5 Signs You Have a Mouse Problem (Before You See One)

Most homeowners don't realize they have a mouse problem until they spot one running across the floor — and by that point, there are almost certainly many more hiding in your walls, attic, or basement. In Bergen County, mouse activity tends to spike in late September and October as temperatures drop and rodents start looking for a warm place to overwinter. Here are five signs to catch the problem before you ever see one in the flesh.

1. Droppings Along Walls and in Cabinets

Mouse droppings are small (about the size of a grain of rice), dark, and pointed at both ends. You'll typically find them along baseboards, inside kitchen cabinets, behind appliances, and in the back corners of pantries. Fresh droppings are dark and moist — older ones turn gray and crumble. If you're finding fresh droppings, you have an active infestation.

2. Gnaw Marks on Food Packaging or Wires

Mice gnaw constantly — their teeth never stop growing, so chewing is how they keep them filed down. Look for chew marks on cereal boxes, bags of rice or pasta, wooden furniture legs, and electrical wiring. Chewed wires inside walls are one of the leading causes of house fires attributed to rodents, so this isn't something to put off.

3. Scratching Noises at Night

Mice are most active between dusk and dawn. If you're hearing scratching, scurrying, or squeaking sounds inside your walls or ceiling at night, that's a strong indicator. This is one of the most common complaints we hear from homeowners in Fair Lawn and Hawthorne in the fall — especially in older homes where gaps in the foundation or around utilities are more common.

4. Nesting Material in Hidden Areas

Mice build nests from shredded paper, insulation, fabric, and other soft materials. Check behind water heaters, inside seldom-opened drawers, in the back of storage closets, and in the attic. A nest looks like a loose ball of shredded material — if you find one, assume the mice are still using it.

5. A Musky, Ammonia-Like Odor

Mouse urine has a distinctive musky smell. In heavily infested areas — particularly enclosed spaces like closets, cabinets, or crawl spaces — the odor can be noticeable even before you find droppings or signs of gnawing. If a room suddenly smells "off" and you can't identify why, it's worth investigating.

What to Do If You Find These Signs

• Don't just set a trap and hope for the best — find and seal entry points first, or more will replace the ones you catch.
• Common entry points include gaps around pipes, dryer vents, and where utility lines enter the home. Older homes in Glen Rock, Hawthorne, and Fair Lawn often have more of these vulnerabilities.
• Mice can squeeze through a hole the size of a dime — sealing requires steel wool, caulk, or hardware cloth.
• Call a professional for a full inspection if you're finding multiple signs — DIY often addresses the tip of the iceberg.