Deer Mice

Visually, deer mice resemble  deer, two-toned with dark to light brownish colouring on the back and white colouring on the legs and underside. The tail is also dark on top and white underneath. They have large ears and eyes, but small feet. They range from 12 cm 20 cm in length and generally weigh less than 30 grams.

Habits & Behaviours

Deer mice are especially dangerous to humans because they can spread the potentially fatal hantavirus. The virus can be spread by touching infected mice or by breathing in the dust from their feces. Deer mice can be found throughout Ontario and are active all year round. They are nocturnal and are rarely seen in their outdoor habitat. They often construct nests in hollow logs or tree stumps, under logs and stones, around fences and structures, and occasionally in bird nests and vacant burrows.

Deer mice are rarely a major problem in urban residential areas but if you reside or run a business in a rural or semi-rural area, there is a always the possibility that deer mice could enter and infest your residential, recreational/cottage, or commercial properties. Once they nest inside a property, they have a tendency to become quite annoying and troublesome, getting into stored food and polluting many areas throughout a property with urine and feces.

Complaints & Destruction

Although they are most commonly found in rural areas in open fields, grasslands, forests, and croplands, if deer mice infest your residential, recreational/cottage, or commercial property, they can be extremely difficult to exclude and are capable of doing considerable damage to the interior and exterior of the property.

They will nest in attics, wall cavities, garages, crawl spaces, storage areas, and even in pantries, cabinets and drawers. A deer mouse can squeeze through a hole the size of a coin and will gnaw and tear through almost anything in search of food and shelter.  Constantly searching for food and nest material, deer mice will destroy and shred various materials, including fabrics, wood, wiring, cables, furnishings, food containers, and insulation.  A deer mouse will consume small amounts of food several times day, but will destroy a considerable amount more than they eat, contaminating it with feces, urine and fur. In  rural, agricultural areas, they are capable of destroying massive amounts of food.

Major Risks & Dangers

Fires, electrical issues and power outages

Deer mice will chew electrical wiring and cables, which may result in costly repairs, power outages, and a serious risk of fire.

Structural and home efficiency damages

Deer mice will gnaw constantly in search of food, to gain access to properties, and to prevent their teeth from growing too long. This damage can destroy household appliances and cause costly structural damages and higher energy costs. In addition, these openings can make it easy for other nuisance animals to gain access to the property.

Health risks

Deer mice are especially dangerous to humans because they can spread the potentially fatal hantavirus. The virus can be spread by touching infected mice or by breathing in the dust from their feces. Deer mice are a major health and safety risk in homes and businesses. They can contaminate food and various areas/materials with feces, urine and fur. They can spread other diseases such as salmonella, lepospirae and typhus and carry various parasites such as fleas, round worms, and mites that can transmit diseases to humans and domestic pets. Dead and decomposing deer mice can infect drinking water, attract insects, and cause staining and putrid odours that can last for months.


Deer mice can mate all year round and reproduce based on food supply and favourable climates, but more of than not, do so in the spring and fall. One female deer mouse can have 4 to 6 litters per year. The average gestation period is 21 days and the average litter consists of 3 to 9 young. The young mature very quickly and reach sexual maturity at about 6 and 8 weeks old.

Eating Habits

Deer Mice are omnivores and although they prefer seeds, grains and vegetation, will eat just about anything.


To reduce the risk of deer mice invading and destroying your residential, recreational/cottage, or commercial properties, exclusion is the best prevention.

Greenshield Pest Control Inc. can provide you with many exclusion solutions including:

  • Exclusion proofing and blocking off potential access points.
    • Repairing holes and rotting or damaged materials and structures.


Deer mice are extraordinarily resilient and properly eliminating them requires knowledge of and experience with mice and their habits. If you suspect that deer mice may be dwelling in or on your residential, recreational/cottage, or commercial properties, it is best to let the professionals do the job of safely and humanely removing the animal(s). Please contact us today or see our Pest Control Services section for further information on the types of services and solutions we can provide.

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