Silverfish in the House: Why They're There and How to Get Them Out

If you've flicked on the bathroom light and watched a silvery shape bolt across the floor, you've met the household silverfish. "Silverfish in the house" is one of the most common pest searches in New Zealand — and the good news is that a silverfish in your home is a fixable problem, not a permanent housemate.

Here's why silverfish move indoors, which rooms they favour, and how to get them out without reaching for harsh chemicals.

Why do silverfish come inside houses?

Two things pull silverfish into a Kiwi home: moisture and food. Silverfish need humidity to survive and breed, so any house with a damp bathroom, a leaky pipe, a humid laundry or a poorly ventilated roof space is prime territory. They also feed on starch and cellulose — paper, book glue, wallpaper paste, photos, cardboard, cereals and natural fabrics — which means most homes offer both a drink and a meal.

A silverfish bug in the house is rarely a sign of a dirty home. It's a sign of a damp one, or one with plenty of dark, undisturbed paper and cardboard to feed on.

Which rooms do silverfish favour?

• Bathrooms and laundries — warm, humid and full of hiding spots behind appliances and under sinks.
• Kitchens and pantries — starchy food, cardboard boxes and gaps behind cupboards.
• Roof spaces and basements — dark, still and often damp, with stacks of stored papers and boxes.
• Wardrobes and bookshelves — natural-fibre clothing, books and photos are all on the menu.

Signs you have household silverfish

• Silvery, teardrop-shaped insects 10–20 mm long darting away when you turn on a light.
• Shed silvery, paper-thin skins in dark corners, drawers or under books.
• Tiny black, peppery droppings on shelves and inside cupboards.
• Small irregular holes and yellowish stains in books, wallpaper, photos or stored clothing.

How to get silverfish out of your house

1. Dry the home out

Moisture is what keeps silverfish indoors. Fix leaky pipes and taps, run a dehumidifier or open windows in damp rooms, ventilate the roof space, and use extractor fans when showering or cooking. Bringing humidity below 50% makes a home genuinely hostile to silverfish.

2. Remove their food and hiding spots

Store books, papers and photos in sealed plastic tubs rather than cardboard boxes. Keep pantry starches — flour, cereal, pasta — in airtight containers. Declutter old boxes and paper piles, vacuum along skirting boards and behind appliances, and seal cracks around pipes and skirting boards where they hide.

3. Trap the stragglers

Place a reusable silverfish trap in the dark, damp spots where you've seen them — under sinks, in wardrobes, near bookshelves and along skirting boards. A baited trap catches silverfish where they're most active, and because it's reusable you can refresh the bait each season instead of throwing the trap away.

How to keep silverfish from coming back inside

Once the numbers are down, keep them out by staying on top of humidity, keeping paper and fabric in sealed storage, and leaving a trap in the rooms they favoured. A household that's dry and free of loose cardboard and paper is a household silverfish have no reason to enter.

Silverfish in the house — frequently asked questions

Is one silverfish in the house a problem?

One at night is normal. Several during the day, or sightings in multiple rooms, signal an infestation — silverfish hide by day, so a few visible usually means many more hidden.

Are silverfish inside the house dangerous?

Not to your health — they don't bite, sting or spread disease. The damage is to books, papers, photos, wallpaper and stored clothing, which they chew for starch and cellulose.

What's the fastest way to get silverfish out of my home?

Drop the humidity, clear their food and hiding spots, and set a baited reusable trap in the damp rooms they favour. The combination of moisture control and trapping is what clears a household silverfish problem for good.