The Norway Rat is the Brown Rat, Gray Rat, Common Rat, House Rat, Wharf Rat, Sewer Rat, Barn Rat, and Water Rat. Though not actually from Norway, this rat was first identified there. They are found all over the U.S. Norway rats are the most likely type to get into homes and buildings and are a much bigger problem to eliminate once they do.

Norway rats have course fur and are often completely black. They can also be grayish brown, but the color may vary from a pure gray to a blackish or even reddish brown. The belly is usually gray to yellowish white. The body is heavy and thick, weighing anywhere from 12 - 24 ounces. They are approximately 7 - 10 inches long. The tail is shorter that the length of the head and body at about only 6 - 8.5 inches. The tail is dark on top and lighter on the underside.

Norway rats can gnaw through wood, lead, aluminum, copper, even cinder blocks and uncured concrete. They burrow into the soil and are excellent swimmers and climbers. This rat will usually nest in basements or lower portions of buildings, wall voids, underneath floors or in stored materials. Norway rats are nocturnal, feeding half hour after sunset and half hour before sunrise. They have a strong social hierarchy.

They are omnivores and can eat about anything they prefer, including meat, fish, flour, cereal, gains, fruits and vegetables, anything left over by humans, even grease. A water source is essential.

These rats become sexually active at about 5 weeks of age. The female creates a nest in a secluded place of a home or building, or may burrow or tunnel outside. They can have up to 7 litters each year. On average an adult rat lives 9 - 24 months.

The Roof Rat, also known as the Alexandrian Rat, Black Rat, Fruit Rat, and Ship Rat. Their usual territory covers from 100 to 300 feet. They frequent the same runway daily. Most of their activity is at night.

The Roof Rat has a slender body, and is 6.5 to 8 inches long, weighing about 6-12 ounces. The color varies from black to brownish gray with a white to gray belly. This rat has a hairless tail and its tail is longer than its head and body length at 7.5 - 10 inches. Just the opposite of the Norway Rat, but the Roof Rat is distinguished by its large ears and more pointed nose.

They will nest in trees or thick ground cover and in the upper floors of homes and buildings. They are omnivores eating snails, fruits, grains, vegetables, nuts and seeds, along with pet food and just about anything left over by humans. A water source is essential for this rat as well.

The Roof Rat reaches sexual maturity in 3 months. They are in heat every 4 - 5 days. Gestation is 21 - 23 days, resulting in a litter of 5-8 pups. After giving birth the female is capable of being in heat again in just 24 - 48 hours. Many generations can be produced each year.

The house mouse (Mus musculus) is considered one of the most troublesome and economically important pests in the United States. House mice live and thrive under a variety of conditions in and around homes and farms. House mice consume food meant for humans or pets. They contaminate food-preparation surfaces with their feces, which can contain the bacterium that causes food poisoning (salmonellosis). Their constant gnawing causes damage to structures and property.

Droppings, fresh gnawing and tracks indicate areas where mice are active. Mouse nests, made from fine shredded paper or other fibrous material, are often found in sheltered locations. House mice have a characteristic musky odor that identifies their presence. Mice are occasionally seen during daylight hours.