The fastest way to tell: look at the droppings. Rat droppings are large — about the size of a raisin (0.5 to 0.75 inches). Mouse droppings are tiny, like a grain of rice. You can also compare body size, tail length, ear size, and behavior patterns. Knowing which you have matters because control strategies differ significantly.

Side-by-Side Comparison: Rats vs. Mice

Here’s how to tell them apart:

  • Droppings — This is usually the clearest sign. Rat droppings are large, dark, and capsule-shaped (Norway rat: blunt ends; roof rat: pointed ends). Mouse droppings are tiny, granular, and pointed at both ends. A single mouse produces 50–75 droppings per day; rats produce fewer (40–50) but much larger ones.
  • Body size — Adult mice are small, 2.5–4 inches in body length (tail adds another 3–4 inches). Adult Norway rats (the most common species in the Midwest) are much larger — 7–10 inches in body length with a thick, heavy build
  • Ears and eyes — Mice have large ears relative to their head size and large eyes. Rats have smaller ears proportional to their head and small, dull-looking eyes
  • Tails — Mouse tails are thin, lightly haired, and roughly as long as the body. Rat tails (Norway rat) are thick, scaly, shorter than the body, and distinctly different in texture
  • Head shape — Mice have a more pointed, triangular snout. Norway rats have a blunt, rounded muzzle
  • Tracks — In dusty areas, rat tracks show much larger pad and claw prints. Mice leave tiny, delicate footprints
  • Gnaw marks — Both gnaw, but rat teeth are larger and leave rougher, more ragged marks. Mouse gnaw marks are smaller and cleaner

Behavioral Differences That Help You Identify Them

Behavior is also telling:

  • Habitat — Norway rats burrow. Look for tunnels along foundations, under wood piles, in dense vegetation, and in crawl spaces. Mice tend to nest in tight interior spaces — inside walls, under appliances, in boxes of stored materials
  • Feeding habits — Rats are neophobic (fear of new things) and may initially avoid new bait stations. Mice are curious and tend to investigate new objects quickly
  • Activity — Both are primarily nocturnal, but mice especially are rarely seen during the day. Seeing either species in daylight suggests a large population or extreme resource competition
  • Entry points — Mice can squeeze through a gap the size of a dime (1/4 inch). Rats need about a half-inch opening but will gnaw to enlarge it

Why It Matters for Control

Treatment strategies differ between rats and mice:

  • Trap sizing — rat traps are too large to properly trigger on mice, and mouse traps are too small to be effective on rats
  • Bait station placement — rats prefer to travel along walls and established pathways; placement and anchoring strategies differ
  • Entry point identification — the size of gap to seal, and where to look for it, differs based on the species
  • Population dynamics — mice reproduce faster (a single pair can produce hundreds of offspring in a year); rats breed more slowly but are individually harder to eliminate

Misidentifying the species can lead to using the wrong traps in the wrong locations — and wasted time while the infestation grows.

When to Call a Professional

If you’re finding droppings, hearing scratching in walls at night, noticing gnaw marks, or smelling a musky odor in enclosed spaces — it’s time to call someone. Rodent infestations grow quickly and are difficult to fully eliminate without addressing entry points, nesting areas, and the full population.

DIY trapping often captures some rodents while missing the majority of a population. It also doesn’t address how they got in — which means new rodents continue entering as others are removed.

What Miller Pest Solutions Does About Rodents

Miller Pest Solutions provides comprehensive rodent control for homeowners and businesses in Des Moines, Kansas City, and Omaha. We’ve been in business since 2001 — family-owned, QualityPro Certified, and experienced with the rodent pressure specific to Midwest climates and building types.

Our approach starts with identifying the species and the extent of the infestation. We locate entry points, set appropriately-sized and placed traps and bait stations, and develop a plan to seal the home against future intrusion. We don’t just reduce the problem — we work to eliminate it and keep it eliminated.

Learn more at our rodent control page.

Get a Free Phone Bid

Not sure if you have rats or mice — or what to do about it? Call Miller Pest Solutions for a free phone bid. We can help you identify what you’re dealing with and explain your options. Des Moines: (816) 420-0340, Kansas City: (816) 409-3884, Omaha: (402) 532-8863. Or request a quote online.