Silverfish thrive in apartments because these spaces often provide exactly what they need: warmth, moisture, and starchy materials to feed on. Getting rid of them requires a combination of cutting off their water supply, removing food sources, sealing entry points, and in some cases using targeted treatments. The good news is that most apartment silverfish problems can be resolved without professional help.
Why Silverfish Are in Your Apartment
Silverfish are moisture-dependent insects that prefer temperatures between 71°F and 90°F with relative humidity above 75%. Apartments with leaky pipes, poor ventilation, or damp bathrooms and laundry areas create ideal breeding grounds. In multi-unit buildings, they travel through wall voids, along baseboards, and through gaps around plumbing, so even a clean apartment can get silverfish migrating from a neighboring unit.
They feed on an unusually wide range of materials. Cereals, flour, pasta, pet food, and dried meat are all fair game. But silverfish also have gut enzymes that digest cellulose, which means they’ll eat paper, book bindings, wallpaper paste, cardboard boxes, and starched linens. Household dust, dead insects, and even certain fungi round out their diet. If you have stacks of old magazines, cardboard storage boxes, or open pantry items, you’re essentially setting a table for them.
Lower the Humidity First
Reducing moisture is the single most effective long-term strategy. The EPA recommends keeping indoor humidity between 30% and 50%, and maintaining levels at or below 60% makes your apartment significantly less hospitable to silverfish. A small dehumidifier in problem areas like bathrooms, closets, or laundry rooms can make a noticeable difference within days.
Beyond a dehumidifier, check for hidden leaks under sinks, around toilet bases, and near sweating pipes. Even slow drips create enough moisture to sustain silverfish populations. Run exhaust fans during and after showers, and avoid drying clothes indoors without ventilation. If your apartment has poor airflow in closets or storage areas, a small fan can help circulate air and prevent moisture from settling.
Remove Their Food Sources
Store dry goods like flour, cereal, pasta, and pet food in airtight containers rather than leaving them in original packaging. Silverfish can chew through paper and thin plastic with ease. Vacuum regularly, especially in corners, along baseboards, and behind furniture where dust and debris accumulate. Household dust alone provides enough nutrition to keep silverfish alive.
Reduce paper clutter wherever possible. Old newspapers, cardboard boxes used for storage, and stacks of magazines are prime feeding spots. Switch to plastic storage bins with tight lids. If you have books you want to protect, keep them in low-humidity areas and consider storing rarely used ones in sealed containers. Starched linens, silk, and cotton items stored in open closets are also vulnerable, so keep these in sealed garment bags or bins.
Seal Entry Points
In apartments, silverfish move through wall voids and gaps that are easy to overlook. Focus your caulking efforts on these key areas:
- Pipe openings: Gaps around plumbing under kitchen and bathroom sinks are common entry points. Seal them with silicone caulk or expanding foam.
- Cabinet bases: The space where cabinets meet the wall or floor often has small gaps. Run a bead of caulk along these seams.
- Baseboards and trim: Silverfish travel along wall edges where trim meets the floor. Seal any visible gaps.
- Electrical outlets and light switches: On shared walls especially, these openings provide direct access between units. Foam gasket inserts (available at hardware stores) fit behind the cover plates.
You won’t be able to seal every possible route in an apartment, but closing the obvious gaps dramatically reduces how many silverfish can move into your space from elsewhere in the building.
Powder Treatments That Work
Diatomaceous earth (DE) is one of the most effective non-toxic options. It’s a fine powder made from fossilized aquatic organisms that works by puncturing the insect’s exoskeleton, causing it to dehydrate and die. Apply a light dusting in cracks, behind appliances, under sinks, along baseboards, and inside cabinet voids. Use food-grade DE and keep the layer thin. Silverfish will actually avoid heavy piles of powder.
Boric acid is another option and is particularly useful because it kills both silverfish and their eggs. You can apply it as a dust in the same locations as DE, or mix it with flour or sugar in a shallow dish to create a simple bait trap. However, boric acid is toxic to pets and young children, so it should only be used in areas they can’t access, like behind appliances, inside wall voids, or on high shelves.
Both powders lose effectiveness when wet, so reapply them if they get damp. In dry, undisturbed locations like closet corners or behind a refrigerator, a single application can remain active for months.
Traps and Spray Options
Sticky traps placed along baseboards, inside closets, and under sinks serve two purposes: they catch silverfish directly and help you identify where activity is highest. Place them flat against walls since silverfish travel along edges. Check traps weekly and move them if they’re not catching anything.
Commercial insecticide sprays designed for indoor use typically contain pyrethroids, synthetic versions of a natural compound found in chrysanthemum flowers. These are effective as a barrier treatment when sprayed along baseboards, door frames, and other entry points. Follow label directions carefully: apply only the recommended amount and ventilate the area after spraying. People with respiratory conditions should be cautious, as pyrethroid sprays can irritate airways. Skin contact poses minimal risk since pyrethroids are poorly absorbed through skin.
Natural Repellents
Cedarwood oil works by disrupting the pheromone signals silverfish use to navigate, find food, and breed. Applying diluted cedarwood oil along baseboards, inside closets, and in storage areas can deter silverfish from settling in those spots. You can also place cedar blocks or chips in drawers and closets. Whole cloves tucked under sinks or in closet corners offer a similar repellent effect thanks to their strong scent.
These natural options work best as part of a broader strategy rather than a standalone fix. On their own, they may push silverfish to other areas of your apartment rather than eliminate them. Pair repellents with humidity control and food source removal for lasting results.
What Silverfish Can and Can’t Do to You
Silverfish don’t bite and won’t make you sick directly. They can contaminate food by leaving droppings in open packages, so discard any food where you spot insects or their waste. Their droppings also leave small dark stains on fabric and paper.
One lesser-known concern: silverfish shed tiny scales throughout their lives, and these scales contain proteins similar to dust mite allergens. If you’re prone to allergies, a silverfish population in your home can trigger symptoms like a runny nose, sneezing, or itchy eyes. Reducing their numbers and vacuuming regularly helps minimize this.
The real damage is to your belongings. Silverfish chew irregular holes in paper, books, wallpaper, and fabrics. They prefer starchy and glazed paper, so photo prints, old documents, and glossy magazines are particularly at risk. Clothing made of silk, cotton, or any starched fabric can also sustain damage over time.
When the Problem Keeps Coming Back
Apartment silverfish infestations are stubborn when the source is a building-wide moisture issue or a neighboring unit. If you’ve reduced humidity, sealed gaps, and applied treatments but still see silverfish regularly, the problem likely extends beyond your unit. At that point, contact your landlord or property management. Many leases require the building owner to address pest issues, and effective treatment in a multi-unit building often means treating common areas, basements, and adjacent units simultaneously. A pest control professional can apply residual treatments in wall voids and utility chases that aren’t accessible to tenants.