Brown Rats

Brown Rat Control: Protect Your Home


Scientific Classification: Rattus norvegicus, Berkenhout



Also known as Norway rats, sewer rats, or wharf rats, brown rats are the most prevalent species of pest rat found in the United States. The common rodents typically live in populated areas, where their destructive habits often cause problems for humans. Brown rats are known to contaminate food supplies, damage property, and spread diseases.


What Do They Look Like?

Size: Larger and stockier than other rat species, adult brown rats generally range from 12 to 18 inches in length and weigh between 12 and 16 ounces. The body length includes the tail, which typically measures about six to eight inches long by itself.

Color: Brown rats, as the name of the species indicates, are brownish in color. The primarily brown fur turns paler and grayish on the underside of the rodent.

Characteristics: In contrast to other common pest species of rats, the scaly tail of the brown rat is shorter than the length of the body. Other distinguishing characteristics of brown rats include coarse fur, small ears, and a blunt nose. Inherently wary of new or unfamiliar objects, brown rats are most active at night and rely on their highly developed senses of hearing, smell, and taste.

Geographic Range

Found in all 50 states, brown rats tend to live most commonly in populated areas rather than sparsely settled regions.


What Do They Eat?

Brown rats demonstrate a strong preference for sources of protein, such as fish, insects, meat, and pet food. The pest rodents also like to eat fresh grain and require at least 1/2 an ounce of water each day.


Naturally social, brown rats live in colonies that operate according to an established pecking order. Breeding, which may occur at any point throughout the year, usually takes place most frequently during the warmer seasons. After mating occurs, the female brown rat undergoes a three-week gestation period before giving birth to a litter of four to eight pups. Newborn brown rats achieve sexual maturity about 3 months after birth and may live as long as 18 months, though most die within a year. On average, females produce about five litters each year.


  • Brown rats usually reside on the lower levels of buildings and often establish colonies within walls or cluttered storage spaces.
  • Listen for telltale sounds like squeaking, gnawing, scrambling, and rustling noises.
  • Look for tracks, droppings, and urine stains. Rat urine produces a blue-white glow when exposed to the ultraviolet (UV) rays of a black light.
  • Extremely infested areas emit a particular odor, which helps distinguish the presence of brown rats from an infestation of mice.

Problems Caused by Brown Rats

Due in large part to their adaptability, brown rats frequently live in close proximity to humans and may cause various problems as a result. The foraging pests often crawl through sewers and similarly contaminated areas before entering homes and coming into contact with food and kitchen surfaces. Brown rats may also contaminate food directly by urinating or defecating. The unsanitary rodents carry bacteria known to cause food poisoning, leptospirosis, trichinosis, and other illnesses. In addition to bacteria, brown rats often carry fleas and mites with the potential to spread plague and typhus fever.

Signs of Infestation

Despite nesting in generally concealed areas, brown rats consistently leave behind evidence signaling infestation problems. Telltale signs of a brown rat infestation include the squeaking and gnawing sounds the rodents make, the discarded droppings the pests produce, and the 3/4-inch long footprints the adults leave. Brown rats also create noticeable runways by repeatedly traveling the same path to forage for food. Sometimes, established runways feature smudge marks that appear as a result of the grease and oils rubbed off from the fur of the rodents. Gnawed holes represent another sign of infestation, as brown rats chew on hard materials constantly.

Prevention Tips

Preventing a brown rat infestation largely comes down to proper sanitation and the elimination of potential entry points around the home. Proper sanitation entails cleaning spills promptly, storing food in sealed containers, and removing trash before it has time to accumulate, while eliminating potential entry points involves sealing cracks or holes, plugging the openings around utility pipes, installing metal grates over floor drains, and making sure window screens fit tightly. Other preventative measures include trimming or removing bushes, hedges, tall grass, and weeds to reduce the amount of ground cover that foraging rats can exploit.

Tips for Removal from Home

Removing a brown rat infestation from the home often involves the use of traps and baits, or a combination of both. However, most options for controlling rats require a level of knowledge and patience that many homeowners find daunting. Certain baits, for instance, only work as long as the rats have access to a continuous supply over the course of several days or even weeks. Furthermore, failing to follow due diligence not only diminishes the effectiveness of these materials but may also expose children, pets, or other non-targets to these control materials. For best results in handling a severe brown rat infestation and implementing a plan to prevent future problems, contact a professional pest control service.

History of the Brown Rat

Where there’s one, there’s probably more. At least when it comes to rats. And that has been the case for millions of years. They fight for food, they fight to play, and they fight to survive. Let’s find out more about rats from past to present.

Rodent Identity Crisis

Rat, fahr fara (Arabic), chuot (Vietnamese), tikus (Indonesian), jwee (Korean). The common rat has many names. But do you know where they actually originated? Don’t be misled by the nickname, “Norway rat.” It’s believed that the first rats lived in Asia, descending from ancestors that went by the name of “anagalids,” which also spurned Lagomorpha (also known as rabbits). Rats came to be about 34 million years ago during the Eocene period. The Murid family of rats transitioned into the Rattus genus and spread to Mediterranean countries, the Middle East, and Australia. Eventually, rats started to creep into Europe (displacing black rats), and then into our turf, the U.S.

Rats of Many Names, and Also Many Homes

The house rat, the sewer rat, and the wharf rat… do you know why the common brown rat is known by all three names? Those are the places rats started to find homes. In Europe during the 18th and 19th centuries, people actually ate rats during famines. Rats were also used for entertainment – rat fights, rat pits, and rat courses often served as diversions. It was also in the 1800’s that the use of lab rats began for medical testing. Some people started to keep rats for pets as well.

In the olden days, rats ate almost anything…today, they’re still inclined to sink their teeth into unusual objects like computer cords, pipes, bed posts, floors, dog food, crown molding, soap, and candy. But generally, they munch on meat, fish, and livestock grain (anything softer than their own teeth); rats can fill themselves up with almost 1/3 of their body weight. They’re not messin’ around when it comes to snack time! Not only do rats have a keen sense of taste, they are also very sensitive listeners, and have a strong sense of smell. (These strong senses easily direct them to their meals.)

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