House Mouse

Disney and others have given the common house mouse an image as the fast and clever neighbor who is harmless and only wants to share a bit of cheese before running back into his hole to feed his little family. Would that the real mice who harbor in San Diego homes and fields were so innocuous. Happily, they are also not that clever. Rats are much more intelligent than their smaller cousins, and although they do share many traits, managing mice is a bit different.

The house mouse is gray, and weighs one half to one ounce - tiny! Their bodies are usually 3-4 inches long, with a tail the same length. Large ears, small eyes, and a pointed muzzle typify the  mouse. A female house mouse can have around eight litters of six or more young. It takes only 35 days for the young females to reach sexual maturity. So populations can grow rapidly!

Signs of mouse infestation are less noticeable than rat infestations. Mouse droppings are smaller, rub marks less visible, and they holes they fit through much smaller. As noted in yesterday's blog, they can squeeze through openings around 1/4 of an inch in diameter. Like rats, mice are more likely to invade as the nights get colder, but unlike rats they are more comfortable living in close association with humans. Unlike another, closer relative, the deer mouse, house mice have not been found to carry  Hantavirus. However, they do contaminate our food and can cause damage to home wiring and other parts of the structure. So Mickey has to go.

Control can be difficult, both because of the size of the breeches mice can enter through and because of their rapid reproduction. Still, sanitation, exclusion and trapping can be effective in ridding houses of house mice. While sanitation alone will not solve an existing mouse problem, the lack of proper cleaning is sure to attract them. Keep garbage in tight fitting containers, try not to leave out pet food, and store dry goods in sealed containers. In exclusion, fill any hole where mice might enter. Steel wool is a good temporary barrier, but construction foam is also useful. Check places where pipes and wires enter the house, along the foundation of the house, and check weather stripping at the bottom of all doors. When using traps, if you are dealing with mice rather than rats, glue boards have been found to be most successful. A very tiny bit of peanut butter in the center of the board will help make the trap attractive. For a discussion of other baits, see Monday's blog. When placing traps, put them behind objects, close to the wall, and in a dark corner if possible. By way of note, there are several electronic devices advertised in magazines, which claim to keep mice at bay through Ultrasonic sounds or other means. Be aware that although mice may be initially frightened by these devices, they soon become familiar and will not be a permanent method of exclusion. Obtaining a cat with mouse hunting experience would serve you better.

One last word on rodents and compassion. Although cartoon rats and mice are adorable, and these rodents can make good pets if properly bred and contained, the mice and rats that invade homes in the autumn can bring diseases and should be excluded for safety reasons. If you find your home is infested with these vermin, contact Vector Control and/or a pest professional for help.