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What Are The Signs of a Mouse Infestation?

Infestation on its own is not a word people love to hear. A mouse infestation adds at least 10 horror points to the situation. You see signs everywhere and little mice shadows start to follow you behind every corner. Leaving the panic aside, seeing a mouse is one of the sure ways to determine that you have an infestation but this may still not be enough. In the article below, we will show you what signs you should look for, what are the reasons for an infestation, how to prevent it and how to take care of it if it’s already a fact.

Signs of a Mouse Infestation

When in doubt of a mice infestation, you have to look for other indications. We have prepared a list for you with all the signs you have to pay attention to and how to recognise which is which.

  • Mice droppings - A sure sign that you have mice is if you notice their droppings, but you have to know how to recognise them. Usually, there could be from 50 to 80 droppings a night, dark and moist in the beginning; dry and grey when they get older. Each is around 3-5 mm in diameter. You can find them around food sources and the more they get, the closer you are to their nest.

  • Mouse footprints - Those little tracks are most visible in dusty environments like lofts, attics and basements. If you have doubts about having a mouse in your house, just lay down some flour on the floor around your kitchen cabinets, for example, and check the surface on the next day or the day after.

  • Grease marks - Unlike rats, mice do not leave any grease marks when brushing off against walls and other surfaces. Although not the cleanest of animals, mice are really light in weight, flexible and can squeeze through the smallest of openings without leaving any traces. So, if you happen to see such, maybe you have a rat problem after all.

    Learn the difference between mice and rats >


  • Urine puddles - Mice urinate a lot and just like the droppings, you are more likely to find puddles closer to their nest.

  • Scratching noises - During the night, mice are very active and most of their adventures, when scavenging, occur while we are sound asleep. Listen for different noises like scratching and steps coming from inside the walls, around cabinets, lofts, attics and false ceilings.

  • Mice nests - Finding a nest is a sure way to determine if you have an infestation at hand. If the mice have already gotten to the point to have an organised, structured nest, then surely their number is not low and your home is also their home. Always be on a lookout for potential nesting locations, such as cabinets, the inside of walls, behind electrical appliances and suspended ceilings.

    Read about mouse nests >


  • Mouse sightings - Mice are nocturnal creatures, so they are most likely to be active and come out of their hiding during the night. They go out searching for food and nesting material when everyone is sound asleep. Saw a mouse during the day? If you do happen to see a mouse in broad daylight, then, probably the infestation is getting already out of control and you will need the help of a professional pest service.

  • Mouse smell - Mice urinate a lot and most of the time they urinate close to their nests, as we mentioned earlier. This smell is a mixture of mouse pee, droppings and ammonia. The stronger the smell is - the closer you are to a nest.

How to Check for Mice?

If you have doubts about a mouse infestation in your property, following the signs above, you will be able to determine whether there is one or not. It's really important as well to understand which are the most likely mice nesting locations. The rodents use their very bendable skeletons to squeeze into very tiny spaces, so when you are on the lookout for a mouse, be sure to check out these places.

  • Lofts, attics & eaves - Most of the material that mice use for nesting is hidden in your loft or attic, probably stuff that you’ve stored away for winter or summer time, depending on the season. Every box, piece of fabric and loft insulation is a perfect building material. Check if they are chewed, gnawed and damaged and always try to scent the ammonia smell of their urine.
  • Kitchen cupboards and electrical appliances - One of their favourite place for nesting is in your kitchen, as they'll try to be as close to the food as they could. The lower cupboards are very often their prime choice, so be sure to check all of them. Unfortunately, the pests usually manage to cram themselves behind your electrical appliances and chew all the cables, again, searching for nesting material. It's really important to check all of them, mostly for your safety.
  • Basement and cellars - Similar to the attics, mice will find an entry point to your basement or cellar without breaking a sweat. A broken vent or air bricks are more than convenient for their tiny bodies to go through.
  • Cavity walls - Any space that is tiny, dark and hidden is a perfect place for a house mouse to settle in. Suspended ceilings, under the stairs, crawl spaces and airing cupboards very often go unnoticed and mice manage to build their nest and colony with no problem. You can find more info about what to do when you have mice in your walls below.

If you can hear tiny steps, screeches and scratches, you probably have mice in your walls. You can take care of them by placing a food-scented snap trap along the bottom edges of the wall. It's important to get them out and get rid of them after that, instead of placing poison and leaving them to die somewhere in the walls.
Another way to attract mice to get out of your walls is to drill a small hole with the size of a coin in the place you think they are most active. Drill the same hole on the side of a cardboard box and place the latter, so it’s adjacent to the wall. Put some food in there, like peanut butter, for example, so you can tempt the vermin to get out of their hiding place. It would be better if you can see when you have caught a mouse, so to be able to do this, you have to remove the top part of the box and replace it with a transparent cellophane. You should have your first mouse in the next hour!
After you have lured all the mice out of the walls, make sure to block all entries to your house, from inside and outside, as well. You can use mesh wire and plasterboards to seal the holes you need to.

In order to determine whether you have mice outside your house, you have to check the following locations.

  • Sheds - Sheds are basically like mini-houses and very often a place where we may store pet food, bird food or keep other stuff that is attractive to the rodents. Mice can find whatever they need for their nests and well-being in a shed, so check the space thoroughly.
  • Garages - One of the places mice love to make nests are the engines of our cars, so make sure you check it for signs of nesting. In any case, the garage is a very good place for the mice to prosper with its many hiding places and nesting materials.
  • Compost bins - They are perfect for mice as they are comfy, full of food and hidden. Check your bins for gnaw marks and scratches on the lids.
  • Vegetation - Overgrown plants make a very good shelter for mice as they provide food and nesting materials at the same time. Also, they are in places people rarely check for infestation and so the pest problem often goes unnoticed.

How to Confirm There is a Mouse Infestation

To confirm that there is an infestation in your property, you have to look out for all the signs mentioned above at all possible locations. Even though the best way to decide if there is an infestation or not is to actually hire a pest control technician, who knows what to look for, you can make a couple of simple tests on your own:

  1. The flour test: pour flour on the most used mice routes and check how many tiny steps you can distinguish. The prints don’t actually look like prints, but more like dots, spread out on the floor. They are around 0.5cm long and very close to each other.
  2. The biscuit test: mice will never refuse an easy snack, so just leave a cookie outside for the night. In the morning, check if the biscuit is still in one piece. You can also use this method to determine whether you have mice or rats. Mice will only gnaw on the cookie until they are full and leave after. Rats will take it with them, to store for the winter.

Is One Mouse a Sign of an Infestation?

A mouse on its own is not an infestation but considering the speed at which they reproduce, a single mouse could be a big problem. First and foremost, they are not lone creatures, so they travel either in packs or at least in couples. One female can produce up to 10 litters a year with 6 pups in each of them. Each mouse needs around 2 weeks to reach reproductive age and will continue giving birth at the same speed. Even if by any chance you have only one mouse that has got lost and is not a part of a nest, it’s still a problem. It could still inflict a lot of damage to your property and leave around 9000 droppings a year. A number of serious problems come from these small creatures, so do not calm yourself with the fact that you don’t have an entire nest and quickly take care of the issue, as soon as you sight the pest.

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