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The Essential Guide to Rats

essential guide to rats cover FINAL

One of the most common pests around the world is the rat. These long-tailed rodents are found in all corners of the world, except for areas like the Arctic Circle or Antarctica.

Infamous pests, rats target kitchens, spread diseases and are even known to bite people. The crafty rodents also breed fast and can infest a home or building quickly. Rats are known to hitch rides in goods transported by ships or planes.

In the Essential Guide to Rats, we look at the most common questions asked about rats and provide answers so you can know everything you need to know about rats. If you think you have rats on your property, contact Ehrlich.

Click on the questions below and be taken right to the answer.

Rat information

Rats as pests in homes

Risks of rats 

Rat information

What is a rat?

Rat eating

A rat is a medium-sized rodent related closely to mice, as well as other rodents, such as shrews and moles. They are part of the mammalian order called Rodentia. They are very adaptable rodents, which means they have become populous around the world, existing in all areas of the world except for extreme areas such as Antarctica. Because rats are able to adapt to their environment so easily, they have become one of the most common pests and have been around for millions of years, likely living exclusively in the wild at one time, then adapting to humans as they gained prominence in the world.

Where do rats come from?

It is unknown for certain where rats originally came from. However, there are theories that rats might have originated somewhere in Asia. This is particularly true of the species of rat known as the Norway Rat and the Black Rat, which are two of the most prominent rats in the world. They soon hitched rides on ships and within containers as Asia was reached by Europeans and quickly populated Europe and other areas of the world. When humans then expanded to the Western hemisphere, rats once again stowed away on cargo and ships and came ashore, starting up new populations in North and South America.

Where do rats live? Where do rats live in the wild?

Rats live in a variety of places. There are rats who live in the wilderness such as woods and forests, as well as fields and meadows. There are wild tree rats that live on tropical islands and they are invasive species and have taken over entire populations of wildlife. In the wild, rats eat vegetation and other small animals meat.

However, rats have also adapted very well to populated and urban areas. They have come indoors by using openings or chewing openings in siding, wood, and even some kinds of stone. They get into office buildings, warehouses, apartment buildings, restaurants, hospitals, and homes.

Rats will live inside walls as well as attics and basements. They look for warm places to nest and for an easy access to food sources as well as material necessary to build nests and breed.

Some rats even live in sewers and underground. They can crawl their way through pipes and find their way into homes and buildings from the sewers, too. They even live peacefully and effectively in darkness and underground areas like subways and maintenance tunnels.

Rats are very adaptable and are capable of living in nearly any condition. They can live in lighted areas, without light, in warm and moderate temperatures and can find warm areas to live even in areas where there is winter. As long as they can find access to food, they can exist in nearly all conditions.

What do rats look like?

Rats are mid-sized rodents that come in a variety of colors. Sometimes they are brown, sometimes gray and even black. They are covered with fur from head to their tail. They have very long tails that are not covered in fur.

Rats have small paws and an elongated head with a narrow nose and whiskers. Rats also have large front teeth, which grow constantly, so they need to chew on things in order to keep them in check.

The exact look of a rat depends on the species. The species of rat will determine the size, whether or not there is fur in their ears or paws, and whether or not the rat is round or more slender than other rodents. Event the length of the tail can vary based on the species.

What color are rats?

Rats come in a variety of colors and most of the time it’s the species of rat that determines the kind of colors. Some of the colors found among species of rats include:

  • Black

  • Brown

  • White

  • Red

  • Gray

  • Spotted and multi-colored (most often in rats bred as pets)

Their fur is one of the colors listed above, but their eyes are usually black or red and their paws and tails are usually pink. Of course, there are variations of those colors, too.

Why do rats squeak?

Rats and mice squeak and make a variety of noises. They do so to communicate emotions, talk with other rodents and rats and provide warnings. It is thought rats squeak, hiss and chatter their teeth as warnings and to indicate pain or fear.

Rats will also grind their teeth, which can make noises, and they will chew on wires, wood and other substances in the walls. They also use their paws and claws to scratch things, which will also make noise.

Where do rats hide?

Rat hiding in a pipe

Where a rat hides, depends on where the rat lives and what species of rat it is. There are rats that prefer to live in the wild and there are rats that live in and around human habitats. It’s seeking shelter that rats are usually trying to do when they end up inside your home because they are generally shy creatures and don’t want to be seen or disturbed.

Rats in the wild will hide in old logs, hollowed out trees and many species of rat (such as the brown rat) will burrow into the ground. They create shelters and chambers underground to store food and for nesting and raising their young.

When it comes to rats who are in urban areas and around people, they will find anyplace they can to hide, breed and find food. This includes attics, basements, between walls, beneath piles of old boxes, clothing or other debris. They will chew through walls to get between them and use the space between interior and exterior walls for shelter.

Rats and other rodents will find any place they have easy access to food and where they can find warmth. They tear apart insulation, newspaper, garbage and other items to create soft nests so they can sleep, rest, breed and raise their young.

The thing to remember about rats is that they have flexible skeletons. This means they can crawl through even the tiniest of cracks, holes, and spaces, to get inside. This does no damage to them and they can stay compressed as long as necessary, so if you find signs of rats and think a possible hiding space is too small, check it anyway.

What do rats eat?

Three dirty mice eat debris next to each other eating out of trash

Rats are very opportunistic creatures and will eat a wide variety of things. They are often referred to as omnivores, which means just about anything they can bite and chew, they will eat. They do have a preference for sweet things and proteins.

What a rat eats depends on a lot on where they are living. For example, rats in the wild will eat different things than those who find a spot near humans. Wild rats will eat grains, mostly, and some eat fruits, tomatoes, garden tomatoes, melons and other sweet things. Some wild rats also eat meat and fish.

What do rats do?

Rats just want to eat, stay warm, breed and live their lives in peace. They prefer to be left alone, but the fact is they have adapted to living with people. Before humans built homes in wooded areas and made it so rats had to adapt to this incursion into their territory, rats lived in trees, burrowed underground, lived in old, fallen logs or other vegetation.

However, rats have had to adapt to humans who have moved and built in their territory. This means rats will get into walls, find their way into basements, sewers, plumbing, and openings in walls, siding roofing, open doors and other areas. They use their ability to squeeze into the smallest spaces to get inside and find places where they can do what they love to do.

Rats want to find a good and consistent source of food. Rats want to find a place where they can hide and build their nests. Rats want to breed, feed themselves and their young, like most animals.

What is the lifespan of a rat?

The lifespan of a rat depends on the species of rat and if the rat is kept as a pet or if they are in the wild. A lot also depends on where the rats live and the situation they find themselves in.

Domestic rats

Rat kept as pet sleeping

Many people like to keep rats as pets. For those who do not keep “feeder rats” which are actually kept to feed snakes and reptiles, most average species of domestic rats will live a little over a year. There are also those types of rats who are specially bred, known as Fancy Rats, which can live 2 or 3 rats.

Wild rats

Wild rats tend not to live their full life expectancy. This is because rats are often food for predators and, of course, people who get treatments for rats which eliminate them. In the wild, most rats would consider themselves as geriatric if they lived a year or more than a year.

When do rats come out?

Rats, like a lot of rodents, will come out if they are disturbed and if they need food or something urgent. However, rats are generally nocturnal. You will see rats come out into your home, in dumpsters and garbage, generally, they get more active at night. The darkness helps protect them from predators, including people. However, there are also nighttime predators that are fond of rats, such as owls. However, if you have a rat infestation, you are probably more likely to see them or see signs of rats at night, or in the early morning when you wake up and see the damage rats leave behind overnight.

Why do rats exist?

Rats are rodents that do actually serve a purpose in the ecosystem. They are scavengers and opportunistic eaters. They will eat garbage and other things that people throw away. Plus, rats are important as part of the predatory ecosystem. Owls, falcons, hawks, and other predatory animals feed on rats. The animal ecosystem is a delicate balance and losing on an element within it can be detrimental to the entire system. Some lizards, reptiles, and snakes prefer to feed on rodents such as rats, for example.

How many species of rat are there?

Rats are part of the species or genus known as Rattus. There are 51 documented species of rodent within the Rattus genus.

Are rats dangerous? What diseases do rats carry?

The fact is rats can be dangerous to humans. While they are not poisonous and do not have fans or anything like that, they are known to bite and their bite can contain bacteria which can be harmful to humans. However, it’s not just bites that are the health risks from rats. Rats are also known to be vectors for a number of diseases for a variety of reasons.

Some of the rat-borne diseases include:

  • Hantavirus – a very dangerous disease that is carried in the rat urine from the rice rat. They can be found in places like the Western United States. Rat urine will dry and turn to dust, potentially infecting you with the virus. Hantavirus is also contained within rat feces and can even be transmitted via rat bite.

  • Rat-bite fever – a dangerous disease which is transmitted by touching rats or being bitten by a rat. It causes an inflammation of the skin and a fever which can become dangerous.

  • Salmonella – also known as food poisoning. Rats like to wander around kitchens and areas where food is prepared and they also like to tromp through garbage and feces in areas where there are garbage and areas of the property where they reside. This can lead to contamination of food preparation areas and the food itself, leading to salmonella contamination which can be fatal if serious enough.

  • Leptospirosis – a bacterial disease which can be transmitted by an infected animal and the disease causes fever, chills, muscle aches, headaches and even bleeding from the lungs. The disease can get serious and become meningitis, which can be fatal.

Some diseases are known to be connected to rats, but not directly transmitted via bite or touch, such as:

  • Bubonic plague – although some studies have suggested it was lice carried by humans, the fact is rats carry parasites which have been shown to transmit the infamous Black Death or Bubonic Plague. This can be fatal if not treated quickly and properly.

  • Colorado tick fever – rats often carry fleas and ticks, and some ticks can then jump species to humans and bite. One of the risks is Colorado tick fever are severe headaches, high fevers, chills, nausea, loss of appetite and can become serious and even fatal.

Because of this risk from rats, it is best to get any rat infestation or problem taken care of quickly. If you have a problem with rats, be sure to contact Ehrlich for help.

Rat risks beyond diseases:

There is also a risk of fires with rats. This is because rats love to chew on wires, such as those between walls in homes. They will chew away the insulation on wires, exposing the wiring beneath, creating a very serious fire risk which can be dangerous.

How fast do rats breed? How many rats are in a litter?

A couple of rats can quickly become a lot of rats and overrun a location very quickly. It has been documented that a female rat can breed as many as 500 times with different mates throughout the course of their life. A female rat can become receptive to mates up to 15 times a year, too.

Rats do not give birth to just one rat at a time, either. They give birth to litters of baby rats and can give birth to litters of 15 pups at a time. Rats also have a very quick gestation period of only 21 to 24 days. So, a single couple of rats can actually produce billions of descendants in a relatively short period of time.

This is why when you see signs of rats, the seriousness of the infestation can be hard to determine. Just a couple of rats can overrun a home or property with more rats and this can lead to dangerous health risks and serious damage to property.

Why do rats smell?

Rats smell so bad because they are dirty. Rats will wander around in sewers, filled with feces, and sit in their own urine and feces, too. Plus, rats scrounge for food anywhere they can find it, such as dumpsters and garbage areas. Rats also do not spend a lot of time cleaning themselves, so they definitely smell bad because they live and walk through dirty, garbage-strewn areas and do not bathe themselves.

What’s the difference between rats and mice?

The difference between rats and mice usually comes down to size. Since rats and mice inside your home tend to hide and move fast, most of the time what you’ll see is a gray streak running past you while looking for a place to hide. However, if the gray streak was big, then it was likely a rat and if you saw a very small gray streak, it was probably a mouse.

Of course, there are other significant differences between rats and mice. Some of them include:

Shape of the body

Mice tend to have smaller, rounder bodies with tiny feet and a small head. They do not weight much, either, usually measuring less than 15 grams.

Rats have thicker, pointier noses and wide, round, fatter bodies. They also have larger hands and feed, weigh more and have large tails that are often pink or fleshy in color and devoid of fur.

Hair and ears

The hair, how much is covers of the body, and the shape of the ears vary from rats to mice. Mice have very large ears compared to the size of their heads and there is some hair on them. Rats have dark hairs on their ears and some have smaller ears compared to their head.

Shape of the nose

Rats tend to have more pointed faces that are longer than those of the mice. There are a few species of rat, such as the Norway Rat, which have more blunted noses. Mice have smaller, pointed noses.


The tails of mice have dark tails and they can also be covered in fur. Most common species of rats have light-colored, hairless tails. Some species of rat have tails that appear dark on top, but pale underneath.


Rats and mice have differently shaped droppings. Norway rats have droppings resembling small capsules, while roof rats have spindle-shaped droppings. Mice tend to leave rod-shaped droppings around.

Nesting spots

Rats are burrowers. One of the most common rats found in homes is the Norway Rat and they prefer to burrow into the ground and will attempt to burrow in places inside the home. Roof rats like attics, to live within walls and also in trees. Mice will hide in various stored materials such as boxes, clothing, inside furniture, within walls, insulation and soft materials they can find and use to build nests.

Rats as pests in homes

How do rats get in your house?

Rats inside a house

Rats are clever and have many ways to get inside your house or building.

First, rats will use any opening they can find to get inside. They can compress their bodies down to incredible size, allowing them to crawl into holes in walls and the spaces between pipes, electrical cables, and other areas. Rats can squeeze beneath front, rear and side doors that do not come down all the way to the floor and will squeeze beneath garage doors without sweeps at the bottom.

The thing about rats is they have very powerful jaws and very strong teeth. Their teeth continually grow, and they have to chew and gnaw on things to keep them under control. These teeth are so strong they can chew through wood and even the siding of houses. Rats have even been known to chew through soft stone and cement. So, if they cannot fit through the opening, they can chew on it and get inside or they can just chew new holes in the outside of homes and buildings to get inside.

Rats are also very good swimmers and can hold their breath, so they can swim their way up pipes and access houses or buildings via toilets in basement bathrooms, for example.

Some species of rats are excellent climbers. Roof rats, for example, got their name for their tendency to climb trees, getting on rooftops and then access attics and upper stories by chewing or prying up roof tiles or shingles and getting inside that way.

What are the signs of rats in the house?

There are numerous signs of rats in your house. These include:

  • Finding droppings – if you find rat droppings in areas around your home, this is a very good sign you might have a rat infestation and need to contact a professional to get rid of them.

  • Smudge marks – down low, against the walls. Rats are dirty and prefer to stay near the walls when they wander around rooms. They will leave dirty smudge marks on the walls when they do this.

  • Noises – these include scratching noises, as rats scurry around the house or between walls, or chewing sounds. Rats need to constantly chew on things to keep their teeth from growing out of control, and will chew on wood and other substances which can sometimes be clearly heard by those in buildings or homes.

  • Rat damage – rats will chew holes in walls, also they will chew up bags containing food or even through plastic containers. If you find chewed wires anywhere, these are also signs of rats. Roof rats will damage roof shingles, too.

  • Nests – you can sometimes spot rat nests if you find piles of insulation, newspaper, and fabric. Rats are good at hiding so these nests might be tucked away in attics, basements or crawl spaces or hidden in the walls.

  • Burrows – rats who have burrowed into lawns or gardens will leave telltale holes in the dirt. There are other rodents such as gophers and moles which will also do this, so if you find suspicious holes in the yard, it is best to call a professional to know for sure.

Of course, you may also be awake at night and see actual rats out and about, scurrying away from you and looking for places to hide.

Why do I have rats in the yard?

Rats are looking for food and shelter. So, if there are things in your yard which they can use for either of those things, they will try to set up their nests and homes in your yard or around your house.

If you have a garden that has vegetables rats can use for food, they may find your yard attractive. If there are piles of wood, vegetation or old lawn mowers, debris, garbage or various things left in the yard they can use for shelter, they might find your yard attractive. If there is a garage or shed, they might also use those for shelter purposes.

Rats prefer to burrow, if possible, so they might burrow in the soft earth of gardens and you may see signs of them, or find the holes and burrows they leave behind. Also, once rats find food and shelter in your yard or garden, they may start to breed and their young might find their way into your home or other buildings and create a full-on infestation.

Why do you get rats in your house? How to get rid of rats in the house?

The reason you get rats in your house is that they find their way in and then find they have easy access to shelter and food. Rats are generally looking for places to build their nests, find easy access to food and to build and raise their young.

Things like:

  • Openings into basements or crawl spaces

  • Openings beneath doors

  • Holes or openings in exterior walls

  • Windows without screens

  • Roof damage and easy access to attics

  • Lawns with debris, clutter or wood

  • Trees or vegetation abutting the side of your home will allow rats to get easy access to the interior walls or interior spaces inside your home.

Once you have rats in your home, it is difficult to get rid of them. Because just a couple of rats hidden in a crawlspace or attic can quickly breed and create a new infestation, once rats have set up their nests inside your home, you will probably need a professional rat specialist to get rid of them.

The best way to get rid of rats in your home is to prevent them from wanting to be there in the first place. Make sure holes in siding, or on the roof, are repaired. Make sure doors have sweeps which are undamaged and go all the way to the ground. Get rid of vegetation, cut back bushes and trees so they are not up against the house. Remove debris and clutter from yards and make sure there is no damage to garages or sheds where rats can hide in backyards, either.

If you have food outside for wildlife or pets, make sure you seal it up as best as possible. Keep garbage sealed up tight and make access to it as difficult as possible for rats. If you have food inside, make sure it is sealed, too, so if a rat does get inside, it will not have access to food.

Do rats have rabies?

For the most part, small rodents like rats and mice are not usually carriers of rabies. They do have the potential to carry a number of other health risks, including those from their bites, but rabies is rarely found within small rodents. Rabies have been found in animals such as raccoons and other larger mammals.

At the same time, there are a number of potentially serious illnesses which can result from rat bites. If you are bitten by any animal, it is best for you to seek medical attention regardless of the potential risks.

Do rats bite?

Yes, rats do and will bite. They generally do not seek out people to bite for no reason and will usually bite only if handled or cornered. Rats also have very powerful and sharp teeth, capable of piercing wood and other substances, and their bites can be painful and carry with them a risk of diseases – some of them serious. No one should attempt to handle a rat that they find in the wild or infesting their home. Doing so poses far too many health risks and if you are bitten, medical attention should be sought.

What happens when a rat bites a person?

Rats have large teeth and a powerful bite, which can be extremely painful for the person bitten. The saliva of a rat contains bacteria and other substances which can cause illnesses such as Hantavirus or leptospirosis.

Rat bites can also cause a reaction known as Rat Bite fever. Most of the time a rat bite will bleed and it can become swollen. However, those with Rat Bite Fever might also get muscle aches, fevers, and severe pain around the bite area. The wound can appear infected with pus and other signs of infection.

If you have any negative reactions to a rate bite, seek medical attention immediately. In fact, it is best to seek medical attention if you are bitten by any animal regardless of initial reactions to the bite.


What do you do when a rat bites you?

Rat bites can be painful and may become infected. There are also numerous health risks involved with rat bites. If you are bitten by a rat or any animal, it is best to seek medical attention and let them know what animal bit you.

You can also wash the wound carefully before you seek medical attention and apply pressure or a bandage to stop any bleeding which may occur.

It is best for you to not try and treat any animal bite on your own, especially given the health risks associated with a rat bite. Seek medical attention quickly.

Of course, if you find you are seeing the signs of rats, or seeing rats themselves, around your home or anywhere on your property, it is best to call in the professionals. Contact your local Ehrlich Pest Control office for help!


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