great vigilance is therefore required. If you have a mouse invasion, time is of the essence, and that's why you need to be able to recognize and detect signs of an infestation quickly.

What do mice look like?

Typically, a house mouse is 3 to 10 cm long and weighs 12 to 45 g. What sets it apart from rats is its slender tail covered in hair and its ears, which are vastly larger than its head. Mice are covered with short hairs which are slightly lighter on the stomach.

Mouse extermination

How do mice get inside homes?

During a mouse infestation, the first thing you have to do is identify the entry point where the mice get inside your home and close that access point. This will not solve the infestation immediately, but it will prevent the mice from coming back again and again.

Mice can enter the house from:

• An opening in the exterior walls (upright joints, ventilation holes, etc.) 
• An opening under a door (garage door, entrance door, back door, etc.)
• A window that is not well framed
• The vegetation around your house, which they manage to climb to get inside
• Sewers
• Openings in the foundation of the house
• Heating or air conditioning ducts, around which we usually leave some space. It's the perfect network for mice to roam around the house.
• A gutter

What problems can they cause?

Rodents invade many homes each winter, and an infestation can cause more than a headache for homeowners since mice can spread disease and cause severe damage once inside. They can seriously damage buildings and even cause fires by gnawing at electrical wires.

The accumulation of mouse droppings can spread bacteria, contaminate food sources and trigger allergic reactions in humans. Once the stools are dry, they can be dangerous for those who inhale them. Rodent droppings can spread diseases and viruses (salmonellosis, bubonic plague, hantavirus, etc.) so it is important to react quickly and contact a professional mouse exterminator.

Signs of a mouse infestation

When you hear scratching noises in the attic or false ceilings, or when you notice gnawed corners or nibbled objects, it is possible that a mouse infestation is the reason. Mice multiply quickly even if they are only passing by so it is important to know how to detect the first signs of infestation quickly to prevent the situation from getting worse.

1. Mouse droppings 

The presence of feces is the best evidence of a mouse infestation. On average, mice do 50 to 80 droppings per day. They are scattered all over the house since mice move around a lot and feed in different places. The droppings have an elongated shape and are around 3-8mm long.

Fresh feces are dark and moist. As they age, they dry out and turn gray and crumble easily to the touch. Excrements make it possible to detect the places where mice wander around, feed and live. This is why they are most often found near food packages, in drawers or cupboards, under sinks, etc. You will find the greatest number of droppings where mice nest or feed.

2. Nibble marks

Besides feces, gnawing damage is the second most important indicator to identify a mouse infestation. Mice must be careful to continually shorten their teeth so they gnaw on different materials to sharpen their teeth.

Mice eat almost anything: furniture, baseboards, walls, ceilings, foundations, floors and electrical cables. Nibble marks usually consist of two parallel grooves 1 to 2 mm apart. Act quickly when you notice nibble marks because mice can potentially bite power cables and start a fire.

3. Musky odor

Mice emit a strong, unpleasant odor, which is especially noticeable in enclosed spaces, such as closets or sealed attics. The odor comes from the urine or ammonia produced by the mice. This smell helps them orient themselves and mark their territory. Each family of mice has its own unique scent, which allows them to recognize each other.

Pets are very good at detecting rodent scents, so if you see your pet pawing in an area they previously had no interest in, take a closer look at the area. If the smell is really prevalent, you could have a heavy mouse infestation on your hands.

4. Grease marks and mouse tracks

If mice are currently active in your home, their tracks are likely to be detectable. Mice usually follow the same route and frequently pass through the same places so they often rub their greasy coat against the wall or the floor, leaving dark greasy marks on their path. 

Other traces that mice are likely to leave in their path are their footprints (visible on the dusty floors of attics or cellars). However, this is still an unreliable indicator so to know if you currently have an infestation, make sure to clean the surface and place a very thin layer of flour or talc. If the mice are active, you will likely see new trails in the powder.

5. Scratching noises

Mice are generally most active just before sunrise or just after sunset. They are very curious animals, and because of their poor eyesight, they depend entirely on their sense of smell, touch and hearing. Therefore, if you hear scratching noises in the morning or evening, it is most likely hungry mice looking for food.

Mice are good climbers, they can move from one floor to another without any problem through walls. So you can potentially hear scratching noises in the walls, false ceilings and the attic.

6. Mouse nests

Mice are small rodents that like to live in groups so you will rarely find them alone. Due to their small size and their ability to climb and squeeze in small hollows, they can nest almost anywhere. However, they prefer quiet places, protected from light and with a nearby food source (attics, walls, etc.).

Unlike rats, which need a nearby water source, mice don't need that much water. They can survive by consuming the water from the food they find. Mice use whatever they find as materials to build their nests (paper, fabric, branches, cardboard, dried plants, etc.).

How do you get rid of mice?

Preventive measures

It is often said that prevention is the best medicine, this is even more true when it comes to a mouse infestation. Here are some tips to help prevent mice from infiltrating your home:

• Eliminate easily accessible entry points by ensuring that the metal weatherstripping under doors are in good condition and by caulking windows
• Seal cracks in foundations or walls
• Cover the ventilation ducts of the dryer with a fine wire mesh
• Eliminate potential nesting sites around your home and garage
• Cut tall grass and weeds near your house
• Put your waste in closed containers
• Keep your kitchen clean
• Store food in containers with a tight-fitting lid

Physical intervention

If you are facing a mouse infestation, one of the first thing to do is set up traps to attract mice. Whether they are spring traps or electronic traps, they are easy to handle and very effective when placed in the right place.

These traps usually kill mice instantly or are triggered when the animal steps on them. However, before using a trap, here are some guidelines to follow:

• Install your traps at right angles to a wall
• Place the traps without engaging them for the first 3 days so that the mice get used to them. That way, they won't hesitate to grab the bait when the traps are finally set
• Use strong smelling foods that are sticky (peanut butter, bacon fat, etc.)
• Reuse traps
• Check your traps every day

Products to use

To combat a mouse infestation, you can also use poison baits, lining the outside with a repellent to prevent new mice from entering, but also placing them in areas of the house suitable for nesting. However, mouse poisons or repellents are not harmless.

It is recommended that you hire a pest management service to get rid of your infestation safely and effectively. Please do not hesitate to contact us if you have any questions or would like more information about our services.