Silverfish in the House? How to Get Rid of Them and Fix the Damp That Brought Them

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It usually starts in the bathroom. You switch the light on late at night and something small, silver and oddly fish-shaped darts across the floor and vanishes under the bath panel. A week later there’s one trapped in the basin. Then you notice faint grazing marks on the wallpaper by the toilet and start wondering how many more are hiding in the walls.

If that sounds familiar, take a breath. Silverfish don’t bite, they don’t sting, and the British Pest Control Association (BPCA) says they don’t spread disease. They are a nuisance, and occasionally a destructive one for books, photographs and wallpaper, but they are not a health emergency. More usefully, BPCA points out that a silverfish problem can be a sign of persistent damp, which is worth fixing for its own sake.

This guide explains how to confirm you’re dealing with silverfish, why they’ve moved in, which products genuinely help, and how to use them so the problem doesn’t simply return next winter.

How We Chose These Products

We looked for products sold to UK households that state silverfish (or crawling insects including silverfish) on the label or product listing, and that fit the approach recommended by BPCA: monitor first, fix the damp, then use a labelled insecticide only where an infestation is heavy. We favoured products that can be targeted into cracks and voids rather than sprayed across open rooms, and we’ve flagged where a product is best used as a monitor rather than a cure.

We haven’t laboratory-tested these products. Our recommendations are based on manufacturer information, published guidance from UK pest control bodies and the questions our readers ask us most often. Prices are approximate at the time of writing and change frequently on Amazon.

Quick Comparison

Know Your Silverfish: Common vs Grey

Getting the identification right matters, because the two species you’re most likely to meet in a British home behave differently.

Common silverfish

The common silverfish is a small, carrot-shaped insect, around 12mm long according to BPCA, covered in silvery scales with three bristle-like tails. It loves moisture. BPCA notes it thrives at around 70% humidity, which is why you find it in bathrooms, kitchens, utility rooms and anywhere condensation gathers. It feeds on starchy residues such as wallpaper paste, glue, paper and crumbs, and it hides by day under floor coverings, behind skirting boards and in cracks.

Grey silverfish

The grey silverfish is larger and looks hairier, with very long antennae and tail bristles. BPCA describes a specimen at just under 40mm including antennae and bristles, with a body of around 11mm. The important difference is humidity: BPCA says grey silverfish thrive at around 55 to 60%, so they turn up in bedrooms, living rooms and offices, not just damp rooms. That also means drying out the house alone is less likely to solve the problem, and BPCA notes this species needs a slightly different approach.

Signs you have silverfish

• Silverfish trapped in baths, basins or sinks, often first thing in the morning
• Irregular grazed patches or small holes in wallpaper, book bindings, cardboard or photographs
• Yellowish stains or tiny pepper-like droppings in drawers and cupboards
• Shed skins in quiet corners, behind furniture or in stored boxes
• Insects darting away when you lift a bath mat or move a box in the loft

Because silverfish are nocturnal, BPCA says people often only find out when they spot one trapped in a bath or sink. One sighting doesn’t necessarily mean a large infestation, but several over a couple of weeks suggests a breeding population.

The 5 Best Products for Silverfish, Reviewed

1. Ready Steady Defend Insect Killer Traps (30-pack)

Approx. price: around £17 for 30 traps

These pre-baited paper traps list silverfish as a target species, which makes them our first pick for most homes. BPCA’s advice is to start with an insect monitor to judge how widespread the problem is, and for small infestations monitors may be enough to keep numbers down while you fix the damp. A 30-pack gives you enough to place traps in every likely room, which quickly shows you where the hot spots are.

Pros: no sprays or powders; doubles as a monitoring tool; enough traps to cover a whole house.

Cons: won’t reach silverfish living deep in wall voids; traps fill with dust and need replacing.

Honest caveat: on their own, traps rarely clear a heavy infestation. They’re a measuring tool first and a control method second.

Best for: anyone who’s just spotted silverfish and wants to know how big the problem is. Not ideal for: long-established infestations in older properties with lots of hidden voids.

2. Spider and Crawling Insect Sticky Traps (12-pack)

Approx. price: around £13.50 for 12

These sticky indoor traps are sold mainly for spiders but the listing also mentions woodlice, beetles and silverfish. They’re a good second set of monitors for skirting boards, behind wardrobes and under the bath panel, where silverfish travel at night.

Pros: discreet; easy to slide into tight spaces; also catch spiders that are drawn to silverfish as prey.

Cons: unbaited, so they rely on silverfish wandering across them; less effective than baited traps in open areas.

Honest caveat: glue traps can catch things you didn’t intend. Keep them inside cupboards or behind furniture, never where pets, children or wildlife can reach them.

Best for: tracking silverfish routes. Not ideal for: rooms where pets roam freely.

3. Ant Killer Powder, Up To 6 Months Control

Approx. price: around £6

Despite the name, this powder’s listing says it also targets crawling pests including silverfish, woodlice, beetles and earwigs. Powders are well suited to silverfish because they can be puffed into the cracks, gaps and voids where silverfish hide and lay eggs, and they stay in place in dry voids.

Pros: inexpensive; long-lasting where it isn’t disturbed; reaches places sprays can’t.

Cons: messy if applied carelessly; unsuitable for damp surfaces where it clumps.

Honest caveat: BPCA advises using insecticides for heavier infestations, and only products that are legal, suitable and applied strictly according to the label. Read the label before use and check it’s approved for indoor use in the area you plan to treat.

Best for: treating the gaps behind bath panels, under kitchen units and along skirting boards. Not ideal for: open floors or food preparation areas.

4. Ant and Crawling Insect Killer Spray 250ml

Approx. price: around £8

The product listing states it kills ants, woodlice, cockroaches, silverfish and other crawling insects that come into contact with treated surfaces, leaving a residual barrier. It’s useful for treating the edges of rooms, around pipework and along the junction between floor and wall.

Pros: quick to apply; treats edges and entry points; good partner to a powder.

Cons: won’t penetrate deep voids; residual effect fades with cleaning.

Honest caveat: sprays are for targeted spots, not for misting whole rooms. Over-spraying adds risk without adding results.

Best for: bathrooms and utility rooms once you’ve identified where silverfish run. Not ideal for: households with pets that lick floors, unless the label allows it and you keep them out until dry.

5. Powder Duster Bulb Applicator

Approx. price: around £14

This isn’t an insecticide, it’s the tool that makes powders work properly. A bulb duster lets you puff a fine layer of powder deep into cracks and behind panels instead of leaving heaps on the floor. The listing mentions use with diatomaceous earth and powders for pests including silverfish.

Pros: precise; reduces waste and mess; reusable for other crawling insects.

Cons: powder sold separately; takes a little practice to apply a light, even layer.

Honest caveat: a thin dusting works better than a thick one. Insects avoid heaps of powder.

Best for: anyone using a powder treatment. Not ideal for: people who prefer not to use powders at all.

You’ll find more options on our insect control products and spider and crawling insect control pages.

Silverfish or Something Else? Common Lookalikes

Before you buy anything, make sure the insect really is a silverfish. A few other small household creatures are regularly mistaken for them, and the right fix differs.

• Firebrats: close relatives of silverfish with a mottled grey-brown look. They prefer warm spots, such as near boilers, airing cupboards and ovens, rather than cool damp bathrooms. Treatment is broadly similar, but focus on the warm areas.
• Booklice: tiny, pale, soft-bodied insects only a millimetre or two long, often found on damp books, wallpaper and stored food. Like silverfish, they point to high humidity, and drying the area out is the main fix.
• Woodlice: grey and armour-plated with many legs, they wander in from gardens and damp brickwork. They usually die indoors quickly unless conditions are very damp.
• Carpet beetle larvae: small, hairy, brownish grubs found along carpet edges and in wardrobes. They damage natural fibres rather than paper and need a different approach.

If you trap a specimen, a clear photo next to a ruler makes identification much easier, and it’s useful to show a pest professional if you call one in later. Silverfish have a tapered, carrot-like body, three long tail bristles and move with a distinctive wriggling, fish-like motion, which is where the name comes from.

It’s also worth noting where you find them. Common silverfish clustered in a bathroom point to a moisture issue. Grey silverfish turning up in dry bedrooms and offices, especially in newer buildings, suggest a population living in wall voids and floor gaps, where targeted powder treatment and professional advice are more likely to be needed.

Step-by-Step: How to Get Rid of Silverfish

1. Monitor for a week. Place traps in bathrooms, kitchens, under sinks, behind the bath panel, in wardrobes and in the loft. Check them every couple of days and note where catches are highest.
2. Find and fix the damp. Look for leaking pipes, failed sealant around the bath or shower, blocked extractor fans, condensation on windows and rising or penetrating damp. Fixing these is the single most important long-term step for common silverfish.
3. Reduce humidity. Run extractor fans during and after showers and cooking, open windows when you can, dry laundry outside or in a ventilated room, and consider a dehumidifier in persistently damp rooms.
4. Remove food sources. Store dry foods such as cereal, flour and pasta in sealed containers. Move papers, books and photographs out of cardboard boxes into sealed plastic crates, especially in lofts and garages.
5. Declutter and clean. Vacuum along skirting boards, under furniture and inside cupboards to remove eggs, crumbs and shed skins. Empty the vacuum outside.
6. Seal hiding places. Fill gaps along skirting boards, around pipes and behind tiles with decorator’s caulk or silicone sealant.
7. Treat heavier infestations. If monitors show high numbers after you’ve tackled the damp, use a labelled powder in voids and a residual spray along edges, strictly following the label.
8. Keep monitoring. Leave a few traps in place for at least a month. Eggs laid before treatment can hatch later, so fresh catches in the first few weeks don’t mean you’ve failed.

Health and Safety

Silverfish themselves pose very little direct risk. BPCA states they don’t bite or spread disease. The main risks in a silverfish problem come from the damp that attracts them, and from careless use of insecticides.

• Damp and mould: persistent damp can lead to mould growth, which UK government health guidance links to respiratory problems, eye and skin irritation and effects on mental health. If you’ve found silverfish, check for mould too.
• Insecticides: always wear gloves, read the full label, and keep products away from food, pets, fish tanks and children’s toys. Store them in their original containers, locked away.
• Powders: avoid breathing in dust when applying. A simple dust mask is sensible when filling a duster.
• Rented homes: if the damp is caused by a structural problem or a leak, report it to your landlord in writing. Tenants shouldn’t have to fix structural damp themselves.

When to Call a Professional

Most silverfish problems respond to damp control and targeted DIY treatment. Consider a professional if:

• You’re still catching large numbers after a month of monitoring, damp control and treatment
• You suspect grey silverfish spread through bedrooms and living areas
• Valuable books, archives, artwork or collections are at risk
• You run a business such as a café, care home or clinic, where any insect sighting is a problem

BPCA recommends using a member company, which should have trained technicians, insurance and EN 16636 assessment. You can also request help through our pest control service page.

Seasonal Activity Calendar

Silverfish are active all year indoors, but sightings follow the moisture in your home.

• Winter (December to February): peak sightings in many homes. BPCA notes silverfish tend to be more active in winter, when condensation builds up. Focus on ventilation and drying laundry properly.
• Spring (March to May): a good time to fix sealant, check gutters and treat voids before summer.
• Summer (June to August): fewer sightings in well-ventilated homes, but bathrooms and lofts can still harbour them. Keep monitors in place.
• Autumn (September to November): heating comes on and windows close, so humidity rises indoors. Reset monitors and check problem areas before winter.

Frequently Asked Questions

Are silverfish harmful to humans?

No. According to BPCA, silverfish don’t bite or spread disease. They can damage paper, wallpaper, textiles and stored food packets.

Do silverfish mean my house is dirty?

Not at all. Common silverfish are drawn to moisture, so a spotless home with a condensation problem can still attract them. They’re more a sign of damp than of poor hygiene.

How long do silverfish live?

BPCA says adult silverfish can live for more than three years, which is one reason an infestation can persist if conditions stay favourable.

Will a dehumidifier get rid of silverfish?

For common silverfish, reducing humidity makes a real difference and helps prevent them returning. Grey silverfish cope with drier air, so a dehumidifier alone is less likely to solve that problem.

Can silverfish damage books and photos?

Yes. They feed on starch and glue, so book bindings, old photographs, cardboard and wallpaper are all at risk. Store valuables in sealed plastic containers off the floor.

Do ultrasonic repellers work on silverfish?

We don’t recommend them. Regulators have challenged marketing claims for ultrasonic pest devices, and there’s no good evidence they control crawling insects.

Shop the Full Range

Browse our insect control range, see traps and sprays in spider and crawling insect control, or compare multi-insect powders in our ant and crawling insect products.

Sources: BPCA: silverfish could point to problems with damp; BPCA Pestwatch: silverfish and grey silverfish; GOV.UK: health risks of damp and mould in the home

This guide was written based on our experience advising UK homeowners and renters on pest problems, combined with published guidance from the British Pest Control Association and UK government health guidance. It’s general information, not a substitute for a professional survey. Always read and follow product labels.