House mice are among the most common home-invading pests in the Bay Area. Small, adaptable, and capable of reproducing rapidly, a mouse problem can escalate from a single sighting to a significant infestation in weeks. Here’s an honest guide to dealing with them effectively.
Identifying House Mice
House mice (Mus musculus) are small — about 3–4 inches in body length with a tail of similar length. They are grayish-brown with a lighter underside, large ears relative to their body size, and small, bright eyes. They can squeeze through gaps as small as a dime.
Signs of mouse activity include droppings (smaller than rat droppings, tapered at both ends), gnaw marks, shredded nesting material in storage areas, and scratching sounds in walls or ceilings at night.
The Exclusion First Rule
The single most important step in mouse control is finding and sealing entry points. Without exclusion, any number of mice you trap will simply be replaced by new ones entering through the same pathways. Common entry points include:
- Gaps around pipes and conduits where they enter walls
- Gaps under garage doors and exterior doors
- Cracks in the foundation or sill plate
- Gaps behind appliances where plumbing enters walls
- Weep holes and vents without proper screening
Trapping: What Works
Snap traps remain the most effective and responsible trapping tool for mice. They should be placed along walls and in areas with evidence of activity (droppings, gnaw marks, grease trails). Placement matters: traps should be perpendicular to the wall with the trigger end against the baseboard.
Glue boards are not recommended — they cause unnecessary suffering and are less effective than snap traps in most situations.
When to Call a Professional
If you’re seeing ongoing activity despite trapping, or if you can’t locate or seal the entry points, a professional inspection is the right move. ATCO’s rodent control program includes thorough inspection, exclusion recommendations, and strategic trapping. Contact us for an assessment.