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Pests

The House Mouse

​The house mouse has short hind feet and a tail that's as long as the head and body combined. Although usually a dark grey, some house mice have light brown backs with light brown bellies. When fully grown, they weigh about 15 grams (½ oz.) and are 8 cm (3 in.) long.

Females have 6 to 10 litters a year. They have about 5 babies per litter. The house mouse usually lives for about 1 year.

What are their habits?

The house mouse usually enters a home in the fall and winter, looking for food and shelter. They enter through holes or gaps in doors, walls, and foundations. A house mouse can squeeze through a crack as small as 1 cm (smaller than a dime).

You often realize that you have a house mouse because you see droppings near food, under stoves, refrigerators, and under sinks. You may also find holes in boxes and bags that have food or garbage in them. Mice also cause damage by gnawing on insulation and building material, furniture, paper, clothing, and books.

Mice contaminate food with their urine, hair, and droppings. Food can become contaminated with germs like Salmonella. Mice also carry fleas, mites, and the disease Hantavirus.

How do I control them at home?

Keeping your house clean will help prevent mice from moving into your home. Once you know you have a house mouse, make sure to protect all food. Use glass or metal containers as mice can chew through plastic.

The best way to control a mouse infestation is by using several methods at the same time. This is called an Integrated Pest Management program. Both physical and chemical methods are used. You can also call a licensed pest control operator, especially if the infestation is bad.

Mouse proof your home by sealing the openings around pipes, doors, windows, and holes in walls, foundations, or other points of entry with steel wool.

How do I catch the mice?

Trapping is preferred when it's not safe to use poison baits. Don’t use poison baits wherever food, children, or pets are.

Several types of mechanical devices can be used to catch mice. Snap traps work well, causing an instant death. You have to make sure you bait and set the trap properly. Dried fruit, peanut butter, or marshmallows work very well as baits.

Another trap that works well is the ready-to-use glue board. When mice try to cross the board they become glued to the surface and eventually die. Glue boards are scented or can be baited (e.g., with peanut butter).

You can buy both types of devices in hardware stores. Put the glue boards and snap traps in corners and across the paths that mice use (mice prefer to travel around the edge of a room). Make sure you check them often.

If the traps don’t work, you might have to use poison bait. Most ready-to-use commercial baits weigh about 15 grams (½ oz.) contain a product that damages the mouse’s blood vessels and doesn’t allow the blood to clot. Death is caused by internal bleeding, which happens as the blood vessels are destroyed. The poison bait causes the mouse to dry up rather than rot. This means the dead mouse won’t smell.

Make sure poison baits are placed only where mice can get them. Keep them out of reach of pets and children. Follow the directions carefully.

How do I handle a dead mouse or droppings?

Assume all mice, traps, their droppings/urine, and their nests carry disease. Open windows and doors for 30 minutes to air out the infested area. When cleaning a heavily infested area, wear a respirator with an N-100 filter. Drug stores and hardware stores sell these respirators. Don’t dry sweep or vacuum the droppings and nesting material so that you don’t create any spray.

Dead mice, nesting material, and droppings should be soaked with a disinfectant or household bleach solution (1½ cups of bleach per gallon of water—1 part bleach to 10 parts water). Clean up the area with a wet paper towel. Use latex or rubber gloves or use a plastic bag as a glove when cleaning up or handling any items. Put the dead and trapped mice, nesting material, droppings, and cleaning material in a sealed plastic bag and put in a garbage container that is outside. Before you take off the gloves, wash your gloved hands in the bleach solution.

If you’re using an insecticide (pesticide), make sure to read the label closely. Chemical control works best when used with physical control methods.

When to Hire a Professional

If the problem is bad, it’s best to hire a certified pest control professional. Make sure they have a chemical application certificate. You can ask to see it or check with Alberta Environment and Parks by calling 1-877-944-0303.

The professional should be able to tell you what’s causing the pest problem and come up with a plan to get rid of the pest. Tell the professional if you have children or pets. Several visits may be needed and it may take days or even weeks if the pest problem is really bad.

If you rent, you landlord must, by law, keep the home pest-free and hire a professional as needed. If your landlord doesn’t correct the problem, call Health Link at 811 to register a complaint for a health inspector.

To learn more, call your nearest Environmental Health office.

Current as of: March 15, 2018

Author: Environmental Public Health, Alberta Health Services