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Rats and Mice in the Attic: Signs, Risks and Removal

How to tell if rats or mice are living in your San Antonio attic, why they're a fire and health risk, and how professional rodent removal and exclusion work.

By Time's Up Pest Control. Published 2026-10-22.

Key Takeaways

  • Scratching at night, droppings, gnawed wires and greasy rub marks are the most common signs.
  • Rodents chew electrical wiring, contaminate insulation and can carry disease.
  • Mice fit through gaps about the size of a dime, and rats through gaps about the size of a quarter.
  • Lasting removal combines trapping with sealing every entry point.

If you hear scratching or scurrying above the ceiling at night, there's a good chance rodents have moved into your attic. In San Antonio, roof rats and house mice are the usual suspects, and fall is when most of them move in. Here's how to confirm it and what to do.

Signs of Rodents in the Attic

  • Noises at night: scratching, scurrying or gnawing in the ceiling or walls, usually after dark.
  • Droppings: mouse droppings are small, like a grain of rice. Rat droppings are larger, like a raisin, and often found along walls and near insulation.
  • Gnaw marks on wood, wiring, ductwork and stored boxes.
  • Grease or rub marks along beams and entry holes, where rodents' oily fur brushes the surface.
  • Tunnels and nests in insulation.
  • A strong, musky smell in the attic or near vents.
  • Pets staring at or pawing at walls and ceilings.

Why Rodents in the Attic Are a Real Risk

Fire hazard

Rodents' teeth never stop growing, so they gnaw constantly, including on electrical wiring. Exposed wires in a dry attic are a fire risk.

Health risk

Rodent droppings, urine and nesting material can carry bacteria and viruses. Disturbing contaminated insulation can put particles into the air, so don't sweep up droppings dry. Wear gloves, wet the area with a disinfectant first and wipe it up.

Property damage

Rodents tear up insulation, chew ductwork and stored belongings, and leave urine stains that soak into drywall.

How Rodents Get In

Mice can squeeze through a gap about the size of a dime, and rats through a gap about the size of a quarter. Common entry points include roof returns and soffits, gaps around plumbing vents, gable vents with damaged screens, AC line openings and tree branches that hang over the roof.

How Professional Rodent Removal Works

  1. Inspection of the attic, roofline and foundation to find activity and every entry point.
  2. Trapping and removal to clear the rodents already inside.
  3. Exclusion, which means sealing entry points with durable materials rodents can't chew through.
  4. Monitoring to make sure no new activity appears.

Trapping without exclusion is a temporary fix. As long as the openings stay, new rodents will move in.

What Not to Do

  • Don't rely on poison bait inside the attic. Rodents can die in walls and cause odor problems.
  • Don't seal entry holes before the rodents inside are removed. Trapped rodents may chew new holes into the living space.

How Time's Up Pest Control Can Help

Time's Up Pest Control provides rodent inspections, removal and exclusion for San Antonio homes and businesses. Our licensed technicians find how they're getting in and help close it off. Learn about our prevention programs, or read our winter pest-proofing guide.

Frequently Asked Questions

How do I know if it's rats or mice in my attic?

Droppings are the best clue. Mouse droppings are about the size of a grain of rice, and rat droppings are closer to the size of a raisin.

When do rodents move into attics in San Antonio?

Most move in during fall as temperatures drop, but rodents can get into attics any time of year.

Can rodents in the attic cause a fire?

Yes. Rodents gnaw on electrical wiring, and damaged wires can overheat or spark.

Contact Time's Up Pest Control

Time's Up Pest Control is a family-owned San Antonio pest control company serving homes and businesses. Licensed technicians (TPCL #877175), free estimates, satisfaction guarantee and 24/7 emergency service.

Phone: (210) 868-2267

Email: info@timesupbugs.com

Address: 1800 NE Interstate 410 Loop, Suite 216-B, San Antonio, TX 78209

Services: Pest Control, Termite Control, Pest Prevention, Commercial Pest Control