Straight answers from a licensed New York exterminator and Associate Certified Entomologist (ACE) — serving all five boroughs, in English and Spanish.
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Quick answer: New York City has two rodents that matter: the Norway rat (large, blunt-nosed, lives in burrows, basements, yards, and the subway) and the house mouse (small, big-eared, lives inside apartments and walls). The animal scurrying along your baseboard is far more likely a house mouse than a baby rat. The fastest tell: a mouse has a head and feet that look small for its body and a thin tail longer than its body, while a young rat has an oversized head and chunky feet. Knowing which you have changes the entire control plan.
“Is that a small rat or a big mouse?” is one of the most common questions I get as an Associate Certified Entomologist in New York City — and getting it wrong sends people down the wrong path. Here is a field guide built for NYC’s actual rodents and NYC’s actual buildings, not a generic suburban page.
NYC’s two rodents
Despite the city’s reputation, NYC is overwhelmingly a two-species town. The Norway rat (Rattus norvegicus) dominates the ground: burrows in dirt and under slabs, basements, alleys, tree pits, parks, and the transit system. The house mouse (Mus musculus) dominates the indoors: it nests inside walls, behind appliances, and in cabinets, and it is the rodent most apartment dwellers actually encounter. Roof rats exist in the U.S. but are rare in NYC; for practical purposes, plan around the Norway rat and the house mouse.
How to tell a house mouse from a young Norway rat
| House mouse | Norway rat (incl. juveniles) | |
|---|---|---|
| Body length | 2.5–4 in | 7–9.5 in (adult); juveniles smaller |
| Head & feet | Small, delicate relative to body | Oversized head and large, chunky feet |
| Ears | Large relative to head | Smaller relative to head |
| Tail | Thin, often longer than body | Thick, scaly, shorter than body |
| Droppings | Rice-grain size (~1/8–1/4 in), pointed | Capsule size (~1/2–3/4 in), blunt |
| Where in NYC | Inside apartments, walls, cabinets | Basements, yards, burrows, ground level |
The droppings test is the most reliable one for most people: mouse droppings are the size of a grain of rice; rat droppings are closer to an olive pit. If you can see chunky feet and an oversized head, it is a young rat, not a big mouse.
Why NYC rodents are a health issue, not just a nuisance. Norway rats and house mice can contaminate food and surfaces and are associated with pathogens including Salmonella, Leptospira (leptospirosis), and, in rare cases, hantavirus. Their continuously growing incisors drive the gnaw marks that damage packaging and wiring. That public-health dimension is part of why NYC treats building-wide rodent control as a property-owner responsibility.
Why the distinction changes the control plan
- House mouse: The problem is inside — sealing interior entry points (gaps around pipes, under cabinets, behind the stove), interior trapping, and sanitation. Mice need only a gap the width of a pencil (about a quarter inch) to enter, so exclusion is detailed indoor work.
- Norway rat: The problem is usually at and below ground level — burrows, basement entry, and exterior pathways. Control means exterior exclusion, addressing harborage and food sources around the building, and sealing basement/cellar entry. Interior traps alone do not solve a rat problem whose source is a yard burrow or a broken cellar door sweep.
This is why a one-size rodent plan fails in NYC. Treating a Norway rat problem with apartment snap traps, or a mouse problem with exterior bait stations, leaves the real source untouched.
What your super must do — and what is on you
In NYC rental housing, keeping the building free of pests (including rodents) is generally the property owner’s responsibility under the Housing Maintenance Code, and chronic conditions can be reported. Practically: report rodent activity to your super or managing agent in writing, and persistent or building-wide conditions can be reported to 311 / HPD. Owners and property managers carry the obligation to address shared causes — basement entry, garbage handling, exterior burrows — that no single tenant can fix. This is general information, not legal advice. For multi-unit buildings, a coordinated program is what works long term; see our multi-unit pest control.
What to do now
Identify the species first (use the droppings and proportions above), then close entry points. For mice, seal interior gaps and set interior controls; for rats, focus on exterior and basement exclusion and harborage. Because NYC rodents exploit the building envelope, durable results come from exclusion and pest-proofing rather than poison alone. New York Exterminating handles both species with rodent control and exclusion, and for attic or wall contamination after an infestation, decontamination and restoration. For a deeper how-to, see our guide to rat and mouse extermination in NYC.
A Brooklyn-based, NYSDEC-registered company (Reg. #15140) led by Jorge Bedoya, an Associate Certified Entomologist (ACE). For mice and rats, NYE provides rodent exclusion that seals the entry points, not just trapping. ACE-led work comes with a client portal of service reports and photos, fully bilingual service, and no long-term contract.
NYC Mice vs Rats FAQ
Is it a baby rat or a mouse?
Look at proportions. A young rat has an oversized head and large, chunky feet relative to its body; a house mouse has a small, delicate head and feet with large ears and a thin tail often longer than its body. Droppings are the easiest tell: rice-grain size means mouse, olive-pit size means rat.
What kind of rats are in NYC?
Almost exclusively the Norway rat, a ground-dwelling burrower found in basements, yards, parks, and the subway. Roof rats are rare in New York City, so rodent plans here are built around the Norway rat and the house mouse.
How small a gap can a mouse get through?
About a quarter inch — roughly the width of a pencil. That is why mouse exclusion is such detailed work: every pipe penetration, cabinet gap, and worn door sweep is a potential entry point.
Does my landlord have to deal with rats and mice?
In NYC rental housing, addressing rodents is generally the property owner’s responsibility, and building-wide or chronic conditions can be reported to 311/HPD. Report activity to your super in writing first. This is general information, not legal advice.
Do I have one mouse or many?
Mice rarely travel alone indoors. Repeated droppings, gnaw marks, or nighttime scratching in the walls usually indicate an established population rather than a single visitor, and warrant inspection before it grows.
Not sure what is in your walls? An Associate Certified Entomologist can identify the species and seal the entry points it is using. New York Exterminating serves all five boroughs, no contracts. Call (347) 210-4646 or see our rodent control service.
Reviewed by Jorge Bedoya, Associate Certified Entomologist (ACE), New York Exterminating.
