When the first real cold front drops down over Austin in late fall, the mice, cockroaches, and scorpions that spent summer in your yard start hunting for a warmer, wetter place to wait out the season, and a heated house with a few unsealed gaps is the easiest target on the street. Most of them get in through openings you walk past every day without noticing.

Quick answer: You winterize an Austin home against pests by closing the gaps they use to get inside before that first front arrives. Mice need only a quarter-inch opening, so the work comes down to sealing utility and pipe penetrations, adding door sweeps and weatherstripping, screening vents and weep holes, and clearing firewood and vegetation off the walls.

A mouse can squeeze through a hole about a quarter inch across, roughly the width of a pencil, according to the CDC's rodent guidance [1]. That single number is why exclusion works: seal the openings and you shut out most of what tries to move in. This checklist walks through where to look and what to do, in the order that makes sense for a weekend of work.

Why pests move toward your house as Austin cools down

Pests come inside in fall for three plain reasons: warmth, water, and a dark place to shelter. Austin winters are mild, but mild is not the same as pest-free. The January average high sits near 63 degrees and the average low near 42 degrees, based on 1991 to 2020 climate normals compiled from National Centers for Environmental Information data [6]. Those overnight lows are cold enough, and the air dry enough, to push insects and rodents toward the steady heat and moisture your home gives off.

The striped bark scorpion is the most common scorpion in Central Texas, a yellowish-tan arachnid that reaches about two and a half inches long. Texas A&M AgriLife entomologists note that when conditions outside turn harsh, scorpions seek a more hospitable environment and a source of water, which often means the inside of a wall or a cool bathroom [3]. American cockroaches follow a different path in. They live in sewers and drains, then move up through drainage pipes into kitchens and bathrooms and settle near furnaces and heating ducts, where it stays warm, as the Texas A&M urban entomology program describes [4].

Rodents want the same things and travel light. Spiders show up because the insects do, hunting the flies and roaches that gathered near your foundation. Add the occasional invaders that wander in when the weather turns, and you have a steady trickle of unwanted guests, all using the same handful of entry points. Close those points and you cut off most of the traffic at once.

Start with a walk-around before you seal anything

Give yourself twenty minutes and circle the house slowly, because you cannot seal a gap you have not found. Carry a flashlight and a notepad, and check inside and out at the spots pests use most.

• Where pipes, gas lines, air-conditioning lineset, cable, and electrical conduit pass through exterior walls. These utility penetrations are rarely sealed well, and the gap around them is a common rodent doorway.
• The bottom of every exterior door. At dusk, turn on an inside light and look from outside: any daylight or lamplight showing under or beside the door is a gap a mouse or scorpion can use.
• Weep holes in brick or stone veneer, the small vertical slots near the base of the wall that let the wall breathe.
• Foundation vents, dryer vents, attic and soffit vents, and any torn window screens.
• The garage, especially the corners of the garage door where the seal has worn away, plus the door from the garage into the house.

Write down what you find. The list you build here becomes the checklist you work through next.

Your winter pest exclusion checklist

Work through these in order. The early steps close the biggest doorways, so even if you stop halfway you will have shut out most of what tries to get in.

1. Seal gaps and utility penetrations

1. Fill small holes and cracks with steel wool packed tight, then run a bead of caulk around it to hold it in place. The CDC recommends this exact combination because rodents chew through soft filler alone but not through the metal fibers [1].
2. For larger openings around pipes, use a rigid material the CDC lists for the job: hardware cloth, sheet metal, cement, or metal lath cut to fit the gap [1].
3. Seal cracks, crevices, and pipe penetrations in exterior walls with a quality exterior sealant, the same step AgriLife recommends for keeping scorpions out [3].

2. Fit door sweeps and weatherstripping

A mouse can slip under a quarter-inch gap beneath a door, and a rat needs only about half an inch, per Texas A&M AgriLife's rodent management guidance [2]. The gap under a typical exterior door is often wider than that.

• Install a door sweep on every exterior door, including the door from the garage to the house, so the sweep touches the threshold with no daylight showing.
• Replace worn weatherstripping around doors and windows, which AgriLife names as a specific step for excluding scorpions [3].
• Repair or replace torn window screens and make sure each screen fits tightly in its frame [3].

3. Screen vents and weep holes

Vents and weep holes have to stay open to do their job, so you cover them rather than plug them. Because a mouse passes through anything wider than a quarter inch [1], use hardware cloth with openings no larger than a quarter inch.

• Cover foundation, attic, soffit, and dryer vents with quarter-inch hardware cloth, cut slightly oversized and fastened flat so pests cannot push behind it.
• Fill weep holes with steel wool, copper mesh, or screen wire, the materials AgriLife lists, or fit purpose-made weep-hole covers that block pests while letting the wall drain [3].

4. Clear the yard, firewood, and clutter

The strip of ground right against your walls decides how much pressure your seals face. A woodpile or a shrub touching the siding is a bridge and a hiding spot rolled into one.

• Move firewood well away from the house and up off the ground, since stacked wood against the wall gives scorpions and rodents cover right at the entry points [3].
• Trim tree limbs, shrubs, and other vegetation so nothing touches the structure, and keep the grass near the foundation short [3].
• Clear leaf litter, mulch pileups, and yard debris away from the foundation, since that damp cover is exactly what scorpions and roaches shelter under [3][4].

5. Cut off water and food inside

Sealing keeps most pests out, and taking away what draws them makes the ones that do get in leave. American cockroaches in particular hunt for moisture [4].

• Fix dripping faucets and leaking traps under sinks, and wipe down damp spots in bathrooms and the laundry area.
• Store dry pantry goods and pet food in sealed containers, and keep counters and the area around the trash can clean.
• Run a dehumidifier in a damp garage or utility room to make the space less appealing to roaches and the spiders that follow them.

Where Natran fits

Many Austin homeowners start searching for eco-friendly or green pest control right when they begin a project like this. What people usually mean by those terms is prevention first: keeping pests out by design instead of spraying on a fixed schedule. That is the framework Natran Green Pest Control works from, a form of Integrated Pest Management that the US EPA describes as inspecting, identifying the pest, using prevention as the foundation, and treating only when monitoring shows it is warranted, with broad spraying kept as a last resort [5].

In practice, that means a technician inspects your home and finds the entry points you might miss, identifies which pests you actually have, and focuses on exclusion and targeted treatment rather than a routine spray of the whole property. The benefit is that you solve the cause instead of the symptom, and the outcome is a house that stays quieter through winter because the pests never get a foothold. The checklist above is the same prevention-first logic you can start on yourself this weekend.

The takeaway

Winter pest problems in Austin are mostly a sealing problem. The mice, roaches, scorpions, and spiders that want your warmth all come in through gaps around pipes, under doors, and through open vents and weep holes, and a mouse needs only a quarter-inch opening to do it. Walk the house, write down every gap, and work down the checklist starting with the biggest openings. Do that before the first cold front, keep firewood and vegetation off the walls, and you handle most of the season before it starts.

Frequently asked questions

When should I winterize my Austin home against pests?

Do it in fall, before the first strong cold front pushes through, usually October or November in the Austin area. That is when overnight lows near 42 degrees start driving pests toward shelter [6]. Sealing early means the gaps are closed before rodents and scorpions begin looking for a way in, rather than after you already have them inside a wall.

What size gap can let mice or roaches into my house?

A mouse can fit through an opening about a quarter inch wide, roughly the width of a pencil, and a rat needs only about half an inch, according to the CDC and Texas A&M AgriLife [1][2]. Cockroaches use even smaller cracks, along with drains and pipe openings [4]. Because these gaps are so small, careful sealing and quarter-inch hardware cloth do most of the work.

What is the best material to seal holes against rodents?

For small holes, the CDC recommends packing steel wool tight and caulking around it, because rodents chew through soft filler but not metal fibers [1]. For larger gaps, use hardware cloth, sheet metal, cement, or metal lath [1]. For weep holes that must stay open, AgriLife suggests steel wool, copper mesh, or screen wire so the wall can still drain [3].

Do I really need to worry about pests in Austin's mild winter?

Yes. Mild does not mean warm. Austin's January nights average around 42 degrees [6], cold enough to send scorpions and rodents indoors toward heat and water [3]. American cockroaches move up from sewers and settle near warm heating ducts year round [4]. A mild winter actually keeps more pests active locally, so exclusion matters as much here as it does in colder states.

Can I do pest exclusion myself, or should I call a professional?

Most of this checklist is genuine do-it-yourself work: caulk, door sweeps, hardware cloth, and yard cleanup take a weekend and basic tools. Call a professional when you find droppings or hear activity in the walls, when the entry points are hard to reach, or when you want a trained inspection to catch the gaps you missed. A prevention-first company can handle exclusion and targeted treatment together.

Reference Sources

1. Centers for Disease Control and Prevention. "How to Seal Up to Prevent Rodents." US CDC. https://www.cdc.gov/healthy-pets/rodent-control/seal-up.html
2. Texas A&M AgriLife Extension, Entomology. "Rodent IPM." https://extensionentomology.tamu.edu/wp-content/uploads/sites/8/2022/05/Rodent-IPM.pdf
3. Texas A&M AgriLife Today. "Hot, dry summer has scorpions in South Central Texas heading indoors," 2018. https://agrilifetoday.tamu.edu/2018/06/30/hot-dry-summer-has-scorpions-in-south-central-texas-heading-indoors/
4. Texas A&M University, Urban and Structural Entomology Program. "American Cockroach, Periplaneta americana." https://urbanentomology.tamu.edu/cockroaches/american/
5. US Environmental Protection Agency. "Integrated Pest Management (IPM) Principles." https://www.epa.gov/safepestcontrol/integrated-pest-management-ipm-principles
6. Current Results, reporting National Centers for Environmental Information 1991 to 2020 climate normals. "Austin TX Weather in January." https://www.currentresults.com/Weather/Texas/Places/austin-weather-in-january.php