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How Does a Mouse Get In the House?

Facts About Rats and Mice


How Does a Mouse Get In the House?
by George Shuklin

Rats can wiggle their way into gaps and holes as small as ½ inch. And if the hole is not yet ½-inch big, the rat can gnaw at it until it is. Mice can squeeze in through holes as small as ¼ inch. And, like rats, mice will chew and gnaw at smaller holes until they are big enough to wriggle through.

Additionally, both rats and mice prefer warmth over cold. This means that when the weather outside starts to turn cold, rats and mice will turn to houses and buildings (especially restaurants and hotels that are likely to have lots of good food and water sources for them as well) to make their homes.

Few people want to have rodents in your homes (or in restaurants or hotels you visit!), but did you know that the rodents are not just pests, they can cause significant damage and also spread disease.

Once a rodent gets into a home or building, it will:

  • Make its nest. Using whatever is at hand - a pile of old newspapers, clothes or fabric stored in cardboard boxes that it easily chews into, stacks of magazines or even important files - it will chew the items into shreds then bunch it around making a nice, soft comfortable nest.
    Rodents will also chew on other items - such as drywall, insulation and wiring, not only causing significant damage to your home, but also potentially causing a fire to ignite from the bared wires.
  • Search out food. Before or after making its nest - depending on how hungry it is - the rodent will roam your home in search of food. As it roams, it will urinate and drops its feces along its path - contaminating everything along the way.
    And if it makes its way to your pantry or other food storage area, it is likely to walk on the food and food packaging, so that next time you touch it, you are touching its urine trail as well.
    Rodents will chew through the packaging to get to food, and the rodent's teeth are quite sharp enabling it to chew through boxes and bags you'd think were safe.
    Rodents that do get to your food can also be the source of foodborne illness, such as salmonellosis, which is transmitted when a person eats or drinks food or water that is contaminated by rodent feces and causes diarrhea, fever, and abdominal cramps. According to CDC, certain rodents can also directly transmit diseases to humans, including Hantavirus Pulmonary Syndrome, Hemorrhagic Fever with Renal Syndrome, Lassa Fever, Leptospirosis, Lymphocytic Chorio-meningitis (LCM), Omsk Hemorrhagic Fever, Plague, Rat-Bite Fever, Salmonellosis, South American Arenaviruses, and Tularemia.
  • Seek water. Rodents need water to survive. Some foods will provide them with some water, but they will also need free water … such as the water in the bowl left on the floor for your cat or dog; in the planter base; or even in a slow-draining tub.
    And, while you may wish that it were only an old wives' tale, it is true that rats can swim through sewers and come up through toilet bowls or other drains. It is not a common occurrence, but it can happen.
  • Make babies. Rodents are prolific breeders, so populations can build very quickly in a home or building if the rats or mice have sufficient food, water, and shelter.
    • Rats: Each female can have up to seven litters in a year, with up to 14 young in each litter. Rats are full-grown in about four weeks, which means that quite a few generations can be born in a single year - from each female of the litter.
    • Mice: The house mouse can have up to 10 litters in a single year with about six young in each litter. (But there can be as many as 12 mice in a single litter!) They are full-grown to adulthood within seven weeks, so, again, if conditions are ideal, a mouse population can explode within the space of mouths.

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