How to Keep Rats and Mice Out of Your Home (2026 Guide)

Orkin has ranked Los Angeles the most rat-infested city in the United States for multiple consecutive years through 2025. The combination of factors that create LA's extreme rodent pressure is unique:

Year-round breeding: Rats do not have a dormant season in LA's mild climate. In cold-climate cities, winter dramatically reduces rat reproduction. In LA, rats breed year-round, with females producing 4–6 litters of 6–12 pups annually — up to 72 offspring per female per year under optimal conditions.

Abundant food sources: LA's fruit trees (particularly citrus, avocados, and figs that drop fruit year-round), unsecured trash, compost bins, and outdoor pet food create an effectively unlimited food supply for urban rat populations.

Dense canopy and utility lines: Roof rats — the dominant species in LA — are excellent climbers. Mature trees, ivy ground cover, and utility lines that touch or overhang structures provide an extensive network of travel routes above the ground.

Aging infrastructure: Many LA homes built before 1970 have multiple unprotected entry points: gaps around pipes, damaged vent screens, open dryer vents, spaces under garage doors, and settling foundations with ground-level gaps.

The first step is finding how rodents are entering your home. Roof rats need a gap of only 1/2 inch (the size of a quarter) and mice need only 1/4 inch. Common entry points include:

• Roofline gaps: Where fascia boards meet, around roof vents, pipe penetrations through the roof, and under lifted roof tiles
• Utility penetrations: Gaps around plumbing pipes, gas lines, electrical conduit, and HVAC lines where they enter through walls or the foundation
• Attic vents: Damaged, corroded, or open-mesh screens over attic vents
• Garage doors: The space under a garage door (especially if the rubber seal is worn or the floor is uneven)
• Weep holes in stucco: Standard brick and stucco weep holes are 1 inch wide — more than large enough for a mouse and some rats
• Tree and vine contact: Branches or ivy within 3 feet of the roofline give roof rats access without entering at ground level
• Foundation gaps: Cracks in the foundation, gaps around crawl space vents, and open crawl space access points

To find active entry points, look for grease marks (dark smears from rat fur), droppings, gnaw marks, and disturbed insulation near the entry area.

Exclusion is the most important step in long-term rodent control. Without it, trapping becomes a revolving door — you remove existing rodents, but new ones enter through the same gaps.

Materials for exclusion:

• Hardware cloth (1/4 inch mesh): The most reliable material for closing openings. Bend and cut to fit irregular shapes. Use galvanized or stainless steel for longevity.
• Sheet metal: For larger gaps and structural openings. Rats cannot chew through metal.
• Steel wool plus caulk: For small gaps around pipes and wires. Rats can chew foam, wood, and plastic, but not steel wool. Always cover steel wool with caulk to hold it in place and prevent moisture-related rusting.
• Expandable foam: NOT recommended by itself — rats can chew through it. Only use foam if it will be covered with hardware cloth or sheet metal.

Specific fixes for LA homes:

• Replace damaged or open-mesh attic vent screens with 1/4-inch hardware cloth
• Install chimney caps and dryer vent covers
• Apply sheet metal flashing along the base of garage doors or install an appropriate door seal
• Cut tree branches to maintain 3-foot clearance from the roofline
• Trim ivy and other ground cover away from the foundation (ivy is a favorite rat nesting environment in LA)

After exclusion, trapping removes the existing rodent population inside the structure.

Snap traps are the most effective and recommended method for indoor rodent control. Place them:

• In the attic, along the walls where rodents travel
• In the garage, along walls and behind stored items
• In the crawl space, near signs of activity
• In cabinets under sinks, if activity is present inside the living space

Bait: Peanut butter, chocolate-peanut butter combinations, or nesting material (cotton balls, dried grass) are effective baits. Replace bait every few days if no catch is occurring.

Avoid rodenticide bait for indoor use. If a rat or mouse consumes rodenticide and dies inside a wall or in an inaccessible area, the decomposing body creates a severe odor problem. Additionally, rodenticide in an attic poses a risk of secondary poisoning to owls, hawks, foxes, and coyotes that eat poisoned rodents. LA has seen significant wildlife mortality from rodenticide secondary poisoning.

Check traps frequently. Check every 1–2 days. Remove dead rodents promptly using gloves and seal them in a plastic bag before disposal.

After resolving an active infestation, prevent recurrence:

Remove outdoor food sources:

• Pick up fallen fruit daily — citrus, avocado, and fig trees are major rodent attractants in LA
• Keep bird feeders away from the home or remove them entirely
• Store pet food in airtight metal or hard plastic containers; do not leave pet food outside overnight
• Secure trash cans with tight-fitting lids; use bins with locking mechanisms
• Keep compost in a rodent-proof bin

Reduce harborage:

• Remove ivy ground cover adjacent to the home — it provides ideal nesting habitat for roof rats
• Keep firewood stacked away from the home and elevated off the ground
• Clear clutter from garage and storage areas

Maintain exclusion:

• Inspect your home's exterior annually for new gaps (settling, pest damage, wood deterioration)
• Replace worn door sweeps and threshold seals
• Keep attic vent screens in good repair

Annual professional inspection: Have your exclusion work inspected annually, particularly for homes near canyons, storm drains, or with large tree canopy.

Call LA Pest Pros if: you hear scratching in walls or ceilings at night; you find rodent droppings in the attic or inside living spaces; you want a professional inspection to identify all entry points; or the problem has persisted despite DIY trapping. We cover 42 cities across Greater LA with professional rodent inspection, exclusion, and trapping services. Call (213) 691-0241 for a free estimate — 15-minute callback during business hours.

See: Rodent Control Services and Signs of Rats in Your Walls.

Call (213) 691-0241 for a free rodent inspection and exclusion estimate. LA Pest Pros serves 42 cities across Greater Los Angeles. Upfront pricing, same-day callbacks.