Mice and Rats in San Antonio Homes: Signs, Risks and Control
Three rodents cause most indoor problems in Texas: the house mouse, the roof rat and the Norway rat. The lasting fix is to seal the gaps they use, remove the food and shelter that hold them, and trap the ones already inside. Bait and traps without sealing only make room for the next arrivals. Don't sweep or vacuum droppings, because the dust can carry disease.
To get an inspection and a sealing plan, call or text (210) 281-1064 or book online.
Is it a mouse or a rat? #
Texas A&M AgriLife lists the house mouse, roof rat and Norway rat as the three species of concern. Weights below come from UC IPM; dropping sizes come from Texas A&M and Cornell.
| House mouse | Roof rat | Norway rat | |
|---|---|---|---|
| Weight | About 1/2 oz | 5–10 oz | 7–18 oz |
| Build | Small, big ears, nearly hairless tail | Slim, pointed nose, tail longer than head and body | Heavy, blunt nose, tail shorter than head and body |
| Droppings | 1/8–1/4 in, pointed ends | About 1/2 in | 3/4–1 in |
| Where it lives | Near food, inside walls, cabinets, boxes | Up high: attics, rafters, trees, vines | Down low: burrows by foundations, woodpiles, sewers |
A house mouse is 5 to 7 inches long counting its 3- to 4-inch tail. Deer mice, which matter because of hantavirus, have a tail covered in fur. Texas Tech's Mammals of Texas calls the roof rat common across most of the state, especially in towns, and describes the Norway rat as widespread.
How do mice and rats get in? #
Texas A&M says a mouse can squeeze through a dime-size opening or a 1/4-inch crack beneath a door, and a rat through a quarter-size opening or a 1/2-inch crack.
- Roof rats climb. They run along utility lines, fence tops, tree limbs and vines to reach roofs, then slip into attics through vents, eaves and gaps around pipes.
- Norway rats dig. They tunnel along foundations and under slabs, sidewalks and woodpiles, and they follow sewers, ditches and creeks to new territory. They are strong swimmers.
- House mice come in through low cracks, pipe gaps and door gaps and nest close to food.
How far they roam shapes where to look. Texas A&M puts a house mouse's range at about 30 feet from the nest, a Norway rat's at about 150 feet and a roof rat's at up to 300 feet.
When are rodents worst? #
Texas A&M says infestations can happen at any time of year but show up most often in fall and winter. Mice don't hibernate, and many that spent summer outdoors move in. Breeding is fast:
- A house mouse may raise 5 to 10 litters a year of 5 or 6 young, which are ready to breed within 5 to 6 weeks.
- Roof rats breed all year in Texas, with peaks in February to March and May to June, according to Texas Tech.
- Norway rats have 4 to 6 litters a year, with peaks in spring and fall.
AgriLife's rodent IPM guide says to act on the first sign of a single mouse.
What are the signs of rodents? #
Rodents are busiest in the two hours after dusk and reuse the same routes along walls. Look and listen for:
- Droppings shaped like dark grains of rice, as DSHS describes them, near food, under sinks and along walls
- Gnaw marks on wood, plastic, wiring and food packages
- Dark, greasy rub marks along beams, pipes and baseboards
- Nests of shredded paper, fabric or insulation in walls, boxes and drawers
- A musky smell in long-running mouse problems
- Scratching in walls or ceilings at night
- Smooth-edged burrow holes along the foundation
Noise in the attic during the day usually points to squirrels, not rats. Our wildlife guide covers squirrels, raccoons and opossums.
Are mice and rats dangerous? #
Mostly through what they leave behind. The CDC says rodents spread disease when people handle them, touch their droppings, urine or saliva, are bitten, or breathe dust or eat food contaminated by them.
- Hantavirus. In the U.S. it spreads mainly from the deer mouse. Symptoms appear 1 to 8 weeks after exposure. DSHS says reported cases in Texas are rare.
- LCM virus. The house mouse is the main host; a 2016 CDC report estimated about 5% of U.S. house mice carry it.
- Other infections include leptospirosis, rat-bite fever and salmonella food poisoning.
- Flea-borne typhus. The Texas Department of State Health Services names rats and their fleas as the natural reservoir and lists Bexar County among the newer areas where typhus is established. DSHS advises treating for fleas before starting rodent control, so the fleas don't move from dying rats to people. See our flea guide.
- Fire. UC IPM links rodents gnawing on wiring to many fires whose cause is never found.
Mice and rats are not a rabies concern; DSHS rates rodents as low-risk animals. See a doctor about any fever after contact with rodents, and mention the contact.
How do you clean up droppings safely? #
The CDC's cleanup steps are designed to keep virus-laden dust out of the air:
- Open doors and windows and leave the area for 30 minutes.
- Put on rubber or plastic gloves. Don't sweep or vacuum.
- Spray droppings, urine and nests until soaked with a fresh mix of 1 1/2 cups of bleach in a gallon of water, or a registered disinfectant, and let it sit 5 minutes.
- Wipe up with paper towels and throw them in a covered trash can.
- Double-bag dead rodents and nests, then wash gloved hands and bare hands.
DSHS notes that heavy infestations may call for respiratory protection, which is a good time to bring in a professional.
What actually keeps rodents out? #
AgriLife calls rat-proofing the most permanent form of control. Steps that help:
- Seal any opening larger than 1/4 inch. CDC suggests steel wool packed with caulk or foam for small holes, and hardware cloth, sheet metal or cement for larger ones. Rats can gnaw through caulk, foam, plastic and wood, and chicken wire is too flimsy.
- Add door sweeps and cover vents with 1/4-inch hardware cloth.
- Cut back tree limbs to at least 6 feet from the roof and thin vines on walls.
- Store food in sealed containers, use lidded trash cans and don't leave pet food out overnight.
- Keep firewood and lumber on racks off the ground and clear clutter.
- For businesses, keep dumpsters clean, lidded and away from doors; Texas A&M ties Norway rats to poor dumpster sanitation.
Skip ultrasonic, magnetic and vibration gadgets; UC IPM found little evidence they drive out established mice.
How do professionals remove rodents? #
Texas A&M's approach combines inspection, sanitation, rodent-proofing, traps and baits. Snap traps are the CDC's choice. For mice, traps go along walls no more than about 10 feet apart; for roof rats, off the ground. Rats avoid new objects, so traps are often baited but left unset until the bait has been taken several times. CDC advises homeowners against glue boards and live traps, which frighten rodents into urinating and raise the risk of illness.
Rodenticides are tightly regulated. The EPA requires professional products to go in tamper-resistant bait stations anywhere children under 6, pets or wildlife could reach them and at all outdoor above-ground spots. Texas A&M says baits belong only where rodents are confirmed, not on a calendar. Poisoned mice often die inside walls, which is one reason trapping is preferred indoors.
Will the city handle it? #
No. The City of San Antonio's Metro Health vector control program says it doesn't treat private property for insect or rodent problems. Rodents on private property are up to the owner.
How does Pest Trappers handle rodents? #
We handle mice and rats in homes and businesses across San Antonio, Stone Oak, Schertz, New Braunfels and Kerrville.
- Inspection. The technician checks from the roofline to the foundation for entry points, droppings, rub marks and nests, and identifies which rodent you have.
- Options. You'll hear the options, which can include sealing, trapping and baiting, plus the sanitation steps that make them work. If fleas are present, DSHS advises dealing with them first, and the technician will explain how.
- Label and EPA rules. Every product is used as its label requires. The work is done under Pest Trappers LLC (TPCL #0887549), a family-owned San Antonio company.
- Follow-up. Return visits are planned as needed until activity stops.
Pricing is quoted after the inspection. Book online or call or text (210) 281-1064, and the office will confirm your time. Se habla español. More on our rodent control page.