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Here are the 5 warning signs of roof rats in the Phoenix metro

If there’s a “trinity” of pests here in the Phoenix metro, most experts would agree that bark scorpions and subterranean termites take the two spots. The third? Roof rats. Every Valley homeowner needs to know the warning signs of roof rats and when and how to take action.

In this article, we’ll introduce you to these pests and review how infestations take place. We’ll then discuss the common signs of roof rats, as well as how you should go about having an infestation removed.

What are roof rats?

Typically, roof rats are the black rat. Infamous for once spreading the bubonic plague to Europe, black rats are one of the world’s most successful and widespread species, living anywhere humans do.
Roof rats, as the name implies, make their nests in Phoenix area attics. They’re a specialized rat that has adapted to the modern lifestyle of humans here in the desert.

Why are they so common in the Phoenix metro?

Gilbert and Tempe are both in the top-5 for roof rats nationwide. There are many reasons for this, but one of the primary ones is that the citrus trees in many backyards in the Valley provide a consistent food source for rats, while attics are generally undisturbed by local homeowners.

How do they infest new homes?

Roof rats can travel in many different ways to new homes. According to researchers at the University of Arizona, rats move 200-300 feet at night and are most active in the cooler months of the year. Like most rodents, roof rats are most active at dawn and dusk, and try to avoid movement during the light and heat of the day.

Most homeowners see roof rats in the evening as they head out from their shelter in search of food.

True to their name, these rats are experts at traveling high up. They’ll move along power lines and can climb up brick and stucco. When they reach their destination, they can enter homes through any nickel-sized opening or larger. As we’ll discuss below, this makes denying shelter to roof rats complicated.

Are roof rats dangerous?

Potentially, yes. Roof rats are infamous disease carriers. Black rats are responsible for some of the deadliest and most infamous disease outbreaks in human history: in medieval Europe and Asia, ship-borne black rats carried fleas infected with bubonic plague to new cities, killing millions of people and changing the course of history.

While it’s highly unlikely roof rats here in suburban Phoenix have come into contact with plague—cases of which do happen here in Arizona in wilderness areas—they can carry several other serious diseases. This can include typhus, jaundice, salmonellosis, and rat-bite fever. These diseases can be spread to humans through exposure to droppings, urine, carried fleas, or—as you may have inferred—bites.

If you do come into contact with a roof rat or its nest, leave it alone and instead call in one of our rodent professionals. Only a pest professional, wearing proper protective clothing, should clean out or deal with a rodent colony.

Preventing a roof rat infestation

Like all pests, roof rats need regular access to shelter, food, and water. If denied these things, they’ll typically move on from your home to an easier target. Homeowners who take proactive steps to keep their yard clean, pick up food waste, and seal off entry points are typically less likely to have a roof rat infestation.

Denying shelter

True to their name, roof rats prefer to build their colonies in attics and roofs, where they are less likely to be disturbed by people and potential predators, such as feral neighborhood cats or barn owls. Once established, this colony can grow quickly. However, these rats are far from picky. They can also create their nests beneath wood piles, in storage boxes, under shrubs, and in garages and storage sheds. An unkempt yard with abandoned vehicles, multiple storage sheds, and overgrown bushes is just about paradise for a rat.

To prevent an infestation, start by cleaning up your yard. Keep bushes and trees trimmed down, taking special care to remove overhanging tree branches near your roof. Clean up any boxes or waste, and consider storing wood in an elevated and sealed-off place. If you have a garage or storage shed, keep it clean and orderly. Avoid storing cardboard moving boxes on the floor.

Denying sustenance

Roof rats are hardy and adaptable omnivores. During the twilight hours of late dusk and early morning, they’ll leave their shelter to find food. One of the reasons why roof rats have flourished here in the Valley is because of our abundance of backyard citrus trees. Fallen oranges, grapefruit, and lemons are the perfect nearby food source for rats. However, they’ll also eat seeds, nuts, snails, roaches, crickets, and any type of human food waste, such as dropped bread crumbs.

If you want to cut them off from the buffet line, you’ll need to be vigilant about picking up dropped citrus in your backyard and regularly harvesting ripe citrus fruit from your trees. If you feed your pets outdoors, pick up their food as soon as they’re done. Close any outdoor garbage bins. This is a long-term strategy: like their distant pack rat cousins, roof rats are hoarders who will build up a “pantry” in their shelter to sustain them through lean times.

Denying water

Here in Phoenix, this might be the hardest element to control. Our homes have introduced incredible amounts of water to the natural landscape, from our sprinkler heads to our AC condensate drip lines. However, cutting down on standing water can help. Fix irrigation line leaks to prevent water from pooling around plants and trees, and pick up pet water bowls when they are not in use.

What are the common signs of roof rats?

In most cases, a homeowner finds a rat—either dead or alive—inside or outside their home. Roof rats are social creatures who live in colonies, so never assume that one rat is just a random occurrence. You’ll want to take action.

Even if you don’t see a rat, there might be other prominent signs of roof rats around. Here are just a few things to look out for:

Fallen, half-eaten fruit

If you have citrus trees on your property, look at fallen fruit. If the fruit is eaten or hollowed out, that probably means rats have been feasting on it.

Strange noises in the attic

You’ll often hear roof rats making noises in their nests in your attic. In the still of night, listen carefully. If you hear squeaking or scratching coming from your attic, it might be roof rats above you.

Odd pet behavior

If you have cats or dogs that are acting strangely—especially toward the ceiling—that might warrant a closer inspection. Our pets can typically pick up on the scent or sounds of roof rats long before we can.

How do you check for roof rats?

If you suspect you have roof rats, do not personally inspect your attic. Roof rat droppings, urine, and nests can contain dangerous bacteria that can make you and your family very sick. While rare, roof rats can also act aggressively when cornered or confronted in their colony. If you have seen a rat or have seen evidence of their presence, you’re at the point where you should bring in a pest professional for an inspection. Here in the Valley, our team at KY-KO Pest Prevention offers free roof rat inspections.

Getting rid of a roof rat infestation

This requires the expertise of a licensed and experienced pest professional—someone who has worked with a roof rat infestation before. Removing an infestation isn’t just about laying down some traps and calling it a day. It requires a strategic approach that focuses on removing the current infestation and denying food, water, and shelter to roof rats. In other words, one of our pest control experts can help you figure out how to kick your current roof rats out and then keep them out.

In our experience, a strategic combination of traps, home sealing, and habitat denial tends to work. On their own, approaches like the use of poison or “rat-catcher” cats do not end an infestation, and tend to introduce new sets of problems and issues. We recommend you talk to a rodent professional and avoid any do-it-yourself shortcuts. They just tend to not work.