NYC Pest Library
The four rodent species found in New York City
Know Your Rodent
NYC has four species of rodents that account for virtually all residential and commercial infestations. Two are rats, two are mice — and each requires a different treatment approach. The size of the droppings, the location of activity, the sounds you hear, and the type of damage all point toward which species you're dealing with.
Correct species identification is the first step in effective treatment. A Norway rat job is structurally different from a roof rat job. A house mouse infestation in a pre-war apartment building requires different methods than a deer mouse situation in a Staten Island home. Each profile below covers identification, signs, NYC-specific behavior, and how we treat them.
Norway Rats
Rattus norvegicus
NYC's most common rat species
Norway rats are the defining pest problem of New York City. They are the large, brown, ground-dwelling rats that burrow under sidewalks, nest alongside sewer lines, and run through subway stations. No other rodent species is as closely associated with NYC's rodent problem as Rattus norvegicus.
Key Signs
- —Burrows in yards, gardens, or alongside building foundations — round holes 2–4 inches in diameter with loose soil around the entrance
- —Gnaw marks on wood, plastic, and soft metals around food storage areas and utility penetrations
- —Greasy rub marks along baseboards, wall bases, and pipe runs from the oil in their fur leaving brown smear trails
Roof Rats
Rattus rattus
The climber rats nesting above you
Roof rats are the other rat species found in New York City — smaller, sleeker, and dramatically better climbers than Norway rats. Where Norway rats dominate the underground and ground-level infrastructure of the city, roof rats occupy the upper floors, attics, cornices, rooflines, and tree canopies of outer-borough residential neighborhoods.
Key Signs
- —Scratching and running sounds in attic spaces at night — lighter and faster than Norway rat sounds, often described as pattering
- —Droppings in attic insulation, along upper-floor ceiling edges, or near roof penetrations
- —Gnaw marks around roof vent openings, soffit edges, and any wood trim at the roofline
House Mice
Mus musculus
The most common NYC apartment pest
House mice are the most common rodent pest in New York City apartments, pre-war buildings, and commercial kitchens. They are present in every borough, every neighborhood, and virtually every building type that existed before 2000. The same pre-war construction characteristics that make NYC buildings vulnerable to rat entry — continuous wall cavities, unsealed pipe penetrations, aging masonry — make them even more accessible to mice, which can fit through any gap larger than a dime.
Key Signs
- —Small dark droppings (1/4 inch, pointed ends) along baseboards, behind appliances, and inside kitchen cabinet bases
- —Gnaw marks on food packaging, cardboard boxes, and soft plastic containers — often the first sign homeowners notice
- —Scratching sounds in walls at night — lighter and more rapid than rat sounds, often with a faint squeaking component
Deer Mice
Peromyscus maniculatus
Outer-borough mice with serious disease risk
Deer mice are less common in dense urban NYC than house mice, but they carry a disease risk profile that makes careful identification and specialized removal essential when they are present. Unlike house mice, deer mice are a primary reservoir for hantavirus pulmonary syndrome (HPS) — a serious respiratory illness with a significant mortality rate that is transmitted through inhalation of disturbed droppings, urine, or nesting materials.
Key Signs
- —Droppings in basement storage areas, garages, and utility spaces near exterior walls — different distribution pattern than house mice
- —Nesting material (grass, plant fibers, cotton, insulation) in rarely disturbed spaces like stored boxes, seasonal equipment, or crawl spaces
- —Direct sightings in outdoor areas adjacent to the structure — wood piles, dense plantings, and ground-level clutter near the foundation
Quick Identification Guide
| Species | Size | Dropping Shape | Where Found |
|---|---|---|---|
| Norway Rat | 7–10″ body | 3/4″, capsule, blunt ends | Basement, burrows, ground level |
| Roof Rat | 6–8″ body | 1/2″, spindle, pointed ends | Attics, rooflines, upper floors |
| House Mouse | 3–4″ body | 1/4″, rod-shaped, pointed | Walls, kitchens, any floor |
| Deer Mouse | 3–4″ body | 1/4″, pointed, dark | Outer boroughs, garages, storage |
Not sure which species you have? A free inspection will confirm it.
Not Sure What You Have?
A free inspection will tell you exactly what species, how severe, and what the treatment scope looks like.
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