Whether you’ve just discovered droppings, gnaw marks on your furniture, or, worst of all, a live animal, you know there’s a rodent in your home. But is it a rat or a mouse?
Telling the two species apart can be tough to the untrained eye, but with a bit of investigation, you can figure out the differences—especially in their size, tails, and droppings. Here’s how to determine whether you’re dealing with mice versus rats, plus how to keep them out of your home, according to pest control experts.
First, are rats and mice different?
Yes, mice and rats are two different kinds of animals. “A mouse and a rat are as different as a housecat and a mountain lion,” says Bobby Corrigan, Ph.D., an urban rodentologist based in New York City. “Rats and mice are both rodents, but completely different species.”
How can you tell rats and mice apart?
Telling a mouse from a rat is actually pretty easy, especially if you get a good look at one. Size is the most obvious difference, explains Ian Williams, board-certified entomologist and technical services manager at Rollins, Inc. in Atlanta. Mice have bodies that are three to four inches long, with tails two to four inches long; rats, meanwhile, have bodies that are five to 10 inches long, with tails five to nine inches long.
“A rat, relatively speaking, is a pretty big rodent,” Corrigan says, weighing about a pound to a pound and a half. But mice are tiny, clocking in at around half an ounce. “Everybody gets caught by the presence of a rat,” he explains, but mice are easier to miss—and some might even call them cute.
Their tails are also quite different, since rats have longer, thicker ones and mice have daintier, thinner ones. Yet another difference is their droppings; much like the rodents themselves, rat droppings are larger and thicker than mice droppings.
Are there different species of rats and mice?
Although there are hundreds of species of rats, there are two main types that homeowners typically encounter in the United States, Williams says: the Norway rat (a.k.a. the brown rat) and the roof rat (a.k.a. the black rat). If you have a mouse in your home, it’s likely the (aptly named) house mouse. In some regions of the country, Williams notes, you might also encounter the deer mouse and the white-footed mouse, but they are less common.
Do baby rats and adult mice look the same?
Baby rats look quite different from adult mice. “A baby rat will still be twice as big as a mouse,” Corrigan explains. Another key difference: Baby rats have giant heads, he notes, like “someone blew it up with air.” Their hind feet will also be too big for their body, much like puppies, Williams says.
Mice, meanwhile, have normal-looking heads and feet—a dead giveaway that you’re dealing with the smaller pest. And no, mice can’t grow into rats; they’re completely separate animals. In fact, the two species can’t even cross-breed, Corrigan says.
Are rats worse than mice?
“A rat can potentially do more damage more quickly simply because it is larger than a mouse,” Williams says, but “both have a tremendous capacity for reproduction, and both come with their share of diseases.”
“They’re both unwanted guests around homes,” Corrigan explains, and they can chew at furniture and wires, contaminate your food and surfaces, and colonize your living spaces. It’s worth getting both mice and rats out of your home as soon as possible.
How do you prevent rats and mice?
It’s simple to keep rodents at bay, according to Corrigan. When you put out your garbage, make sure it’s sealed tightly in a bag and inside your bin. And every once in a while, spritz your garbage can with a 10% bleach solution, which throws pests off of the scent. Otherwise, your bin is akin to a bird feeder; much like how birds find seeds you leave out for them, rodents will find food scraps you throw away improperly, inviting them to check out your home, too.
“Prevention is key,” Williams explains: Move wood piles away from your home, clear dense vegetation from your home’s foundation, and eliminate any food and water sources in your yard. (Interestingly enough, actual bird feeders also attract mice and rats, so you should consider putting out suet instead, Williams says.)
You should also do a perimeter check, making sure that all doors close securely. Take a #2 pencil with you; if you can fit one below a door, mice and rats can get inside with very little effort, Corrigan explains. Seal gaps of the same size in your foundation and around your roof, Williams advises.
And if you’re dealing with an infestation, don’t go it alone—both experts stress that it’s best to reach out to a pest management professional, who has the know-how to keep rats and mice out of your home.
Jake Smith
Jake Smith, an editorial fellow at Prevention, recently graduated from Syracuse University with a degree in magazine journalism and just started going to the gym. Let's be honest—he's probably scrolling through Twitter right now.
