How to Recognize and Control Rats

There are numerous species of rats in the United States, but this article will focus on the rats that cause the most pest problems in homes and businesses. These rats are the Norway rat (Rattus norvegicus) and the Roof rat (Rattus rattus). Furthermore, two other rats, the Rice Rat (Oryzomys palustris) and the Cotton Rat (Sigmodon hispidus), will not be discussed in depth in this article, but are mentioned because they have been identified as hantavirus hosts by the Centers for Disease Control and Prevention and are thus important from a public health standpoint.



Norway rats are also known as brown rats or sewer rats. They are large, bulky-looking rats that can grow to be 13-16 inches long when measured from the tip of their tail to the tip of their nose. The underside of their body is gray, and the top of their body is reddish or grayish-brown to black. The Norway rat’s ears and tail are hairless, and the tail is shorter than the length of the rat’s body. Adult Norway rats weigh 7-18 ounces and have blunt snouts.

Roof rats, also known as black rats, are smaller than Norway rats. Adults weigh between 5 and 10 ounces. Their tails are darker in color and longer than the rest of their bodies. The body of the roof rat is grayish to white on the underside. The roof rat’s muzzle is pointed, and its overall appearance is much more streamlined and sleek than that of a Norway rat.


Behavior, Diet, and Habit



Roof rats are excellent climbers and, as a result, prefer to build their nests above ground. They do, however, occasionally build nests in burrows. These rats prefer to be active at night. The roof rat’s long tail has been observed by scientists to be adapted to enhance their ability to climb and functions to assist them in balancing. Roof rats and Norway rats both have a strong sense of smell and are wary of new things introduced into their home range. Roof rats are not good swimmers and are rarely found in sewers.

Norway rats are usually active at dusk or at night and are dormant during the day. When a Norway rat population becomes so large that competition from other rats for food, water, and shelter becomes too great, some members of the rat community may seek out new areas to colonize during the day. Norway rats build underground burrows in which they mate, rear their young, store food, and seek refuge from predators. Norway rats are strong swimmers and can climb, but not as well as roof rats.



Roof rats are omnivores that eat a variety of vegetation, including fruits, grains, seeds, and grocery produce. Roof rats are also known to eat insects. Roof rats, like Norway rats, destroy far more food than they consume by contaminating it with feces and urine.

Norway rats are also omnivores, meaning they will eat almost anything found near where humans throw away food. Norway rats are also known to prey on fish, poultry, mice, birds, small reptiles, and amphibians. They will consume vegetation but prefer meat or meat-related wastes. Find out more about what rats eat.



Roof rats, as previously stated, prefer aboveground nesting sites in shrubs, trees, and dense vegetation. Roof rats commonly enter homes through raised or secure enclosures such as walls, cabinets, attics, and false ceilings. Roof rats are most likely to be found along the coast, near the coast, and in port cities.

Norway rats prefer to live almost anywhere there are people. Garbage dumps, sewers, and fields are among their natural habitats. Norway rats can be seen scurrying around after dark in most of our cities, looking for food in garbage cans and other places where human waste is found. Burrowing habitats include soil along building foundations, woodpiles, and other debris piles. Norway rats will most likely live in the basement or ground floor of a structure if they infest it. Learn more about the habitats of rats.



Roof rats are polygamous, forming colonies of multiple males and females. Mating can take place all year in areas where the environmental conditions are favorable. Adult females can reproduce at 3-5 months of age and can have up to five litters per year with 5-8 young in each. Adult roof rats typically live for about a year.

Norway rats are polygamous and live-in colonies with many males and females. Mating is most common during the warmer months of the year, but it can occur all year in some areas. Female adults will have approximately seven litters per year and will mate again approximately 18 hours after giving birth to her litter of approximately eight pups. A female Norway rat has a reproductive capacity of 50-60 young per year.


Infestation Symptoms


ATAP Treatment for Rats

The habits, habitats, and behavior of Norway rats and roof rats are very different, so the first requirement of a rat treatment program is to correctly identify the rat and develop a treatment plan that works for that species. Customer education is another important treatment component that ensures the customer understands the concepts of the proposed control program.

ATAP pest management professionals (PMPs) use all rodent Integrated Pest Management techniques. Rats are treated using both non-chemical and chemical methods. The following are some of the more important non-chemical methods:


Baits designed to kill rats are used in chemical rat control. Care must be taken to ensure that baits are properly placed and that the product’s labeled instructions are strictly followed. One of the most common baiting techniques is to place the bait formulation in a tamper-proof rodent bait station, which protects the bait from accidental exposure to non-target animals or people. Fumigation of transport vehicles or rat ground burrows may be required in situations where rats cannot be controlled with conventional products.


Contact our trained ATAP pest control professionals at (708) 980-0092 for more information on rats and how to prevent or eliminate infestations in your home!

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