Rats: What to Know

Common pest rodents that live all over the world, rats can contaminate food, spread diseases to humans and animals, and damage property. Use this guide to help identify rats, their dangers, and what to do if you find them in your home.

What Are Rats? 

Rats are a type of rodent commonly found to inhabit urban areas and are infamously adaptable, making them difficult to get rid of.

Rats can reproduce quickly. Female rats give birth to 3–6 litters of eight or more young each year. Young rats leave their mothers after 3–4 weeks and begin breeding when they are around 3–5 months old. The average rat lifespan is about 1 year.

How Big Do Rats Get?

Different species of rats grow to be different sizes. Norway rats, also called brown rats, are some of the largest pest rats. They can grow between 13 and 18 inches long and weigh between 7 and 10 ounces.

What Do Rats Eat?

Rats are omnivores and will eat just about anything. They enjoy all types of human food, pet food, bird seed, garbage, compost, and even dog feces.

Types of Rats

There are many different species of rats, but Norway rats and roof rats are the most common pests. Both are non-native species that have become problems in the U.S. When attempting to identify rats, note the size, color, and habits of the rats you see.

Norway rats. With brown fur and gray bellies, these rats are larger, stockier, and have shorter tails than roof rats. They average about 13–18 inches long and weigh 7–10 ounces. Norway rats burrow beside building foundations, under garbage and wood piles, and around fields and gardens. Most Norway rats will keep to the basement or first floor when they move indoors.

Roof rats. Also called black rats or ship rats, roof rats have bellies that are gray or white and weigh between 5 and 10 ounces. Their tails are longer than their heads and bodies combined. They often nest in shrubs, trees, and other areas off the ground. Indoors, you can usually find roof rats in cabinets, ceilings, or attics.

Where Do Rats Live? 

Norway rats live in every contiguous state of the U.S., but roof rats prefer warmer climates and can often be found in coastal areas.

Signs You Have Rats 

If you think you might have rats, there are several signs you can look for. Some common signs of a rat infestation include:

• Rat droppings around your home, garage, or pet food dishes 
• Chewed holes around your baseboards or door frames
• Burrows under garbage bins or in your yard, garden, or compost piles
• Rat nests behind boxes or inside sheltered spaces like wood piles or drawers 
• Sounds like something is scratching or moving between the walls or in the attic
• Rats seen around your property or walking along fence tops or utility lines, often around dusk

Are Rats Dangerous?

Rats can be one of the most dangerous pests. Rats spread more disease to humans than almost any other pest — second only to mosquitos.

Do Rats Bite People?

Rat bites are very common. In the U.S., there are over 15,000 reported rat bites each year.

Always take rat bites seriously because rats can carry potentially deadly diseases. Their bites can spread harmful bacteria that cause rat-bite fever. If bitten, use soap and water to wash the wound, and contact your doctor immediately.

Health Risks of Rats

Rats can spread many different diseases to both humans and animals, either directly or indirectly. Direct contact involves:

• Being bitten or scratched
• Eating contaminated food
• Touching contaminated objects or surfaces and then touching your eyes, nose, or mouth
• Breathing contaminated air

Indirect contact with rats usually happens when people or animals are bitten by fleas, mosquitos, ticks, or mites that have bitten infected by rats.

Hantaviruses cause some of the most dangerous diseases you can get from rats. Hantaviruses come in two main types:

• New World hantaviruses. Most common in the Americas, New World hantaviruses can cause hantavirus pulmonary syndrome (HPS). HPS has a 38% mortality rate and causes severe respiratory infections. In the early stages, HPS causes fatigue, fever, and muscle aches in the thighs, hips, back, or shoulders. It can also cause dizziness, headaches, diarrhea, nausea, vomiting, and chills. In later stages, it causes shortness of breath and difficulty breathing as fluid fills the lungs.
• Old World hantaviruses. Most common in Asia and Europe, Old World hantaviruses cause hemorrhagic fever with renal syndrome (HFRS). HFRS is fatal for between 5 and 15% of people infected. Symptoms of HFRS usually begin about 1–2 weeks after infection. Early symptoms include fever, chills, headaches, nausea, stomach aches, back pain, and blurred vision. Some people might get rashes, red or inflamed eyes, and a flushed face. In late stages, HFRS can cause low blood pressure, leaking blood vessels, acute shock, and kidney failure. 

Plague is perhaps the most well-known disease rats spread through indirect contact. Plague is a bacterial disease that killed millions of Europeans in the Middle Ages. In modern times, untreated plague can still cause serious illness or death. Plague can take on three main forms: 

• Bubonic plague. Symptoms include fever, chills, headaches, weakness, and swollen lymph nodes. 
• Septicemic plague. Beginning with similar symptoms as bubonic plague, septicemic plague can progress to cause internal bleeding and parts of the body like the fingers, toes, or nose to turn black and die. 
• Pneumonic plague. In addition to a headache, fever, and weakness, pneumonia quickly develops, causing difficulty breathing, chest pain, coughing, and sometimes watery or bloody mucus.

How to Get Rid of Rats

To get rid of rats, there are several different steps you can take:

• Remove potential habitats. Clear out dense garden beds and shrubs, and keep garbage or wood piles away from your home.
• Prevent access to food. Keep garbage, pet food, bird seed, and other possible food sources in galvanized cans with fitted lids. Remove any uneaten food from the dishes after feeding your pets. 
• Block entry points. Seal any cracks around your foundation, floors, doors, or windows that are wider than one-fourth of an inch.
• Set traps. Rat traps come in a variety of lethal and non-lethal options. If you have Norway rats, put traps in dark areas close to the walls and any place you see droppings. If you have roof rats, place traps along ledges, shelves, beams, and tree branches. 
• Use rat poison. There are many different types of rat poisons available. Carefully follow all safety and usage directions for the product you choose. Rat poisons are toxic to humans, pets, and other animals. Avoid using them indoors, and keep them out of reach of children.