Silverfish in NYC Apartments: Why They're There and How to Get Rid of Them

# Silverfish in NYC Apartments: Why They're There and How to Get Rid of Them

Silverfish are one of the most common insects found in Brooklyn, Queens, and Manhattan apartments — but most NYC residents have never heard of them until they see one darting across their bathroom floor at 2 AM. That fast-moving, metallic silver insect disappearing under the baseboard isn't dangerous, but it is a sign that something in your apartment's environment is attracting them. Here's what silverfish actually are, why New York City apartments are particularly vulnerable, and how to eliminate them.

What Are Silverfish?

Silverfish (*Lepisma saccharina*) are small (1/2 to 3/4 inch), wingless insects with a distinctive silvery-gray color and fish-like movement — a rapid side-to-side wiggling motion that gives them their name. They have three long tail-like appendages at the rear and two long antennae. They are completely harmless to humans — they don't bite, sting, or transmit disease. But they do feed on paper, cardboard, book bindings, wallpaper, linen, silk, and starchy foods. In large numbers they can damage books, documents, and clothing.

Silverfish are ancient insects — they have existed largely unchanged for 400 million years. They thrive in conditions that NYC apartments provide in abundance: high humidity, darkness, and plenty of starchy organic material to eat.

Why NYC Apartments Are Especially Prone to Silverfish

The combination of factors in typical Brooklyn, Queens, and Manhattan apartments creates ideal silverfish conditions:

Older building plumbing: Pre-war buildings throughout Brooklyn Heights, Park Slope, Astoria, and Jackson Heights have aging pipes with frequent slow leaks and condensation issues. Silverfish need humidity levels above 75% to thrive — a leaky pipe under a bathroom sink or inside a wall creates the perfect microclimate.

Shared walls and plumbing stacks: Silverfish travel through shared wall voids and along plumbing stacks. In multi-unit buildings, a silverfish infestation in one apartment spreads to adjacent units via these pathways. You can do everything right in your own apartment and still have silverfish if a neighboring unit has an untreated moisture problem.

Abundance of food sources: NYC apartments tend to have dense book collections, abundant cardboard (Amazon deliveries), paper bags, and linens stored in closets — all silverfish food sources. Bathroom wallpaper, plaster dust, and dried organic residue in wall voids are additional food.

Basements and sub-grade units: Ground-floor and garden-level apartments in Brooklyn and Queens brownstones are especially prone to silverfish due to higher ground moisture, proximity to the soil, and the condensation patterns of below-grade spaces.

Where to Find Silverfish in Your Apartment

Silverfish are nocturnal and photophobic — they scatter when lights come on, which is why most people see them briefly and then lose them. The most common locations in NYC apartments:

• Bathroom: Under the sink (especially near any leak or moisture), along the baseboard near the tub, under loose floor tile or around the toilet base

• Kitchen: Under the sink, in the back of lower cabinets, along baseboards near the refrigerator

• Bedroom and closets: In stacked books, in paper bags stored in closet floors, behind dressers pushed against exterior or bathroom walls

• Bathroom and kitchen ceilings: Silverfish are excellent climbers and often enter ceiling voids from wall stacks

Signs of Silverfish Beyond Seeing the Bug

• Yellow staining on paper: Silverfish excrement leaves yellowish staining on paper and books

• Irregular feeding marks: Irregular chewed areas on paper, book bindings, or cardboard (unlike termites, the feeding marks are surface-level, not structural)

• Shed skins (exuviae): Silverfish molt throughout their lives; finding tiny translucent husks in closets or behind books indicates silverfish activity even if you haven't seen a live bug

• Notched fabric: Silverfish will feed on natural fiber clothing, linen, and silk stored in closets — particularly items with starch residue from dry cleaning

How to Get Rid of Silverfish in Your NYC Apartment

Getting rid of silverfish permanently requires addressing both the population and the conditions that support it.

Step 1: Reduce humidity

This is the most important long-term fix. Check under bathroom and kitchen sinks for slow drips or supply line condensation. Report any leaks to your landlord in writing (in NYC, landlords are legally required to address plumbing leaks). Use a dehumidifier in rooms above 50% humidity. In Brooklyn and Queens basement apartments, this may mean a dehumidifier running continuously.

Step 2: Reduce food sources

Move paper bags and cardboard boxes out of kitchen and closet floors. Store books in sealed boxes if you have heavy silverfish activity. Move stacked magazines and newspapers off the floor. Check for any cardboard-backed shelving in closets.

Step 3: Seal entry points

Silverfish enter apartments from wall voids and plumbing chases. Seal gaps around pipes under sinks with expandable foam or silicone caulk. Check where the baseboard meets the floor in bathrooms and closets — gaps here are a primary entry route.

Step 4: Targeted treatment

Desiccant dusts (such as diatomaceous earth or silica gel dust) applied into wall voids through outlet plates, under baseboards, and in closet corners kill silverfish through physical desiccation. Professional applications reach harborage areas that surface sprays don't penetrate. Residual treatments in high-activity areas combined with the moisture reduction steps above produce lasting results.

Step 5: Laundry

If you've found silverfish in your closet, wash any natural-fiber clothing that may have been affected on high heat. This kills any eggs laid in fabric.

Do Silverfish Mean Your Apartment Has a Bigger Problem?

Not necessarily — silverfish can establish in any apartment with sufficient moisture and food. However, heavy silverfish activity (seeing multiple bugs regularly) combined with other signs — peeling wallpaper, a musty odor, or evidence of moisture in walls — may indicate a building moisture problem that your landlord needs to address. In NYC, landlords are responsible for maintaining apartments free from moisture conditions that cause pest infestations.

When to Call a Professional

If silverfish activity persists despite reducing humidity and removing food sources, a professional treatment is the most effective next step. In multi-unit buildings, professional treatment combined with landlord notification about moisture issues addresses both the population in your unit and the source conditions in shared wall voids. Jet Pest Control serves Brooklyn, Queens, Manhattan, Nassau County, and Suffolk County with targeted silverfish treatments and moisture problem assessments.

Call (718) 710-0330 (Brooklyn, Queens, Manhattan) or (516) 774-5051 (Nassau, Suffolk) for a silverfish inspection. Unmarked vehicles; discreet professional service throughout New York.