House mouse (Mus musculus) in New Zealand

Introduce / invasive rodent to New Zealand.

Found worldwide, adapts well to most climatic conditions. In New Zealand the house mouse can be found virtually anywhere that humans are living.

House mice fit into small spaces and can enter buildings through tiny gaps in foundations, around doorways and garages. Once inside, mice build nests in hidden areas near food sources. Homeowners may also find them living in attics, wall voids, under cabinets or inside crawl spaces.

The house mouse is a prolific breeder and a female can have 6-8 young in a litter and five to ten litters per year depending on availability of food.  Lifespan in the wild is about 12 months, but domestic pet mice may live up to three years.

Colour: Brownish-grey above, white to grey or pale yellow below; soft dense fur to 7 mm long.

Size range (adult):  the body is 7-10 cm with a tail length of 5-10 cm. Weight is typically around 40 g.

The house mouse has bulging eyes in a small head with large rounded ears. They have a scaly tail about the same length as the body.

House mice are omnivores. In the wild they feed upon seeds, roots, leaves, stems and other plant material, supplementing this with insects such as beetle larvae and caterpillars. An adult will eat about 3 g of food in a day.

• A house mouse can produce 50-75 droppings per day, droppingsare about 6 mm in length. The droppings are narrow cylinders with pointed ends. Colour varies depending on diet.
• Because they breed quickly and contaminate their food source during feeding, they can cause devastating damage to farms and crops.
• They will always look for a ready food and source along with warmth and shelter.
• If these are readily available, then a house mouse will not travel any great distance, mice will normally not travel further than 10 m from their harbourage, and can live entirely within a secure position such as a pallet of foodstuff.
• House mice do not require water as they can get sufficient moisture from their food.
• They will commonly use the same pathways from harbourage to food sources, leaving rub marks, urine trails and droppings to indicate these pathways.

House mice can sometimes transmit diseases, contaminate food, and damage food packaging. Only a few of the diseases transmitted by rats are transmitted through the house mouse, specifically Salmonella and Leptospirosis.

Good housekeeping is key preventative action to reduce the likelihood of a house mouse infestation.

In order to prevent mice from entering a property, all cracks, openings and holes should be sealed with metal or cement. All doors and windows must close properly. Foods should be stored in glass or metal containers with tightly sealed lids. All food waste should be removed  as soon as possible. For commercial accounts, incoming foodstuffs should be inspected to ensure that mice are not being introduced to the property.