Rat Control: How to Get Rid of Rats

Rats (Rattus: Rodentia)

Rats are typically distinguished from mice by their size; rats are generally large rodents, while mice are generally small rodents. Two types of rats can be found in Washington, the Norway rat and the roof rat. Both were unintentionally introduced into North America by settlers who arrived on ships from Europe. The Norway rat is also called the brown rat, dump rat, barn rat, sewer rat, gray rat, or wharf rat.  The roof rat is somewhat smaller than the Norway rat and is a more agile climber.

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General Facts/Information of Rats

The Norway rat is now spread throughout the United States. It is generally found at lower elevations, but may occur wherever humans live. The roof rat, however, tends to live more along the coastal areas throughout the United States. Most roof rats in Washington occur in the western part of the state. Few reported incidences of roof rats have been made in the central basin or eastern part of the state.

Rat Prevention and Control

Habitat. Rats live in close association with people. Depending on the species, they burrow or climb to make nests in buildings and structures, beneath concrete slabs, along streambanks, in trees around ponds and garbage dumps, and other locations where suitable water, food, and shelter are present.

On farms, they may inhabit barns, granaries, livestock buildings and kennels. In urban or suburban areas, they live in and around residences and cellars, warehouses, stores, slaughter houses, and sewers. Although they can climb, Norway rats tend to inhabit the lower floors of multi-story buildings.

Roof rats are more aerial than Norway rats in habitat selection. They often live in trees, attics, walls, beams, or vine-covered fences. Landscaped residential or industrial areas provide good habitat as does vegetation on river banks and streams. Roof rats are sometimes found living in or around poultry or other farm buildings as well as industrial sites where food shelter are available.

Roof rats frequently enter buildings from the roof or from access near utility lines which they use to travel from area to area. They are often found living in second floor of a warehouse, whereas Norway rats sometimes occupy the first floor and occasionally live in sewer systems.

Breeding seasons vary in different areas. Usually, peak breeding occurs in the spring and fall. Norway rats prefer a nest underground, while the roof rats prefers a nest in locations off the ground and rarely digs burrows for living quarters.

Feeding Behavior. Rats will eat nearly any type of food. When given a choice, they select a nutritionally balanced diet, choosing fresh, wholesome items over stale or contaminated foods. Norway rats prefer meats and fish, while roof rats prefer cereals, grains, nuts, and fruits. Rats require 1/2 to 1 ounce of water daily when feeding on dry food, but need less when moist food are available. Food items in household garbage offer a fairly balanced diet  and also satisfy their moisture needs.

Rats usually begin searching for food shortly after sunset. Many rats will hoard considerable amounts of solid food, which they may or may not eat later. Rats as well as other rodents are sometimes observed gnawing on wood. This behavior stems not from nutritional need but rather is an attempt to keep their teeth worn down.

Damage. In warehouses, they gnaw into materials, especially stored or packaged foods. They often live in attics or in the spaces between floors. They may gnaw on electrical wires and tear up insulation for nesting. In backyards, they often live in overgrown landscaped areas, feeding on ornamentals, vegetation, fruits, and nuts. In some situations pet foods, bird seed, and garbage may be major food sources.

Rodent-Borne Diseases

Rats and mice spread a number of diseases; directly, by contamination of human food with their urine or feces, or indirectly, by rodent fleas and mites.

Hantavirus Pulmonary Syndrome (HPS): Causes a form of adult respiratory disease syndrome which can be fatal (45%). HPS is spread by infected deer mice through their urine, saliva, feces, and nesting materials. Human infection may occur when people breather air contaminated by deer mouse droppings and urine or objects they have touched, eaten, or lived in.

The virus can become airborne when a nest is disturbed or when someone sweeps up dry droppings. Avoid all wild rodents. Deer mice (main carrier) can carry and shed the virus without appearing sick. They live primarily in rural areas, and exposure may occur in homes, outbuildings, or outdoors.

Rat-Bite Fever: The bacteria that cause rat-bite fever are found on the teeth and gums of many rats and are transferred from rat to humans by the bite of the rat. The most frequently occurring rat-bite fever in the United States is called Haverhill fever. It is similar to the rat-bit fever of the Orient called sodoku.

Leptospirosis: Human cases of the disease results from direct or indirect contact with the infected urine of the rodents and of certain other animals. The spirochetes, which are found in water or on food, may enter through mucous membranes or minute cuts or abrasions of the skin.

Salmonellosis: Generally classed as food poisoning, Salmonella is a common disease of world-wide distribution. Bacteria are spread in various ways, one being through food contaminated with rat or mouse feces containing Salmonella organisms.

Trichinosis: Humans, hogs, and rodents may develop the disease from eating infected pork that is raw or insufficiently cooked. In addition, research has shown to indicate that rodents may play an important role in spreading trichinosis to hogs fed on garbage containing infected rat feces.

Plague: Plague is the "Black Death" that once killed millions of people in Europe, Asia, and Africa. No serious outbreaks of plague have occurred in the United States since 1924. However, a reservoir of the disease exists in wild rodents of the western states, where the bacteria are transmitted from one rodent to another and sometimes to humans by the bite of rodent fleas. It is important to note, Fleas carrying the plague organisms have been taken from trapped rats in Tacoma as recently as the mid-1970s.

Pest Fighter pest control company is a professional, licensed and insured pest control operator (PCO) located in the Greater Seattle area, serving King County, Pierce County and Snohomish County. Pest Fighter not only prevents pest problems, but we offer an Integrated Pest Management (IPM) solution for both treating pest problems and monitoring for the presence of pests and pest damage. For help in controlling rats in your area of Washington, contact your local Pest Fighter or pest control operator (or PCO).