How does a rodent get into the house and what will it do once it gets in?
Rats can wiggle their way into gaps and holes as small as a 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 other buildings. And the more food and water they can find once they are inside, the more likely it is that the population will quickly grow.
It can be quite unpleasant and disgusting to see a rat or mouse in the house, but even worse than that, rodents can cause damage with their gnawing, nest-making, and urinating, and they also can spread disease.
Once a rodent gets into a home, it will:
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 drop its feces along its path - contaminating everything along the way. 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, with teeth that are very sharp, enabling it to chew through boxes and bags you may think are safe.
Once a rat or mice gets into the food, it can 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 such as 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.
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 base of a potted plant; or even in a slow-draining tub or sink.
You may wish that it were only an old wives' tale but 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 Rodent 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 7 litters in 1 year, with up to 14 young in each litter. Rats are full-grown in about 4 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 6 young in each litter. (But there can be as many as 12 mice in a single litter!) They are full-grown to adulthood within 7 weeks, so, again, if conditions are ideal, a mouse population can explode in just a few months.