Norway Rats: When Do They Become a Problem?

Norway rats, also known as brown rats or sewer rats, are an invasive species of rat commonly found in neighborhoods and residentials areas. Norway rats are highly destructive and potentially deadly, as they contaminate food, damage buildings, and spread disease. Although these rats are dangerous pests, they look relatively innocuous, measuring anywhere between thirteen to eighteen inches long (including the tail) with coarse brown fur, white underbellies, and small ears. 

Norway rats are not specific to any particular region of the United States, although they seem to be especially fond of damp areas that are close to a source of water. They have incredibly sharp hearing and a keen sense of smell, which allow them to locate food and shelter while avoiding predators. Like most rats, they are nocturnal, preferring to forage for food between dusk and dawn. Once they have settled in, Norway rats will breed year round, resulting in litters of six to twelve babies every month—that’s a lot of rats!

Why is the Norway rat a problem?

Norway rats tend to be a major problem in many neighborhoods, as their propensity to gnaw through most materials can gradually destroy buildings, power lines, electrical wiring, and much more. They can even chew through plastic and lead pipes if they’re tempted by the prospect of food or water. If they crawl between the walls of your home, they may gnaw on the wiring, resulting in frayed wires and greatly increasing the risk of a fire. 

Norway rats may pose an even greater threat to your health—they are known carriers of fleas and potentially life-threatening diseases. In their search for food, water, and warmth, they can often chew themselves into your food and water supplies, contaminating them with urine and feces that may carry potentially fatal diseases such as jaundice, rat bite fever, trichinosis, and salmonellosis. Norway rats can also carry fleas that, once introduced into your home, can infect you or your pets with various diseases. 

How do I prevent a Norway rat infestation?

As with most pests, preventing an infestation is better than trying to handle one that has already occurred. It’s important to be proactive and take steps to keep Norway rats out of your home and neighborhood. Always make sure to seal any potential food and water sources, including garbage cans (make sure the lid is shut securely and that it does not overflow with trash), bird feeders (get bird feeders that hang in the air and can be sealed shut), and pet food (store it in a sealed, airtight container). Cut off their water sources by making sure to fix any leaking pipes, regularly emptying and cleaning out any outdoor container that holds water (birdbaths, watering cans, inflatable pools, etc.), and ensuring that hoses and sprinklers are not dripping water. Check your basements and crawl spaces to make sure that there are no damp spots that may invite Norway rats. 

Additionally, make sure that there are no convenient gaps or crevices through which the rats can enter your home. Once the rats are inside, it’s extremely difficult to determine their number and location, so it’s important to make sure that they don’t get a chance to enter. Use cement or steel wool to plug any holes or gaps on the exterior of your house, and don’t leave windows or doors open, especially during the nighttime, when they are at their most active. Norway rats are particularly attracted to piles of wood, in which they like to nest—make sure your pile of firewood doesn’t become a rat sanctuary by storing it in a sealed structure apart from the house.

How do I know if I have a Norway rat problem?

If you suspect that Norway rats have already infiltrated your house, there are several telltale signs that can help you decide whether it’s time to contact a pest control specialist. Look for rodent droppings around your house; they generally tend to be small dark pellets between three to five millimeters long, and usually left in places where food is stored. Do regular checks of kitchen cabinets, cupboards, and food storage containers to make sure that there are no droppings. 

If you hear strange scratching noises coming from inside the walls of your house in the middle of the night, don’t panic! It’s most likely a family of rats scurrying around inside the walls. Encountering rat nests or gnaw marks is also a clear sign of a rat infestation. Norway rat nests tend to be located in warm, dark corners and made of soft materials such as cotton, paper and clothing scraps, and wall insulation. And finally, if you spot an actual rat in your house, that’s a pretty solid clue. Norway rats breed very quickly, so if you have one rat in the house, there’s a good chance that there are several others hidden elsewhere. 

How do I get rid of Norway rats?

If you do have a Norway rat infestation, there are several simple steps you can take to eradicate them. Rat traps are a classic and effective method that can be found at most hardware stores. However, they are not entirely foolproof, as it only takes a couple of cautious rats to elude the traps and repopulate. Rat poison is another very common method of pest control, but this method requires extreme caution to prevent children, pets, and other animals from ingesting the poison. 

Ultimately, the safest and most effective way to combat your Norwegian rat problem is to contact a pest control company—these companies are specially equipped to handle pests without compromising your safety, and it’s always better to be safe than sorry. If you suspect that you have an infestation, don’t hesitate to call the experts.