How to Deal With Roof Rats

We've Got Rats! Now What Do We Do?

Rat in temple
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The roof rat's scientific name is Rattus rattus. Historically, they are associated with having spread the plague or black death during the Middle Ages. The roof rat is also known as the black rat, even though it is not necessarily black in color, but rather is usually dark brown. Your typical roof rat is between 13 to 18 inches long, including its tail. In fact, it is distinguished from other rats by that tail, which is longer than the rest of its body.

Roof rats are sleek, slender, and agile.

Roof Rats in the Phoenix Area

Unfortunately, there are roof rats around Phoenix. The rat outbreak first occurred in the Phoenix area in 2001 when they appeared in the Arcadia neighborhood in east Phoenix. In 2004, there were confirmed roof rat sightings in Phoenix, Tempe, Glendale, Paradise Valley, and Glendale.

Roof rats are not unique to the state; they are partial to warmer climates. The roof rat has been found along the southern Atlantic and Gulf coastal states from Virginia to Texas and throughout Florida. They also are found along the Pacific Coast of California, Washington state, and Oregon. So how did they get to Arizona? In cars, in trucks, by movement of plants and trash—it's still unknown.

What to Know About Roof Rats

There are some easy signs to figure out if you have roof rats. Make sure you know what to look for.

  • Roof rat droppings are long and cylindrical.
  • Roof rats are nocturnal.
  • Roof rats can transmit diseases like the bubonic plague and typhus. At this point, none of the roof rats captured and tested in Maricopa County have been diseased.
  • Roof rats will enter homes and buildings. They only need a hole the size of a quarter to gain entry.
  • Roof rats are good climbers. They can climb walls and use utility lines and fences to travel from structure to structure.
  • Outside, roof rats will nest in trees, woodpiles, garbage, and plants. In Arizona, oleanders seem to be a popular nesting location.
  • Inside, high places, like attics, are their preference.
  • Roof rats do not burrow in the ground or swim.
  • Roof rats eat fruits, vegetables, nuts, pet food and invertebrates (spiders and worms, for example). They will also eat paper.
  • Female roof rats can each have up to four litters a year, each containing five to eight young. In urban areas where they have no natural predators, the survival rate of the babies is high.
  • If you have the following items around your home, you may be more prone to attracting roof rats: palm trees, yucca plants, pampas grass, honeysuckle, Italian cypress trees, any heavy shrubbery, wood piles, and storage boxes.

How to Tell If You Have Roof Rats

If you have citrus trees, and you notice hollowed-out fruit on the ground or in the trees, this is an indicator that roof rats are present. If you hear gnawing or scratching sounds in the attic or in the walls, you may have roof rats. Pay attention to any droppings in attics and storage areas. If you notice oily rub marks on the house or small holes in the screens, you could have roof rats.

How to Prevent Roof Rats From Moving In

  • Repair any broken or torn screens.
  • Keep your trees trimmed, and your bushes and vines thinned. Make sure trees are trimmed back from the house at least 4 feet.
  • Keep lids on garbage cans.
  • Clean up debris in the yard and storage areas.
  • Seal around your attic.
  • Don't leave pet food outside, especially at night.
  • Pick your citrus as soon as it is ripe. Remove any fallen citrus from the ground.
  • Store wood at least 18 inches above the ground and 12 inches away from the walls.
  • Eliminate standing water and fix leaky faucets.

How to Get Rid of Roof Rats

Trapping roof rats seem to be the preferred method of control, especially if you have small children or pets that might be affected by poisons. Snap traps are widely available. Several city offices are offering traps at very reasonable prices for their residents, as part of their education and prevention program.

Check the website of the city/town in which you live for more information about traps and their availability.