Just How Destructive Are Rats?


The sighting of a single rat dropping sends some homeowners into a panic. They buy a rat zapper, set out poison, order ultrasonic rat deterrents, and then call the exterminator just to make sure they get rid of their rats for good. Other homeowners simply sweep the signs of rat infestation away (one hopes, not under the rug) and allow rodents to multiply, without realizing just how much damage rats can do.

How destructive are rats? Here are ten ways rats can cause damage to your home, to your pocketbook, and to your health, in addition to creating an unsightly mess.

1. Rats have to feed 15 to 25 times per day and consume 10 to 15% of their body weight in food daily.

By the time a brown rat has lived to the ripe old age of two years, it will have eaten as much as 50 kilos (over 100 pounds) of food. But because rats have discerning palates, a single rat may ruin 10 times as much food as it eats, or even more.

Black rats tend to specialize in finding their favorite foods. Brown rats will eat any and all kinds of food, but they only eat the freshest and most flavorful food. Because a rat holds food between its paws as it eats, the ends of food are left on the floor. And because rats mark their territory with urine, an entire container of food is ruined when a rat has eaten only a small part.

2. Rats love to gnaw through electrical insulation to keep their teeth sharp.

One evening, Robert took his cat to the vet for an overnight stay. The next morning, he couldn’t start his car, because a rat had gnawed through just a single wire in the harness in the hood of the vehicle. Repairing that wire took just a drop of solder and about two minutes, but finding that wire involved a US $1200 mechanic’s bill.

Rats also chomp down on insulation inside houses and flats. House fires are not impossible, and mysterious electrical outages requiring repairs by the electrician can cost enormous amounts of money.

3. Rats love to gnaw through thermal insulation.

Rats also love to cut their teeth on thermal insulation in attics and crawlspaces. The unravelling of tightly packed insulation admits hot air during the summer and cold air during the winter. An ongoing rat infestation around the water heater may not only increase the cost of heating but also increase the risk of fire.

4. Rats don’t come toilet trained.

A rat may defecate as often as 60 times a day. Rat droppings not only stink, but they also attract other rodents and can harbor disease. The most common infections transmitted to people by rat dropping picked up with bare hands are Salmonella and tapeworms. In the American southwest, rats sometimes transmit a potentially deadly hemorrhagic fever known as hantavirus.

5. Rats endanger pets.

Locking a cat into an enclosed space inhabited by a pack of rats means an almost certain death for the cat. Rats will attack predators many times their size when the rats outnumber their enemies. Rats also like to feed on kibble and bits that are the perfect size to be held in their paws, spreading microorganisms that cause diarrhea and intestinal parasites to cats and dogs.

6. Rats damage roofing.

A leak in the roof on a rainy day can quickly cause enormous damage. Black rats are especially fond of chewing on the eaves of roofs in ways that let rain and other rodents inside.

7. Rats have caused a resurgence of an infectious disease known as leptospirosis.

Leptospirosis is an infection humans usually acquire by handling the urine of dogs or cats that have been infected by rats, or by cleaning up rat infestations. This infection is caused by a tentacled bacterium known as a spirochete. The spirochetes have the ability to change their shape and to thicken cell walls to resist drug treatment (you can read more about it at Medscape). Sometimes leptospirosis results in just a few days of fever and joint pain, but sometimes it results in death due to multiple organ failure. Getting rid of rodents including both rats and squirrels inside the home is essential to protecting humans and pets from this disease.

8. Rats can also ruin your lawn and garden.

Rats eat bulbs and seedlings, especially in late summer. The rats you drive out of your house or flat may feast on your flowerbeds.

9. Norway rats may damage the foundation of your home.

Imagine not waking up one morning and not being able to go out your front door because the foundation of your house has shifted. Burrowing rats can undermine foundations in ways that cause doors, windows, and interior walls, as well as gas and water pipes, to shift.

10. Rat infestations can become a source of personal financial ruin.

In the United States, rats cause between $500 million and $1 billion of damage to homes each year. Some individual homeowners, however, have suffered as much as $1 million in personal losses from rat infestations, usually when the builder made an improperly placed connection to the sewer system.

Don’t let rats ruin your home or your health, or endanger your children and your pets. Find out how to get rid of rats, the right rat traps to use and right rodent deterrent systems now.


Mark has a strong background in Engineering and a huge interest in Pest Control as a way of getting rid of rodents and other unwanted pests who can cause a nuisance in your home and garden. You can subscribe to his free daily paper on Pest Control Solutions and follow him on Facebook or Twitter

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  • Just want to say thank you. Excellent info. You helped me figure out that I have Norway rats. I had many borrows throughout my yard for years. I was shure they were not gophers. (no dirt mound piles at any of the holes.) I would flush some of the holes in the back yard and I would be able to flush the hole and be able to keep inserting the garden hose at least 5 to 6 feet at a time. No critter ever came out and I never seen evidence where the water went or came out. If this was a gopher, it would have come out by then,as I have done this many times at my sisters house and have gotten the gopher. I was digging around my house foundation and discovered tunnels running along the concrete at horizontal 8 to 10 inches deep. Some tunnels would veer off and go deeper. I wouldlike to eliminate them before a problrm developes with my foundation. Your article was the only one that clued me in about Norway rats creating foundation problems. Now I just need to decide which baite to use for Norway rats. I for sure want to bait around my house foundation. THANK YOU

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