Identify Your Pest Rodents House mouse
House mouse
Mus musculus
The house mouse is a small grey-brown rodent that lives alongside people in homes, garages and businesses. Most people notice it by its droppings, chewed food packages or scratching sounds in walls and ceilings at night.
Size 6 to 9 cm body, plus a tail about as long
Colour Grey to grey-brown back with a slightly lighter grey belly
Key feature Long, nearly hairless tail and large ears on a small, slim body
Season Year round indoors; most new entries happen in fall as nights get cold
Where Kitchens, pantries, wall voids, basements, garages and behind appliances
What it looks like
The house mouse is small and slim, with a pointed snout, large rounded ears and small dark eyes. Its fur is grey to grey-brown on the back and only a little lighter underneath. The tail is long, thin and almost hairless, and about as long as the head and body together. An adult weighs about 14 to 28 grams.
House mice are active mostly at night and stay close to their nest, often within a few metres. They climb well and can squeeze through gaps just over 6 mm wide. A stale, musky smell and small dark droppings along walls are common clues.
Often confused with
Deer mouse
Meadow vole
Young Norway rat
Signs to look for
Droppings
Gnaw marks
Night noises
Nests
Smell and smudges
Risks and damage
House mice spoil food and surfaces with droppings and urine, and they can carry germs such as Salmonella. Their droppings and dander can also trigger allergies or asthma in some people. Mice gnaw constantly, so they damage food packages, insulation, stored items and sometimes electrical wiring, which can become a fire risk. House mice are not known to carry hantavirus, but deer mice are, so clean up any mouse mess with care.
In Alberta
House mice live in cities, towns and farms across Alberta, including Edmonton and Calgary. Once inside, they can stay all year. Most homeowners notice them in fall, when cooler nights push mice from yards, sheds and fields into warm buildings to find food and shelter.
A house mouse’s front teeth never stop growing. Mice gnaw on hard materials every day to keep their teeth worn down, which is why they chew through things they cannot even eat.
How to keep them out
Seal gaps over 6 mm
Store food in sealed containers
Fit door sweeps
Cut the clutter
Tidy the yard
When it is time to bring in a professional
Call a professional if you see mice during the day, find fresh droppings in several rooms, or keep catching mice week after week. These can point to an established population. Technica’s licensed technicians can find entry points, remove the mice and help seal the building to lower the chance of mice coming back.
Frequently asked questions
How do mice get into my house?
Mice follow warm air and food smells to small gaps. Common entry points are gaps around pipes and cables, worn door sweeps, garage doors, vents and cracks in the foundation. A mouse can fit through a gap just over 6 mm wide, about the width of a pencil.
If I see one mouse, are there more?
Often, yes. House mice breed quickly. A female can have several litters a year, with about five or six young in each, and the young can breed within 5 to 7 weeks. If you see one mouse, check nearby rooms for droppings and other signs.
How do I clean up mouse droppings safely?
Let fresh air in first: open the windows and doors, then stay out for half an hour. With rubber gloves on, soak the mess with a mix of 1 part bleach and 9 parts water and give it 5 minutes. Lift it with paper towel, bag it tightly and wash up. A broom or vacuum stirs up dust, so skip both.