Rats move in for food, water, and shelter, and a Los Angeles yard often supplies all three at once: fallen citrus, pet food left out overnight, a dripping irrigation valve, and a fence covered in ivy. Inside, the early evidence is droppings, dark rub marks along baseboards, gnaw marks on wood and wiring, and scratching inside walls after dark. This guide covers what attracts rats to San Gabriel Valley homes, the signs they are already inside, and what actually gets them out.
What attracts rats to a house in Los Angeles?
Unsecured food, and in this region that usually means fruit. UC IPM notes that roof rats eat oranges, avocados, and other fruit directly on the tree, and that they travel 300 feet or more for food, so the attractant can even be a neighbor's unpicked tree. Backyard citrus, avocado, and loquat trees across the San Gabriel Valley carry fruit for much of the year, and whatever drops stays edible for days.
The rest of the food list is household routine:
- Fallen and overripe fruit. Harvest ripe fruit promptly and rake up drops, including fruit rotting under the canopy.
- Pet food outdoors. A bowl left on the patio feeds rats after dark. Bring food and water bowls in every evening.
- Bird feeders. Spilled seed under a feeder is restocked daily. Use a tray that catches spills, or take the feeder down while there is rat activity.
- Accessible garbage. Cans without tight-fitting lids, overfilled bins, and bags set beside the can. UC IPM says to keep garbage in rodent-proof containers with tight lids.
Water matters just as much in a dry climate. Dripping irrigation valves and hose bibs, fountains, birdbaths, pet water bowls, and a neglected pool or spa all give rats a reliable drink. Fix the leaks and empty what you can.
Which plants and clutter give rats shelter?
Dense vegetation above ground, and clutter at ground level. UC IPM describes roof rats nesting off the ground in trees, shrubs, and thick ground cover such as ivy, so an ivy-covered fence or slope is ready-made harborage. Untrimmed palms with a skirt of dead fronds shelter roof rats the same way. Any limb within 6 feet of the roofline is also a bridge; UC IPM says to remove overhanging branches and to thin or remove climbing ivy.
Norway rats shelter low. They burrow along foundations and under woodpiles, rubbish, and stored junk, so firewood stacked against the house and clutter sitting on the ground beside a wall invite them. Store firewood and other items at least 18 inches off the ground and away from walls, or remove them. Near the Rio Hondo and San Gabriel River corridors around our El Monte office, this pressure never fully stops, which is why prevention has to be ongoing.
What are the signs of rats in your house?
Droppings come first, and length tells you a lot. Rat droppings run about 1/2 inch for roof rats and 3/4 inch or longer for Norway rats, while mouse droppings measure 1/4 inch or less. Fresh droppings are dark, moist, and soft; old ones turn gray and crumble. Check along ground-floor walls, under sinks, inside cabinets, and in attic insulation. Handle them with gloves and never dry-sweep them; the FAQ below covers safe cleanup.
The other indoor signs:
- Rub marks. Dark, greasy smudges along baseboards, pipes, and rafters, left by fur on a runway in regular use.
- Gnaw marks. Fresh, pale chew marks on wood, plastic, and stored boxes. Gnawed electrical wiring is a fire hazard and a reason to act quickly.
- Odor. A persistent musky smell in a closed room, or a stronger dead-animal smell from a wall or ceiling void.
- Pet behavior. A dog or cat that stares at or paws one wall, cabinet, or appliance is often reacting to movement you cannot hear.
Which species left the evidence changes where traps go and what gets sealed. Our guide to roof rats vs. Norway rats compares droppings, nesting height, and trap placement for both species and the house mouse.
What do nighttime noises in the walls mean?
Rats are active mostly at night, so scratching, gnawing, and running sounds that begin after dark and stop by morning point to rodents. Rats in walls use the vertical voids as highways between floors, which is why the same animal can be heard at baseboard height and then overhead minutes later. Roof rats favor attics and ceiling voids, where they sound like quick footsteps in the evening; Norway rats keep to crawl spaces and ground floors.
Daytime noise is more likely squirrels or birds, which need a different plan. Noise inside the walls means rodents are living in the structure, not just visiting, so pair any trapping with a search for entry points.
What are the signs of rats outside?
Each species leaves its own evidence at its own height. Norway rats dig: look for freshly disturbed soil and burrow openings at the base of the foundation, under woodpiles, and along garden walls and sidewalks. Burrows with clean, packed entrances are in use.
Roof rats leave their evidence higher. Watch for fruit hollowed out to the rind while still on the tree, droppings along fence tops and garage rafters, and smudge marks where they cross pipes and beams. Branches touching the roof, heavy ivy, and utility lines are their routes. Chewed vent screens at the roofline and gnawed corners at the eaves are signs a route now ends inside your attic.
Is it rats, or a mouse infestation?
The signs scale down. Mouse droppings measure 1/4 inch or less, gnaw marks show much finer tooth grooves, and the sounds are closer to light scratching than running. Mice also stay close to the nest, so their evidence concentrates in one cabinet, one drawer, or one corner of the garage, while rats range across the whole structure. The distinction matters: mice need even smaller gaps sealed and much tighter trap spacing. The species guide linked above settles most cases from the droppings alone.
What actually gets rid of rats?
The honest answer to how to get rid of rats is three jobs, in order: remove the attractants, seal the openings, and trap the animals already inside. Sanitation strips the yard of the food, water, and shelter listed above. Exclusion seals every opening larger than 1/4 inch with metal, because UC IPM warns that rats chew through plastic, foam, wood, and caulk. Trapping then removes the rats that remain, placed on the routes the droppings and rub marks reveal.
Poison alone does not solve a rat problem. California prohibits most uses of anticoagulant rodenticides, LA County Public Health prefers snap traps indoors because a poisoned rat can die inside a wall void, and bait does nothing about the openings, so new rats replace the old ones. UC IPM adds that without ongoing sanitation, the benefits of every other measure are lost.
Call a professional when activity shows up on more than one level, when droppings reappear after you trap, or when you find gnawed wiring. PesPro's Rodent Control program combines trapping, monitoring, and prevention, the inspection and written quote are free, and rodents are covered by the first tier of our 30-day guarantee: if the problem reappears within 30 days, the third visit is on us.
Frequently asked questions
Will cleaning up the yard alone drive the rats out?
Not once they are nesting indoors. Removing food and water makes traps work better, because hungry rats approach bait sooner, but an established colony in the walls or attic still needs trapping and sealed entry points. The reverse also fails: UC IPM warns that without ongoing sanitation, rats return quickly after control work. Do both, and keep the sanitation permanent.
Is it safe to clean up rat droppings myself?
Small amounts, yes, with precautions. Wear gloves, wet the droppings with a household disinfectant, and wipe them up. The CDC warns never to sweep or vacuum dry droppings, because that puts virus-carrying particles into the air. LA County's Vector Management Program has found local rodents carrying hantaviruses and the bacteria that cause murine typhus and plague. Leave large accumulations, such as a contaminated attic, to a professional crew.
Who does the work, and what does it cost?
The inspection and written quote are free. PesPro is a QualityPro-accredited company operating under California license PR-6378 from its El Monte headquarters, with a bilingual team covering Los Angeles and San Bernardino counties. Pricing depends on property size, activity level, and service frequency, and same-day service is available for an extra fee depending on the day's route. Call the 24/7 line at (323) 472-5329 or start on the contact page.
Sources
- UC IPM Pest Notes: Rats
- UC IPM Pest Notes: House Mouse
- LA County Public Health: Rodent-Borne Diseases, Risk Reduction Recommendations (PDF) (publichealth.lacounty.gov)
- CDC: How to Clean Up After Rodents (cdc.gov)