Pest Control for Roof Rats

Latin Name for Roof Rats: Rattus rattus

Location of Roof Rats

The roof rat arrived in the Americas with early explorers in the late 15th century. Roof rats can be found in the south, central and coastal areas of the U.S.  In San Diego the roof rat is the most numerous and significant type of rat.

Biology of Roof Rats

Roof rats can weigh up to 8 ounces and grow up to 16 inches from nose to the end of the tail. The length of the tail is important in identifying a roof rat, and is characteristically longer than the rest of its body. The roof rat has a litter range from 6-12 young. In laboratories, rats have been kept alive for 2-3 years, but this is not common.

Foods of Roof Rats

Roof rats are omnivores, and will eat many types of food if available, but tend to prefer fruit such as oranges. When necessary, roof rats will cannibalize their young.

Habitat and Range: Roof Rats

The roof rat inhabits vegetation, exterior areas, and inside buildings.  The roof rat prefers treetops, roofs, attics, and walls, because of their adaptation to elevated areas for safety. Items that contribute to the infestation of roof rats include;

• Tree growth (Keeping trees off your home by several feet is critical)!
• Growth of shrubs and vines (This provides roof rats with the camouflage for them to feel safe).
• Woodpiles (They know they are unlikely to be followed into the woodpiles).
• Sheds (No one ever bothers them there)!
• Yard trash (There\’s plenty of food there)!

Rats are very adaptable, and so its\’ habits vary from place to place, however, rats have two peak periods of activity, near sunset and dawn. If you hear noises at dusk and dawn, it just might be a roof rat!

Predators of Roof Rats

Roof rat predators include hawks, owls, ferrets, weasels, coyotes, skunks, raccoons, and snakes. Contrary to popular belief, cats and dogs do not maintain control of rats. At the rate that these rats reproduce, you may be fooling yourself that the family pet has caught them all and in doing so prolong the problem!

Health Issues: Roof Rats

Rats can carry a variety of diseases.  If you come in contact with a rat or are bitten by one, contact your doctor immediately.  Historically, urban plagues have been spread by rats bitten by fleas. In recent years the plague has not been a factor, due to improved sanitation and antibiotics. To minimize the risk of plague, use insect repellant, and when handling wild animals wear protective gloves.

An additional disease carried by rodents is the Hantuvirus. Rodents can pass the Hantuvirus to humans through 3 main processes;

• Direct bites
• Coming in contact with something that has been contaminated with rodent urine, droppings, or saliva, and then by touching your nose or mouth.
• Food becoming contaminated through rodent urine, droppings, or saliva.

Although only the marsh rice and hispid cotton rats carry the Hantuvirus, you would be right to worry about hantuvirius and you should not immediately assume that you could not contract a disease. It may not be hantuvirus, but there are plenty other nasty illnesses spread by rats, and you should not try to discerning what species of rat was on the attack.  Neither the marsh rice rat nor the hispid cotton rat reside in California.

For more about rat contamination and cleanup / cleanout and restoration, see our page on mites and parasites associated with rat and bird infestations, as well as our general page on rats and mice. Both these pages graphically depict contamination, exclusion and cleanout efforts.

Pest Control for Roof Rats

Identification: A Norway rat is larger and thicker than the roof rat.  The roof rat has larger ears and a more pointed nose as well. Ten (10) signs a rodent may have infested are;

• Feces(droppings)
• Gnawing damage
• Burrows
• Runways
• Tracks
• Grease marks
• Urine stains
• Visual sightings of live or dead rodents
• Rodent sounds
• Rodent odors

Non-Chemical control of roof rats: Once control is attained, non-toxic monitoring can be achieved through non-toxic bait blocks and the use of non-toxic foods. These can determine whether the infestation is still present.  Rodent proofing (exclusion) and sanitation are effective ways to prevent future entry of rodents.  Mechanical traps and glue traps are both available, but mechanical is the safest and most effective method. Hearts Pest Management endorses the use of mechanical snap traps as the quickest and the most humane way to eliminate rats. We have found tremendous damage done by individuals leaving rodent bait for rats, especially when left indoors, where rats die and create above ground cemetery conditions in attics and sub-areas.

Chemica control of roof rats: Rodentcides exist, but there are many reasons mechanical traps are generally preferred including;

• It can take 3 to 10 days to kill a rodent with rodentcide baits, during which the rodent will continue to contaminate the area with fecal pellets, urination, hairs, and gnawing. With mechanical traps the rodent is captured once and prevents this problem.
• Rodenticides are toxic and can be spilled, carried away, or blown into the wind, all of which could transfer the chemical to non-target sites and possibly contaminate food.
• When used correctly, captured rodents will not die inside a wall, which prevents odors and other types of infestations..
• In most cases, rats can be eliminated using only traps and without the use of rodenticides.

Hearts Pest Management endorses the use of rodenticides only for the outdoor control of rodents such as roof rats, but only once we are sure that the home or business has been excluded from rat entry. We do not want rodents to travel while ailing and die inside the structure. Outside, after proper exclusion, this may be the best method to keep down the population of roof rats that migrate from nearby canyons and fields.

When chemical treatments must be used, anticoagulants are commonly the method. Anticoagulants cause death as a result of internal bleeding. The most used non-anticoagulants are:

• Zinc phosphide: Attracts rodents and causes them to die from heart failure from within 17 minutes to several hours. It is commonly implemented as bait against roof rats and mice. (Hearts Pest Management does not use zinc phosphide, as it has no antidote)!
• Bromethalin: Causes death within 3 days due to a decrease in cellular energy production, which causes the animal to become weaker over several days. On rare occasions secondary hazards have been reported in cats, however if non-lethal doses are consumed the toxic effects are reversible.
• Cholecalciferol: Disrupts kidney functions.  Cats and Dogs are susceptible to its effects, so when an animal is present this is not a potential choice.

Rat Control for Roof Rats – Testimonial

“Dear Allision,

I couldn’t believe it!

When I called Hearts with a roof rat attic problem Tony Perez came out and made a thorough inspection of the site. He then advised me how to solve my problem with the understanding that I would call him back if it did not work.   One week later it appears that the problem is solved.

I am eighty years old and have dealt with service people innumerable times. Tony ranks at the top in his competence, attitude and desire to please the customer.

Your company is to be commended if Tony’s performance is indicative of how all of your employees fulfill their duties.”

Thanks,

Al W.

Poway, CA

For our full testimonial webpage, click here.

Roof Rat – Sources

Bachleda, Lynne F. Dangerous Wildlife in California and Nevada. Birmingham: Menasha Ridge Press, 259.

Mallis, Arnold, Handbook of Pest Control: The Behavior, Life History, and Control of Household Pests, 9th ed. University Park: GIE Media, Inc. 2004. 18-82.

R.E. Marsh, T.P. Salmon, and R.M. Timm, “Rats: Integrated Pest Management in the Home and Landscape,” Pest Notes: University of California Agriculture and Natural Resources, ed. B. Ohlendorf 74106 (Jan 2003): 1-2.

Sullivan, Lawrence M. \”Roof Rat Control around Homes and Other Structures.\” University of Arizona, AZ1280 (March 2002): 22-26. ag.arizona.edu/pubs/insects/az1280.pdf

Lawrence M. Sullivan, “Roof Rat Control around Homes and Other Structures,” University of Arizona, AZ1280 (March 2002): 22-26. ag.arizona.edu/pubs/insects/az1280.pdf (accessed June 4, 2008).

Mallis, Arnold, Handbook of Pest Control: The Behavior, Life History, and Control of Household Pests, 9th ed. (2004), 29.

Mallis, Handbook of Pest Control, 28-30.

Sullivan, Roof Rat Control, 3.

Mallis, Handbook of Pest Control, 34

Mallis, Handbook of Pest Control, 29-32.

Mallis, Handbook of Pest Control, 29.

Mallis, Handbook of Pest Control, 30.

Mallis, Handbook of Pest Control, 49-50.

Mallis, Handbook of Pest Control, 28.

Mallis, Handbook of Pest Control, 18.

Lynne F. Bachleda, Dangerous Wildlife in California and Nevada (Birmingham: Menasha Ridge Press), 259.

Bachleda, Dangerous Wildlife, 260.

R.E. Marsh, T.P. Salmon, and R.M. Timm, “Rats: Integrated Pest Management in the Home and Landscape,” Pest Notes: University of California Agriculture and Natural Resources, ed. B. Ohlendorf 74106 (Jan 2003): 1-2.

Mallis, Handbook of Pest Control, 51.

Mallis, Handbook of Pest Control, 58.

R.E. Marsh, T.P. Salmon, and R.M. Timm, “Rats,” 4.

Mallis, Handbook of Pest Control, 74.

Mallis, Handbook of Pest Control, 76.

Mallis, Handbook of Pest Control, 80-82.

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