Symptoms
- Mouse seen running across a room, kitchen, or garage
- Sighting often at night or when a light is suddenly turned on
- Sometimes accompanied by droppings or gnaw marks elsewhere
Likely causes
- CommonAn established nest nearby with more mice than the one seenMice breed quickly, so one seen mouse often means several more are present.
- CommonRecent entry through an unsealed gapA single new mouse can get in through even a small unsealed opening.
- PossibleFood or shelter drawing it deeper indoorsOnce inside, an accessible food source keeps a mouse from leaving on its own.
What to do
- Stay calm; a single mouse sighting doesn't need an emergency reaction, but should prompt quick action.
- Set several snap traps or bait stations in the areas where it was seen and along walls nearby, since mice travel along edges.
- Remove accessible food sources, including pet food left out overnight.
- Walk the exterior and interior looking for likely entry points, such as gaps around pipes, vents, garage doors, or foundation cracks.
- Seal any found gaps with steel wool, hardware cloth, or caulk as appropriate for the size and material.
- Check traps daily and dispose of caught mice with gloves, then clean and disinfect the area.
- Call a pest control professional if you see more than one mouse or signs continue after a week or two of trapping.
Tools and parts
- Gloves
- Flashlight
Snap trapsSearch: “mouse snap traps”
When to call a pro
Call a pest control professional if trapping doesn't resolve it within a week or two, or if multiple mice are seen.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.