Dealing with Roof Rats

There are several steps homeowners can and should take to prevent and minimize the rodent's length of stay and possible ensuing damage:

1. HOME PROOFING: Seal House and Attic

2. LANDSCAPE CARE: Trim and manicure trees and bushes.

3. FOOD & WATER SOURCES: Glean fruit trees, secure pet food and water sources.

4. PROTECTION AND ERADICATION: .eRATication that works!"

5. WORK WITH NEIGHBORS: All of us helping each other and working together will clear our neighborhoods of this common enemy. Go to "Neighborhood Action"

HOME PROOFING

• The most extensive damage occurs when roof rats enter the home, so the first goal is to keep them out!

• Caulk all holes, cracks, crevasses, or gaps (any opening larger than a nickel) on the exterior walls and underneath the eaves of block and/or wood constructed homes/outbuildings, sheds, etc.

  • Look for holes in exterior walls and near hot water heaters, washers, dryers, dishwashers, and under sinks.

• Roof vents and attic turbine ventilators should be checked and screened if necessary.

• Fireplaces need to be protected with the proper screening of a chimney cap.

• Tile or wood shake roofs should be closely inspected for openings.

• Pet doors, vents, and exterior door and window screens should be secured at night.

• Use stucco diamond mesh or steel wool and a flathead screwdriver and push the material into prevent rats from climbing up the insulated pipe inside the cover. Look for scratch marks on the insulation, and then set a snap trap to catch them the next time they use that entrance.

• Always shut doors when exiting/entering the home.

• Screens placed on clothes dryer vents should be checked often and cleaned for accumulated lint. Not cleaning the screen could result in the malfunction of the dryer and/or possibly result in a fire.

LANDSCAPE CARE

• Roof rats are not indigenous to Arizona, and therefore try to escape the heat by harboring in thick shrubs where there is moisture and protection; a clean yard is a deterrent.

• Thin out bushes until daylight can be seen through them; oleanders and bougainvilleas are particularly prone to harboring roof rats.

• Prune trees and shrubs up from the ground at least 12 inches so the ground beneath is open and visible.

• Prune back all tree branches from all structures by at least 6 feet.

• Rake dry leaves, old growth and weeds from under trees and shrubbery.

• Thick ground covers should be thinned.

• Keep palm trees trimmed. Roof rats nest in the skirts of old fronds, as well as in piles of debris and hollow trees.

• Take down all vines/shrubs growing against the home or perimeter walls

• Remove wood and brush piles from yard.

• Eliminate piles of lumber and firewood, or store them at least 18 inches above ground and at least 12 inches from walls.

FOOD AND WATER SOURCES

• Promptly and completely pick all fruit (ripe or not) on citrus and other fruit and nut trees, and pick up fallen fruit every season.

• Fruit and nut trees that touch other trees, houses, fences or power lines have more roof rat activity, so prune to isolate each tree.

• If you can’t physically pick your trees, go through the yellow pages for landscapers who might. Those landscapers who will pick – not all do – typically charge between $20 - $45 per tree.

• Residents can also call their faith community for youth groups who might be looking for community service work or Boy and Girl Scout troops are a good example.

• Consider donating excess fruit to the nearest food bank.

• With proper care, fruit and nut trees do not need to be removed, but you may want to consider this if upkeep is not possible for you.

• Check for the seasonal citrus drop off program (generally from January to March each year). In a partnership between the city, residents and county agencies, the Arcadia Citrus Program makes citrus drop off possible, with viable fruit being distributed to food banks and county facilities.

• Short of cutting a nut tree down, there is virtually no way to stop a nut bearing tree from being a roof rat’s food source. But the tree will make a good place for a bait station (see section on bait stations and snap traps).

Don’t unknowingly feed roof rats

• Roof rats will eat anything to survive – this includes all domestic and wild animal food, garbage, and animal feces.

• Keep all pet feces off the ground at all times.

• Don’t leave pet food out, especially overnight.

• Consider not filling bird feeders until all signs of roof rat activity have ended, or provide just the amount of bird seed that will be consumed in a day and sweep up fallen seeds before sunset.

• Store bulk foods and seeds in metal, sealed, rat-proof containers. (Rats will eat through plastic bins.)

• Keep garbage containers tightly covered.

Eliminate water sources

• All water sources on private properties are a welcomed invitation to a roof rat. This can include birdbaths, dog/cat water bowls, fountains, water features, and pools.

• Drain or empty all standing water sources except pools and spas. Draining standing water also helps prevent mosquito breeding issues.

• Change pets’ drinking habits by training them to go inside for a drink, if your dog/cat is used to drinking water from a bowl outside.

• Do not leave food or water outside for stray/neighborhood animals.

• Keep pool water level at least 6 inches below the decking surface. If a rat falls in while getting a drink, it won’t be able to get out of the pool and can drown. Dead rats can be fished from the pool with a long-handled net and all questionable areas, to screen and seal all holes and air vents leading into the home or shed. It cuts and molds very easily. For aesthetic purposes, you can use paintable caulk to go over the areas containing the steel wool and then paint over the caulk.

• If window or door screens are loose, either reinforce or replace.

• Stuff the cover of the air conditioning line that runs from the outside unit into the attic with steel wool or copper mesh to disposed of in city trash containers.

SNAP TRAPS

Large spring traps by Victor, best baited with peanut butter and a secured nugget of nut or pet food.

POISON BAIT

Use recommended poison for roof rats, securing bait in a Personal Use Bait Station (PUBS) or a commercial bait station which keeps pets, wild birds and children safe.

RAT ZAPPER

A quick electrical shock instantly kills the roof rat, best used in attics and around the home. To order, visit cheapzappers.com.

LIVE TRAPPING

"Have-a-heart" traps will catch live roof rats. Rats need to be exterminated and not moved from the subject property. Maricopa County Vector Control (602) 506-6616 may pick up any captured live rats upon request only when staffing allows.

GLUE PADS

Not effective for adult roof rats, though this method does work for mice and rodent young.

STROBE LIGHT AND ULTRASONIC DEVICES

For the most part ineffective, these devices do not detour rats from an attic or storage space.

SNAP TRAPS

Snap traps (designed with a trigger mechanism) can be purchased at home improvement stores.

Snap traps (like those used for mice) are intended to be baited with a food source and to kill the rat as the rodent attempts to eat the bait. These traps must be emptied of the dead rodent and reset after each use. They are recommended for use only in areas where bait stations are not feasible, such as inside the home.

How to bait and deploy snap traps

• • Bait snap traps “lightly” with creamy peanut butter so the rat will have to work hard to get it off the trigger, which will ensure that the trap will ‘trip’. OR…

  • Bait snap traps with a mixture most people can make in their own kitchen (dry oats, creamy peanut butter, and nuts or peanuts). Mix the oats and creamy peanut butter together in a bowl until it reaches the consistency of cookie dough. Roll a small “dough ball” in the hands (about the circumference of a quarter). Slip the nut of choice into the middle of the “dough ball.” Re-roll the ball a bit in the hands. Place the “dough ball” (AKA: “bait”) on the lever of the snap trap where the “bait” is designed to rest. Use dental floss to “tie down” or secure the “bait” to the lever (the nut inside the “bait” will keep the dental floss from going completely through). It is important to secure the bait onto the trap’s lever to prolong the time the rat will spend at the trap. Often, the rat is quick enough to evade a lethal snap, hence defeating the trap’s purpose.

  • Any questions regarding the proper deployment of snap traps should be directed to the trap manufacturer.

  • When used in attics, snap traps should be placed within arms length of the entrance into the crawl space/attic.

  • It is also recommended that each snap trap be secured down to the wood framing/rafter within the attic. If a rat evades the lethal snap of the trap, yet is still caught in the apparatus, the rat can potentially scamper away connected to the trap to die elsewhere in the attic, thus causing an unnecessary odor and expense to the homeowner.

  • Check snap traps daily, but don’t move or disturb them if there is no rat captured. Roof rats are nervous and cautious of new objects, so leave snap traps in the same location for at least a week without physically disturbing them, unless a rat has been captured.

Snap Trap Safety Precautions

Only place snap traps well away from children and pets

Use snap traps in any crawl space or attic. These mechanical traps are spring loaded and are constructed of wood or plastic. They can be purchased at most home improvement stores for a few dollars.

Snap traps come in two sizes (small and large). The small are for mice and the large are for rats.

BAIT STATIONS

Personal Use Bait Station (PUBS) Instructions

The bait station is ideal for people who have lush landscapes, unpicked citrus, pecan trees, figs, date palms, pomegranates, apples, peaches, apricots, as well as any human or animal food source. The roof rats are attracted to these areas because of water, food, or shelter and are prone to take the poison bait. Please see the Bait Station page for more information about placement, monitoring, and where to obtain bait, etc.

• • Before setting bait and bait stations, it is imperative that you properly seal your house to avoid poisoned rats from entering the house and dying, creating a bad odor which may be hard to remove.

  • Bait stations are for “housing” toxic bait, not for trapping the roof rat. The roof rat enters the station, eats the bait, and then leaves. Within 3-6 days after ingestion, the poisoned rat dies.

  • Bait stations provide a protected place for rats to feed. They allow residents to place poison bait in some locations where it would otherwise be difficult because of hazards to small children and/or non-target animals.

  • For bait, use the anti-coagulant ingredient “Bromadiolone” which is sold as “Just One Bite” and can be purchased at feed and hardware stores.

  • Residents are responsible for purchasing and placing the bromadiolone poison in the bait station. Read the entire label first and strictly adhere to all instructions, restrictions, and precautions.

  • Place two or more bait stations in your yard, depending on the size of the property and the number of trees and shrubs.

  • Optimal locations are in trees and on any potential rat pathways, such as shrubs, perimeter fences and roofs.

  • Use a metal strap to secure bait station to a tree or wall with screws or nails.

  • Place the station’s entry point in a slightly upward position. The bait station is most effective from 4’ to 6’ above ground at no greater than a 25-degree angle.

  • Install unit where it is easy to inspect for any rodent activity.

  • Normally, birds will not seek out or be attracted to bait that is properly enclosed in bait stations; however, if you are concerned, you may choose to close the bait station openings in the morning to protect wild birds, and open them in the late afternoon about sunset.

  • The practice of wiring poison bait “blocks” directly to tree branches without a bait station may cause accidental poisoning of cats and wildlife; use poison bait blocks only in bait stations and slide the blocks all the way to the back.

  • It is recommended to check and refill bait stations at least weekly and they may need to be checked up to daily during times of heavy use.

  • Bait stations should be deployed and monitored year round.

  • See the section on handling dead rats, rat droppings, and nesting areas for complete instructions and safety precautions.

PUBS and Poison Bait Safety Precautions

• • Place bait stations well away from children and pets!

  • Always read and follow all bait manufacture’s handling instructions and precautions.

  • In case of emergency regarding bait, call the local Poison Control Center at (602) 253-3334.

  • Toxic bait should never be used in the home or in the home’s crawl space. For these areas, see the section on snap traps (below).

POISON BAIT

Rodenticide Used: Bromadiolone

• • Registered with the U.S. Environmental Protection Agency (EPA) and recommended for use in alleys for roof rats.

  • Newer class of anti-coagulant with extremely low level of active ingredient.

  • Anti-coagulant reduces the ability of blood to clot so that the rat bleeds internally and dies (usually within three to five days).

  • Each station will have eight ounces of bait (four two-ounce blocks), consisting of .005% rodenticide and 99.95% food substances like grain and flavoring.

Bromadiolone Toxicity Levels:

• • LD50>5000mg/kg. LD50 means 50% mortality rate when eating 5000mg/kg. The lower the LD50, the higher the toxicity.

  • Compared to Nicotine: LD50=53; Caffeine: LD50=192; Aspirin: LD50=1240; Table Salt: LD50=3320.

  • A 22-pound dog would have to eat nine pounds of bait (the full contents of 18 bait stations) to have a 50% mortality rate without treatment.

  • A four-pound cat would have to eat 2.5 pounds (the full contents of five bait stations) to have a 50% mortality rate without treatment.

  • Vitamin K1 is an effective antidote for anticoagulant poisoning.

  • Secondary effects: A cat would have to eat more than 30 poisoned rats to have a toxic effect.

Over the Counter Bait

"Just One Bite" or any anti-coagulant containing the active ingredient "bromadiolone" can be purchased at local livestock feed stores.

General Safety Precautions

Safety Precautions: Handling dead rats, rat droppings, and nesting areas

• • Roof rats throughout Maricopa County continue to test negative for tularemia (rabbit fever), Hantavirus, and plague, however the following procedures are recommended by the county:

  • Ventilate the affected area the night before cleanup by opening doors and windows.

  • Spray dead rats, droppings, nests, and surrounding areas with a 10 percent

  • bleach solution (one part bleach and nine parts water).

  • Always maintain adequate ventilation when spraying the bleach solution and allow at least 15 minutes for ventilation before removing anything from the sprayed area.

  • Use rubber gloves and wear a face mask when handling dead rodents or when cleaning areas that they have inhabited.

  • Large zipper food storage bags can serve as a protective glove when turned inside out. The rat can then be picked up and pulled through the bag opening (making the bag right side out), zipped shut and thrown away.

  • 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 of 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 after disposing of all items.