Roof Rats
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 PLEASE NOTE: The appearance of roof rats is
NOT a sign of neighborhood deterioration. They are NOT spreading
incrementally block-by-block throughout the Valley. For example,
these creatures can be unknowingly stored away in moving boxes
by someone relocating from another area. They seek neighborhoods
that meet their needs. So be sure yours doesn’t!
What are common signs of roof rat activity?
- Visual sightings on power lines, trees, bushes, patios,
etc.
- Hollowed out citrus and other fruit
- Rat droppings
- Noises in the attic and walls
- Gnawing sounds and gnaw marks around roof eaves
- Damage to plastics and coverings on electrical wires
- Unsettled pets
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What do I do if I see evidence on my property?
Call the Maricopa County Vector number 602-506-6616 - hit #3 and
report under the category of "Smoking automobiles and other
environmental issues" or visit
http://www.maricopa.gov/EnvSvc/VectorControl/RR/RRInfo.aspx.
How to handle dead rats, rat droppings, and nesting
areas [Taken from Marin/Sonoma Mosquito and Vector
Control District handout]
- 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.
Where have roof rats been found?
In swimming pools, laundry rooms, attics, garages and patios.
They’ve been seen on power lines in the alleys. Roof rats spend
90% of their life 4 feet or more off the ground.
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.
How do they travel?
Roof rats are strongly arboreal and travel along power lines to
trees, oleanders, vines and roofs. They can climb up brick walls
and other rough surfaces. They can jump 2 feet straight up and 4
feet horizontally (double the horizontal distance if they are
jumping from a height). Bear in mind that ground covers and
compost bins also provide safe travel routes and nests.
How do they enter homes?
They enter homes and garden sheds through any opening larger
than a nickel. They follow pipes down from the attic, gnaw
through drywall and enter the kitchen or base sink cabinets.
They chew through wood, plastic, aluminum siding, sheet rock and
soft metals.
Why attics?
These rodents are fond of attics because they provide a safe
refuge, a nesting place for their young and routes into the home
below.
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 and stored grains, and vegetables in
your garden. They also eat insects, lizards, tree bark, soap,
paper, hides, and beeswax.
Birdseed (both in feeders and stored in bags) and dog and cat
food left outside after dark are favorites. Roof rats eat Queen
Palm tree fruits in the summer when citrus isn’t available.
Water sources include leaky faucets and sprinkler heads,
birdbaths, fountains and ornamental ponds, irrigation, air
conditioner condensation drip lines, saucers under potted
plants, and pet water dishes. They will chew through metal and
plastic pipes to reach water.
How do I seal my home?
The most extensive damage occurs when roof rats enter the home,
so the first goal is to keep them out.
Use stucco diamond mesh available at building material
suppliers to screen and seal all holes and vents leading into
your home or garden shed. It cuts and molds very easily. For the
rat, this mesh is like biting into small razor blades.
Look for holes in exterior walls and near hot water heaters,
washers and dryers, dishwashers, and under sinks. Don’t forget
to screen off the sewer stacks on the roof.
All cracks should be caulked.
Stuff the cover of the air conditioning line that runs from
the outside unit into the attic with steel wool or copper mesh
to prevent rats from climbing up the insulated pipe inside the
cover. Look for scratch marks on the insulation, and then set a
snap trap there to catch them the next time they use that
entrance.
Harvesting citrus and other fruit
Pick all fruit (ripe or not) on citrus and other fruit and nut
trees and pick up any fallen fruit. Do this promptly and
completely. Fruit and nut trees having the most activity are the
ones which come in contact with other trees, houses, fences or
with power lines running through.
Donate any excess fruit your family won’t be able to eat to the
closest food bank.
Next winter, when the roof rats are under control or eradicated
altogether, enjoy your harvest, but be sure to pick your fruit
promptly and donate what you can’t use. You don’t need to remove
fruit trees from your landscape.
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 woodpiles 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 your palm trees trimmed. Roof rats nest in the skirts of
old fronds, as well as in piles of debris and hollow trees.
Thin out bushes until you can see daylight through them.
Oleanders are particularly prone to harbor roof rats in the
summer. Thin bougainvilleas as well.
Don’t feed them!
Don’t leave pet food out, especially overnight. Keep dog feces
picked up.
It would be best to stop filling your bird feeders for the
next few months. Otherwise, provide just the amount of birdseed
that will be consumed in a day and sweep up fallen seeds on the
ground before sunset. Store bags of birdseed in sealed,
rat-proof containers.
Store bulk foods in sealed, rat-proof containers.
Keep garbage containers tightly covered.
Long-term solutions
Strongly consider xeriscaping your yard. Xeriscape doesn’t have
to be gravel and a couple of cactuses. There are many lovely
options. Combine xeriscape with a citrus-free yard to create a
very effective control against roof rats. Maintain a defensive
line on your property by continuing the use of bait stations,
keeping a clean yard and removing pet food and water dishes at
night.