Rodent Control in Los Angeles for Roof Rats, Norway Rats and Mice

Most Los Angeles rodent calls involve one of three animals, and they are not interchangeable. UC IPM describes roof rats as present in almost every California city, partial to warm and coastal climates, and with a documented range that is still expanding.

Roof rats nest high, in attics, ceiling voids, trees and dense ivy, and they eat the fruit Southern California yards are full of, often feeding on citrus and avocados before it falls. Norway rats work the ground floor instead, digging along foundations and under woodpiles, sheds and trash areas. House mice live almost entirely indoors and stay close to one nest.

Older housing raises the odds that any of the three gets inside. County planning documents for unincorporated San Gabriel Valley communities give a sense of the age involved: in the combined East Pasadena–East San Gabriel planning area, 83.6% of the 9,517 housing units were built before 1979, and in South San Gabriel about two-thirds of homes predate 1979.

Decades of weather loosen foundation vent screens, eave boards and door thresholds, which is why PesPro's own service notes for the San Gabriel Valley flag older housing stock and the Rio Hondo and San Gabriel River corridors as steady sources of rodent pressure.

Many residents assume the local mosquito district will come out for rats. It will not. The San Gabriel Valley Mosquito & Vector Control District states that it does not handle rodents, and the Greater Los Angeles County Vector Control District refers rodent questions to the county's Vector Management Program, whose published guidance focuses on sanitation, rodent-proofing and safe cleanup. Turning that guidance into traps on the right beams and a schedule of follow-up visits is the work a private rodent control program does. [1] [7] [8] [9] [10]

The rodent-linked illness Los Angeles County watches most closely right now is flea-borne typhus. The Department of Public Health reported 220 cases in 2025, the most it has ever recorded, up from 187 in 2024, and nearly nine in ten patients identified were hospitalized. Outbreaks that year were investigated in central Los Angeles, Santa Monica and unincorporated Willowbrook. By September 22, 2026 the county had counted 109 more cases, including an outbreak in Wilshire Center, and described the risk as county-wide. The infected fleas are commonly found on rats, free-roaming cats and opossums, and the animals usually look healthy.

That flea link changes how a rodent job should be done. The county's Vector Management Program points out that fleas leave a dead rodent to look for a new host, so fleas should be controlled before or alongside trapping and baiting where typhus is a concern. The same county advisory lists plague, murine typhus, hantaviruses and arenaviruses among the pathogens its rodent surveillance has turned up, spread by flea bites or by contact with urine, droppings and nesting material.

Each species carries its own risks. UC IPM links rats to leptospirosis, salmonella and other foodborne bacteria, and rat-bite fever, and notes that roof rats nesting in attics can cause electrical sparks and fires by gnawing wiring. House mice can carry lymphocytic choriomeningitis (LCM), and their urine is a major allergen associated with childhood asthma. The hantavirus behind most U.S. cases of hantavirus pulmonary syndrome is spread mainly by the deer mouse, according to the CDC, which is a reason to handle any rodent droppings carefully rather than a reason to panic over a house mouse in the kitchen. [3] [4] [5] [1] [2] [6]

Rats are suspicious of anything new in their path. UC IPM calls this neophobia, notes that it is stronger in roof rats, and says rats may avoid a new trap or bait for several days or even weeks. Roof rats may not enter a bait station at all, even one placed on their runway. A homeowner who sets out poison and sees the bait untouched for a week often concludes it is not working and gives up just as the rats were getting used to it.

When bait does work indoors, it creates a different problem. The county's rodent advisory recommends snap traps inside buildings in most cases, because a poisoned rodent can crawl into a wall or ceiling void and die where no one can reach it, leaving odor and flies.

Anticoagulant baits also build up in the animal, so UC IPM warns that a single poisoned rat can carry several lethal doses for the dog, cat, owl, hawk or coyote that eats it. Outdoors, the county says baiting should come only after the building itself is rodent-proofed, so poisoned rats do not move inside to die.

Trapping that works is specific to the species. For Norway rats and mice, UC IPM recommends snap traps set against walls with the trigger toward the wall, mouse traps no more than about 10 feet apart, and rat traps about 10 to 20 feet apart, with a dozen or more for a heavy rat infestation.

Roof rat traps belong off the ground on beams, ledges, pipes, fences and branches, fastened in place. Pre-baiting traps without setting them, until the bait disappears several times, helps get past the rats' caution. A store-bought trap on the kitchen floor can sit untouched for weeks under a roof rat that never comes down from the attic. [1] [2] [5]

Traps reduce the rodents already on a property; what the yard offers decides how quickly new ones move in. The county's Vector Management Program asks residents not to leave pet food out at night and to pick up fallen fruit promptly, and UC IPM adds that pets should only be given what they finish in one sitting, with the rest kept in rodent-proof containers. In neighborhoods with backyard oranges, lemons and avocados, ripe fruit left hanging or lying under the tree is a nightly meal for roof rats that may travel hundreds of feet to reach it.

Cover matters as much as food. UC IPM singles out Algerian and English ivy on fences and hedges as roof rat habitat, recommends keeping shrubs apart from each other and away from walls, and advises cutting back tree limbs that touch or overhang the roof so rats cannot use them as bridges.

The county recommends thinning vegetation and either removing stored items or raising them about 18 inches off the ground, which takes away the dark, protected spots under lumber, boxes and old furniture where Norway rats and mice nest. Its typhus guidance repeats the same steps: tight trash lids, trimmed brush, no outdoor pet food, and sealed crawl spaces.

Rodents also look for shelter in places people do not think of as part of the house. UC IPM notes that rats commonly gnaw the insulation on engine wiring in cars and trucks, and suggests a weighted car cover that reaches the ground for vehicles parked outdoors for long periods. Inside, both the county and UC IPM set the same benchmark for the building itself: openings larger than 1/4 inch should be closed with metal hardware cloth, sheet metal or concrete. Foam, plastic, rubber and wood do not hold up, and lightweight chicken wire is not recommended. [5] [1] [2] [3]

PesPro sells rodent work as two separate services, and it helps to know which one you are asking for. Rodent Control, this page, is the ongoing subscription: an inspection of the attic, crawl space, garage and yard to find which species is active, traps and bait stations placed to match it, and scheduled monitoring and maintenance visits that keep the program working. Rodent Exclusion is the structural add-on that physically seals vents, gaps, utility penetrations and foundation cracks; it can be packaged with a control program or ordered on its own for a building that needs whole-structure sealing.

The split exists because the jobs are different. A control program deals with the rats and mice already living on the property and the conditions drawing more in; exclusion keeps new ones from getting back into the structure. A home with roof rats in a fruit tree and ivy along the back fence may need both, while a house mouse problem in a well-sealed condo may only need trapping and monitoring. Sanitization and insulation work for attics and crawl spaces left soiled by rodents can also be packaged with the program, and trapped rodents are removed during service visits.

Cleanup is the step most people get wrong. The county advises against disturbing droppings and nesting material, for example by sweeping them up dry, because that can put contaminated particles in the air. Its guidance is to wear rubber, latex, vinyl or nitrile gloves, air out closed spaces first, soak droppings, nests and trapped rodents with a household disinfectant, then wipe them up and double-bag them for the trash.

Commercial kitchens follow a different track: rodent programs for restaurants run under PesPro's restaurant service with inspection-ready service logs. For homes and other properties, rodent control is quoted after an inspection, since property size, rodent activity and visit frequency set the scope. [5]