Rats vs mice: how to tell which one you have

How do you tell a rat from a mouse?

Size first, then the shape of the head and tail.

The house mouse and Norway rat measurements are the ones on our rodents page. A young rat can be mouse-sized, but its head and feet look too big for its body; a grown mouse never does.

What about field mice and deer mice?

"Field mouse" usually means a deer mouse or a close relative — native mice of fields and woods rather than the house mouse. A deer mouse has a grayish- to reddish-brown back, a clean white belly and large dark eyes, and its tail is two-toned: dark on top, white underneath.

Deer mice live outdoors most of the year, then move into homes, garages, sheds and cabins in late fall and early winter. A mouse with a white belly in a garage or outbuilding is usually a deer mouse; a plain gray-brown one in the kitchen is usually a house mouse.

What do mouse and rat droppings look like?

They are the easiest way to tell the two apart without ever seeing the animal.

Mouse droppings are small, dark and rod-shaped with pointed ends — about the size of a grain of rice. Mice leave them scattered wherever they travel, especially along walls, in drawers and cabinets, and under sinks and appliances.

Rat droppings are much larger — about 3/4 inch, the size of a raisin or an olive pit — with blunt ends, and they tend to be found in groups along the routes rats use.

Fresh droppings are dark and soft; old ones are dry, gray and crumble. Which kind you find tells you where they are active now, not just where they once were. Wear gloves and avoid sweeping droppings dry, which stirs up dust; clean them up damp.

Where do mice and rats nest?

Differently, which is why the difference matters.

Mice nest inside. A house mouse will live its whole life in a wall void, a cabinet base, behind a refrigerator or in attic insulation, a few feet from its food. It needs very little water and very little space.

Rats usually nest outside and come in. Norway rats dig burrows along foundations, under slabs, sheds and woodpiles, and beside garbage, and come indoors for food — more often in cold weather, when they sometimes move into walls, crawlspaces and attics.

So mice are usually an inside problem with an entry point, and rats are usually an outside problem that has found a way in.

How do mice and rats get into a house?

Through gaps far smaller than they look. A mouse can squeeze through an opening about 1/4 inch across — roughly the width of a pencil. A rat needs an opening about the size of a quarter. Both use gaps around pipes, vents, dryer lines, garage doors and the foundation, and both can climb.

That is why sealing matters more than anything else: a house with the gaps closed stays closed, and a house with them open keeps filling back up.

Why do traps work on mice but get ignored by rats?

Because they behave differently around anything new.

Mice are curious. They investigate new objects in their territory quickly, which is why a trap set along a wall often catches one the first night.

Rats are cautious of new things. A rat will often avoid a new trap or bait station for days before it treats it as part of the furniture. A trap sitting untouched does not always mean there are no rats — sometimes it means they have not accepted it yet.

Are rats nocturnal?

Mostly. Rats and mice are most active from dusk through the night, which is why scratching in the walls or ceiling usually starts after the house goes quiet. A rat seen in daylight often means a large population, a disturbed nest or a shortage of food, and is worth taking seriously.

How do you get rid of rats?

Take away what they came for, then close the door behind them:

• Food: pet food, bird seed, garbage and fallen fruit, stored in sealed containers and cleaned up at night.
• Shelter: woodpiles, clutter and dense plants against the foundation, where rats burrow and hide.
• Entry: gaps about the size of a quarter around pipes, vents, garage doors and the foundation, sealed with metal or concrete that rats cannot chew.
• Trapping along the walls and runs they use, allowing for their caution around new objects.

Because rats usually live outside and come in, the outside work — burrows, harborage and entry points — matters more than anything done inside.

What is the difference between squirrel droppings and rat droppings?

Size and shape overlap, so where they are found helps. Rat droppings are about 3/4 inch with blunt ends and are often found along walls, in groups on the routes rats use. Squirrel droppings are similar in size but more oval and rounded, often lighter brown, and tend to be scattered in attics near the entry hole, usually along with chewed wood and nesting material. Squirrels are active by day and rats by night, so daytime noise in the attic points to squirrels — see squirrels in the attic.

What are the signs of mice or rats in the house?

• Droppings along walls, in cabinets and drawers, and under sinks
• Gnaw marks on food packages, wood, wiring and plastic
• Scratching or scurrying in walls, ceilings or the attic at night
• Nests of shredded paper, insulation or fabric in hidden spots
• Greasy rub marks along walls and beams where rodents travel the same path
• Burrows along the foundation, under slabs or beside sheds — a rat sign

How does Liberty handle mice and rats?

Both are covered. Rodents are covered by every Liberty pest control plan, and all rodent problems start with a free inspection.

All rodent problems start with a free inspection with a local Service Advisor. On your first visit, your Service Specialist does a thorough inspection inside and outside to see how bad the problem is, where mice and rats get in and what draws them, like food, water, clutter and nesting spots.

• Seal entry points: Your Service Specialist finds and seals the gaps mice and rats use to get in, like openings around pipes, vents and the foundation.
• Bait stations: They place tamper-resistant bait stations where rodents travel, like along the foundation and walls.
• Traps indoors: They set traps where mice and rats are active inside, like attics, crawlspaces and behind appliances.

More on the fall move indoors is in our mice in the house article.

When to call a professional

Call when you find fresh droppings, hear scratching in the walls or ceiling at night, or see burrows along the foundation. Call as well when the problem keeps coming back after trapping, which usually means the way in has not been found.

The inspection settles whether it is mice or rats and where they are getting in; the sealing and the rest of the work follow from that.

Common questions

How can you tell a rat from a mouse?

By size and shape. A house mouse is about 5 1/2 to 7 inches long counting its tail, with big ears and a pointed nose. A Norway rat is about 12 to 18 inches long, heavier, with a blunt nose, small ears and a thick tail.

What do mouse droppings look like?

Small, dark and rod-shaped with pointed ends, about the size of a grain of rice, scattered along walls, in drawers and cabinets and under appliances.

What is the difference between rat droppings and mouse droppings?

Size and shape. Rat droppings are about 3/4 inch long with blunt ends, about the size of a raisin; mouse droppings are about 1/8 to 1/4 inch with pointed ends.

What is a field mouse?

Usually a deer mouse: a native mouse with a brown back, white belly, large eyes and a two-toned tail. It lives outdoors much of the year and moves into homes, garages and sheds in late fall.

How small a hole can a mouse get through?

About 1/4 inch — roughly the width of a pencil. A rat needs an opening about the size of a quarter.

How do you get rid of rats?

Remove their food and shelter around the house, seal gaps about the size of a quarter with material they cannot chew, and trap along the routes they use. Most rats live outside, so the outside work matters most.

Are mice and rats covered by a Liberty pest control plan?

Yes. Rodents are covered by every Liberty pest control plan, and all rodent problems start with a free inspection.

Sources

1. University of Kentucky Entomology. Michael F. Potter. "Control of Mice" (ENTFACT-617). https://entomology.mgcafe.uky.edu/ef617 ↗ (opens in a new tab)
2. University of Kentucky Entomology. Michael F. Potter. "How to Pest-Proof Your Home" (ENTFACT-641). https://entomology.mgcafe.uky.edu/ef641 ↗ (opens in a new tab)