Roof Rats

While Roof Rats are not native to Arizona, households in the Greater Phoenix area have reportedly seen an increase of this rodent species in the past few years.

If you have Roof Rats, or have seen Roof Rats in your neighborhood, call the Maricopa County Environmental Complaint line at 602.506.6616 or log your complaint at www.maricopa.gov/envsvc. Vector Control officers can identify and test rat specimens to determine if you have Roof Rats.

Frequently Asked Questions

roof-rat-pest-id-card_frontWhat is a Roof Rat

Roof Rats (Rattus rattus), sometimes called black rats, fruit rats or house rats, are aerial, very agile climbers and usually live and nest above ground in shrubs, trees, and dense vegetation such as ivy.

Roof Rats are long and thin rodents that have large eyes and ears, a pointed nose and a scaly tail. Roof Rats have soft and smooth fur that is typically brown with intermixed spots of black. Their undersides are often white, gray or black.

Adult Roof Rats measure 6-8” (16-20 cm) when combining their head and body length. Their tails are notably longer than their heads and bodies, measuring 7-10” (19-25 cm). This means that Roof Rats can measure more than 40 cm long. They usually weigh 5-9 ounces (150-250 g), but can grow up to 12 ounces (340 g).

Roof Rats travel from trees to roofs or from accesses near overhead utility lines, which they use to travel from area to area. In buildings, they are most often found in enclosed or elevated spaces in attics, walls, false ceilings, and cabinets. They have been found in swimming pools, laundry rooms, attics, garages and patios, as well as on power lines.

Roof Rats spend 90 percent of their life four feet or more off the ground. Although very rare, Roof Rats can enter a home’s plumbing system, most likely from the vent stack that protrudes from your roof.

What are common signs of Roof Rat activity?

  • Hollowed citrus and other fruit
  • Noises in the attic and walls (especially at night)
  • Gnawing sounds and gnaw marks around roof eaves
  • Damage to plastics and covering on electrical wires

How do Roof Rats get into a house?

  • Roof Rats frequently enter homes and garden sheds through any opening larger than a nickel
  • They follow pipes down from the attic, sneak through doggie doors, gnaw through drywall and enter kitchens, bathrooms or base sink cabinets
  • They chew through wood, plastic, aluminum siding, and dry wall
  • These rodents are fond of attics because they provide a safe refuge and a nesting place for their young
  • Roof Rats have been known to enter the sewer system through the roof vent pipes

What can I do to keep Roof Rats out of my house?

  • Contact an exterminator for assistance
  • Keep fruit from trees away from your roof remembering that rats can jump from trees to your roof
  • Use stucco diamond mesh to screen and seal all holes and vents leading to your home
  • Look for holes in exterior walls and near hot water heaters, washers and dryers (dryer vent pipes) and sewer stacks on the roof.
  • Caulk all cracks
  • When rodent-proofing against Roof Rats, pay close attention to the roof and roof line areas to assure all accesses are closed
  • Plug or seal all openings of greater than 1/2 inch (1.3 cm) diameter with concrete mortar, steel wool, or metal flashing
  • Rodent-proofing against Roof Rats usually requires more time to find entry points because of their greater climbing ability
  • Eliminate vines growing on buildings and, when feasible, overhanging tree limbs that may be used as travel routes
  • The elimination of food and water through good sanitation practices can do much to reduce rodent infestation. Store pet food in sealed containers and do not leave it out at night
  • Use proper garbage and refuse disposal containers and implement exterior sanitation programs
  • Remove fruits or nuts that drop in backyards. Strip and destroy all unwanted fruit when the harvest period is over
  • Do not permit landscapers to arrive at your property with cuttings/clippings from other customers. The rats can migrate from area to area in haul-away trimmings carried by landscapers.

How should I handle dead rats, rat droppings, and nesting areas?

  • Use rubber gloves
  • Ventilate the affected area the night before cleanup by opening doors and windows
  • Spray dead rats, droppings, nests and surrounding areas with a 10% bleach solution (one-part bleach and 9 parts water)
  • Allow at least 15 minutes of contact time before removal
  • Clean the affected area with paper towels or a mop
  • Do not sweep or vacuum. Double bag both the disinfectant-soaked rat and cleanup materials securely in plastic bags and seal
  • Dispose in city trash containers
  • Before removing gloves, wash in disinfectant, then soap and water
  • Dispose of gloves with other household waste. Thoroughly wash hands with soap and water

When do they travel?

  • During twilight and nighttime hours in a territory 200 to 300 feet from their daytime nesting locations
  • They thrive in cool weather and are most active from November through May

What do they eat and drink?

  • They love to eat citrus fruit (because it serves as both a food and water source) and other fruit (pomegranates, figs, etc.)
  • Nuts, seeds, stored grains, and vegetables in your garden
  • They also eat insects, lizards, tree bark, soap, paper, and beeswax
  • Dog and cat food left outside
  • Queen Palm tree fruits in the summer when citrus isn’t available
  • Water sources include leaky faucets, sprinkler heads, bird baths, fountains and ornamental ponds, condensation drip lines, saucers under potted plants, and pet water dishes
  • They will chew through metal and plastic pipes to reach water.

Eliminate Food Sources

  • Keep garbage containers tightly covered.
  • Store bulk foods in sealed, rat proof containers.
  • Do not leave pet food out, especially overnight.
  • Promptly pick up any fallen fruit from citrus trees, etc.
  • When possible, harvest your citrus crops promptly and completely

Control Roof Rats

  • Consult a professional exterminator.
  • Contact Maricopa County Vector Control at 602-506-0700 with questions about setting your own traps
  • Trap rats with large spring-loaded bait stations that you can purchase at hardware or feed stores
  • Eliminate other sources of food before trapping
  • Bait traps with peanut butter and place them in areas with known rat activity
  • Good trapping sites can be identified by the presence of rat droppings, gnaw marks or where you have seen or heard them in the recent past
  • Traps may need to be set in high places, like on awnings, roofs, balconies, etc.
  • Large sized traps can injure children and pets
  • If poison baits are used, use only products that are designed and labeled for controlling rats
  • Ensure poison baits are placed so as to protect children, pets and non-target animals

Manicuring Landscape

  • A clean yard is a deterrent.
  • Rake under your trees and shrubbery
  • Prune fruit trees so the ground under them is open and visible
  • Remove wood piles and brush piles from your yard
  • Store wood and lumber piles at least 18 inches above the ground and 12 inches away from walls
  • Thick ground covers should be thinned
  • Keep palm trees trimmed
  • Thin out bushes and bougainvillea until you can see daylight through them
  • Oleanders are particularly prone to harbor Roof Rats in the summer