Silverfish are a moisture problem before they're an insect problem. They need high humidity to survive and reproduce, which is why they show up almost exclusively in damp basements, bathrooms, laundry rooms, and around leaking pipes rather than throughout a whole home evenly. Brooklyn Heights and Carroll Gardens' older brownstone basements, with original masonry and ground-level moisture, are typical silverfish habitat.
Once established, silverfish feed on cellulose and starch-based materials — book bindings, wallpaper paste, cardboard, some paper goods, and certain synthetic fabrics. They're a genuine property-damage pest for anyone storing books, documents, or photographs in a damp basement or closet, but they don't bite, sting, or spread disease — the concern is what they eat, not health.
Flatbush's mix of older apartment buildings and row houses, and Sunset Park's older multi-family stock, both see recurring silverfish activity tied to bathroom and basement humidity that never gets fully resolved between visits. A one-time insecticide treatment without addressing ventilation or a leak tends to see the population return within a season.
What attracts silverfish, what do they damage, and how do you get rid of them in a NYC home?
The University of California IPM program describes silverfish as shiny, silver to pearl-gray and about half an inch long, with two long antennae and a body tapering to three thin, tail-like appendages; near-identical firebrats are a mottled gray-brown, so finding their dustlike, slightly incandescent shed scales beside damaged items is the surest way to tell which pest you have. (UC Statewide IPM Program — Silverfish and Firebrats)
Silverfish are a moisture problem first: the UC IPM program reports they thrive in damp, warm conditions, favouring relative humidity above 75 percent, and commonly infest basements, laundry rooms and bathrooms — the exact damp pockets of a NYC apartment or brownstone where humidity is rarely controlled. (UC Statewide IPM Program — Silverfish and Firebrats)
Penn State Extension reports that silverfish and firebrats can destroy cereals, books, paper, wallpaper and other starchy items, and UC IPM notes the damage shows as irregularly shaped holes because the insects scrape rather than bite the surface — feeding on paper sizing, book bindings, wallpaper paste and the starch in stored clothing. (Penn State Extension — Bristletails (Silverfish and Firebrats))
Penn State Extension advises that no single method controls silverfish: effective management combines sanitation, de-humidification, habitat modification and only targeted insecticide, cutting off food, water and harbourage at once. UC IPM adds that dehumidifiers and fan ventilation can lower humidity to intolerable levels, with chemical use reserved for large infestations. (Penn State Extension — Bristletails (Silverfish and Firebrats))
Silverfish vs firebrat — how to tell them apart
| Silverfish | Firebrat | |
|---|---|---|
| Colour | Shiny silver to pearl-gray | Mottled gray or brown |
| Size | About 1/2 inch | About 1/2 inch |
| Preferred conditions | Damp and warm, humidity above 75% | Very hot and drier, above 90°F |
| Where found | Basements, laundry rooms, bathrooms | Near ovens, hot-water pipes, furnaces, summer attics |
Signs you have a silverfish control problem
- Small, silver-grey, wingless insects with a tapered, fish-like body seen at night in bathrooms or basements
- Small irregular holes or yellowish stains on paper, book bindings, or wallpaper
- Fine, pepper-like droppings near stored paper goods or cardboard boxes
- Shed skins (silvery, scale-like) accumulating in a damp closet, basement corner, or under bathroom fixtures
- Activity concentrated in one consistently humid room rather than spread through the whole home
Why Park Slope sees this
Brooklyn Heights and Carroll Gardens' older brownstone basements, with original masonry and ground-level dampness, are classic silverfish habitat — the age of the housing stock matters more here than in newer construction.
Flatbush and Sunset Park's older multi-family buildings see the same pattern in bathrooms and basements, where humidity that never gets fully addressed between treatments is why silverfish activity tends to return within a season rather than staying gone.