Why Rodents Cannot Stop Gnawing and What It Is Doing to Your Home

You find a hole chewed through the back of the cabinet. Then bite marks along the edge of a door seal. Then a corner of a cereal box gnawed clean through. If rodents have gotten into your home, one thing is clear: they are not going to stop.

For a long time, the thinking was simple. Rodents gnaw to keep their teeth in check. Their front teeth never stop growing, so they grind them down on hard surfaces to stay healthy.

However, new research published in the journal Neuron adds something homeowners need to know. Scientists at the University of Michigan found that nerve signals from the teeth appear to trigger dopamine pathways in the brain. Rodents don't just gnaw because they have to. They gnaw because it feels good. And that changes how serious this problem really is.

The Science Behind the Chewing

Mice and rats have chisel-shaped front teeth called incisors that grow continuously throughout their lives. If they can't grind those teeth down, the teeth grow out of alignment and can interfere with eating. That's a survival issue.

What the new research shows is that the brain rewards gnawing with a dopamine release. When it happens, the brain signals that it feels good and keeps the behavior going. That means a rodent inside your home isn't going to stop chewing on its own. It will work through whatever is in front of it.

What Constant Gnawing Does to Your Home

Electrical Wiring: Rodents can gnaw through electrical wiring inside walls, putting your home at risk for fire. The damage is hidden and the consequences can be serious long after the rodent is gone.

Pipes and Plumbing: Norway rats can gnaw through plastic and lead pipes to reach food and water. A chewed pipe leads to slow leaks, water damage and mold that's expensive to fix.

Insulation and Structural Materials: Rodents tear through insulation to build nests and chew through drywall and wood framing. Structural damage can build up quietly with no obvious signs on the surface.

Food and Stored Goods: House mice nibble constantly, chewing through cardboard and thin plastic packaging to reach food. Rodents can contaminate food with bacteria like Salmonella, which causes serious illness.

Signs Rodents Are Already Gnawing in Your Home

Damage often starts before you ever see a single mouse or rat. Look out for these signs:

• Gnaw marks around doors, cabinets or food packaging. Fresh marks look rough. Older ones are smooth and may look greasy.
• Droppings near food sources or along walls. Mouse droppings are small and rod-shaped. Rat droppings are larger and capsule-shaped.
• Rub marks along walls left behind by oily fur.
• Nesting materials like shredded insulation or paper tucked into dark corners.
• Damaged food packaging with chewed holes or torn edges.
  One sign is enough reason to act. A single female house mouse can produce up to 35 young per year, so a small problem grows fast.

How to Keep Rodents Out

You can't stop a rodent from gnawing once it's inside. The only real fix is keeping them out and here’s the best way to start:

• Seal holes larger than a dime and gaps wider than a pencil with steel wool or silicone caulk. Mice fit through a dime-sized space. Rats fit through a quarter-sized hole.
• Install door sweeps on exterior doors and screen vents and chimney openings.
• Store food in airtight glass or metal containers instead of cardboard or thin plastic.
• Fix leaky pipes and keep attics, basements and crawl spaces dry.
• Keep firewood at least 20 feet from your home and trim shrubs back from the foundation.
• Reduce clutter in garages and storage areas where rodents like to hide and nest.

When to Call a Professional

If you're already seeing signs of activity, it's time to call in a professional pest control company. Rodents find new entry points fast and reproduce quickly. A licensed pest control professional can inspect your home, find where rodents are getting in and put together a plan that works.

Find a licensed pest control professional near you.