The Garage Can Provide a Gateway to the House
Mice often first enter a structure by way of the attached garage. And why not? It's easy to get into a garage and it provides a perfect staging area while contemplating a final push into the house itself.
What Attracts Mice to Garages?
The attraction might seem obvious. Garages are rarely well-sealed, and even if unheated, they provide some protection from the elements. Often there is not even room for a vehicle, so disturbance is at a minimum. But there has to be some promise of food to entice a mouse to set up housekeeping in a garage. If you ask your customers whether there is any food in the garage, they would probably reply in the negative, not realizing that all of the following provide food for mice:
pet food - bags, boxes, or bowls of dog or cat food are a major enticement to mice
garbage cans or bags - food garbage may be held in the garage prior to placing it at the curb or taking it to a facility
recycling containers - "empty" food or drink containers awaiting recycling provide enough leftover food residue to feed mice
birdseed - bags of birdseed for feeders are a favorite food of mice
bulk produce - boxes or bushel baskets of potatoes, onions, apples, or other harvested produce may be sitting on the floor or on a shelf
kitty litter boxes - mice might feed on cat poop or on kitty litter made from plants
gardening supplies - seed packets, bulbs, grass seed
Besides warmth, shelter, and food, another factor that attracts mice to garages is clutter that provides hiding and nesting sites. Some garages have neater clutter than others but all have stored items, boxes, shelves of "stuff" stacks of papers or rags, etc. Much of the clutter also provides soft nest material for female mice.
How Do Mice Get Into Garages?
There's no doubt that garage doors are the primary entrance point for mice. Because of the nature of garage doors, it's rare to find one with any age that seals tightly enough at all points to keep mice out. Look for light leaks along the edges, in the corners where the rubber threshold at the bottom meets the side walls, and maybe even under the worn bottom rubber gasket. Where you see light gaps, mice see opportunity.
Don't expect invading mice to stay in the garage for any length of time, especially if it's a busy place. From the garage, they can follow pipe chases or electrical or cable runs that enter wall voids or the attic. They can get into the houses through laundry drains, vents, utility runs, furnace ducts, or an attic access opening. And of course, there's always a single door into the house that may remain open or seal poorly.
Prevention of Garage Mice - Advice for Customers
Replace gaskets and rubber thresholds, and otherwise rodent-proof the garage door.
Store pet food, birdseed, grass seed, grains in heavy containers with tight lids.
Don't leave pet food in bowls in the garage overnight.
Store garbage and recycling in containers with tight lids.
As much as possible, keep boxes and items up on shelves and off of the garage floor.
On the outside: avoid stacking wood, brush, or other attractions for mice near the garage. Move garbage cans, recycling bins, and pet bowls away from the garage door.
Allow pets access to garage. Cats are great deterrents to mice but don't forget to clean the litter box regularly.
Control of Garage Mice
Avoid the use of rodenticide baits if children and pets have access to the garage and also because mice can so easily move into voids to die and smell. At first, use lots of snap traps and lots of food bait, or use multi-catch traps. Place traps along runways and edges. In a cluttered garage, move items on the floor to create new runways (and trapping spaces) that are accessible. If pets or children enter the garage, place traps inside tamper-resistant bait stations. Seal any gaps where utility lines enter, pipe chases, and other openings from the garage into the house or attic. Consider placing tamper-resistant bait stations on the outside of the house at each corner of the garage door where mice usually enter.