Mice are the most common pest call we get in Philadelphia, and for good reason: rowhomes, twins and older brick houses are full of small gaps that lead straight into kitchens and basements. The good news is that mice follow predictable patterns. Once you know how they get in and what they want, you can stop them.
This guide covers the signs to look for, what you can do yourself and when it makes sense to bring in a professional. If you already know you have a problem, our rodent control service handles inspection, sealing, trapping and follow-up for you.
Signs you have mice
- Small dark droppings, about the size of a grain of rice, in cabinets, drawers or along baseboards
- Scratching or scurrying sounds in walls or ceilings, usually at night
- Gnawed corners on food boxes, bags or pet food
- Shredded paper, fabric or insulation tucked into quiet corners
- Grease or rub marks along walls, pipes and baseboards where mice travel
How mice get into Philadelphia homes
A mouse can squeeze through a gap about the width of a pencil. In city homes, the most common entry points are gaps around gas, water and cable lines; cracks in old foundations and basement walls; openings under back doors and garage doors; and spaces in shared walls between rowhomes.
That last point matters. In a row of attached homes, mice move between basements and wall cavities. You can do everything right inside your own house and still see mice if a neighbor has an active problem. That is why sealing your side of shared walls is so important.
Step 1: Remove what they want
Mice come inside for food, water and shelter. Cutting off food is the fastest way to make your home less attractive.
- Store cereal, grains, snacks and pet food in sealed glass, metal or hard plastic containers
- Wipe up crumbs and spills at the end of each day, including under the stove and toaster
- Don't leave pet food out overnight
- Keep trash in lidded cans and take it out regularly
- Fix leaky pipes and dripping faucets, especially under sinks and in basements
- Reduce clutter in basements, closets and storage areas where mice can nest
Step 2: Seal entry points
Walk your basement and the outside of your home with a flashlight. Look anywhere a pipe, wire or vent passes through a wall, and anywhere you see daylight. Steel wool packed into small gaps and topped with caulk works well because mice cannot chew through it. Larger openings need hardware cloth, metal flashing or mortar. Add door sweeps to exterior doors.
Don't seal holes while mice are still nesting inside unless you are also trapping, or you may trap them in your walls.
Step 3: Trap the mice already inside
Snap traps are inexpensive and effective when placed correctly. Set them along walls, behind appliances and in places where you have found droppings, with the trigger end facing the wall. Mice run along edges, not across open floors. Use a small amount of peanut butter as bait, and use more traps than you think you need.
Check traps every day. If you have children or pets, use enclosed trap boxes so the traps are out of reach.
What doesn't work
- Ultrasonic plug-in devices: mice quickly get used to the sound
- Peppermint oil alone: it may keep mice away from one spot for a short time but won't solve an infestation
- Poison without a plan: loose bait can be dangerous to pets and children, and mice may die inside walls
- Sealing without trapping, or trapping without sealing: you need both
When to call a professional
Call a professional if you are still seeing mice after two weeks of trapping, if you find droppings in several rooms or floors, if you hear activity in walls or ceilings, or if you live in a rowhome where the problem keeps coming back from next door.
A professional inspection finds entry points that are easy to miss, like gaps behind a water heater or around a sewer line. At Northeast Exterminators, we start with a thorough inspection, seal entry points, place traps and secured bait stations, and come back to monitor until activity stops. If pests return within our guarantee period, we re-treat at no cost to you.
Keeping mice out for good
Mice are most likely to move indoors in the fall, when temperatures drop. A quick check of your foundation, doors and utility lines each autumn goes a long way. For homes that have had repeat problems, a quarterly service plan keeps monitoring in place year round so small problems never become big ones.