Silverfish: How to Get Rid of Them, and When to Call Us
Silverfish are small, silver-grey, wingless insects that feed on starch, paper, glue and fabric. They live where it is dark, damp and undisturbed. A light problem can usually be sorted by drying out the room and clearing paper and cardboard clutter. Benefit Pest Management treats silverfish across Newcastle, Lake Macquarie and the Hunter, with a six month warranty on general treatments, provided the preparation and after-care advice is followed.
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What silverfish are
Most people meet their first silverfish late at night: a silver flicker across the bottom of the bath, or out from behind a row of books nobody has moved in months. It is gone before you get a proper look. Silverfish are not big on introductions. They come out after dark, keep clear of light and settle wherever it is damp and left alone, so the bathroom and the bookshelf suit them down to the ground. Not pleasant to find, and not dangerous either.
Up close, a silverfish is a soft, wingless insect 7 to 10mm long, with a body that tapers towards the tail the way a fish does. Two long antennae stick out the front and three long bristles trail off the back. The whole body is covered in fine silvery-grey scales, and the young start out whitish before they turn silver.
Australia has almost 50 described species of silverfish, and most of them live outdoors under bark, rocks and leaf litter. The house-dwellers are introduced species. The grey silverfish is one of them.
Why they're in your bookshelf and your bathroom
A silverfish needs three things: damp air, something starchy to eat, and a spot nobody disturbs. Between them, a bathroom and a bookshelf cover all three.
The bathroom and the laundry supply the moisture. The common silverfish needs humid air to thrive, around 75% relative humidity or more, and the grey silverfish struggles once the air drops below about 55%. That is why they turn up around showers, baths, basins and the cupboard under the laundry tub.
The bookshelf supplies the food and the quiet. Silverfish can digest cellulose, the plant fibre in paper and cotton. Paper, book bindings, the glue in cardboard boxes and the paste behind wallpaper are all food to them. So are flour, cereal and pet food left open in the pantry and starched cotton and linen in the cupboard. A shelf of books nobody moves gives them darkness, quiet and dinner in one spot.
Wardrobes, linen presses and boxes stored in the roof space work the same way. Anywhere dark, a little damp and rarely opened will do.
Getting rid of silverfish yourself
Dry the room out. Run the bathroom exhaust fan through every shower and for a good while after, and open a window when you can. Fix any dripping tap or leaking pipe. In a closed room that stays damp, a dehumidifier is worth running.
Take away the food. Put flour, cereal and pet food into containers with tight lids. Clear out old newspapers, magazines and cardboard boxes you do not need, especially from cupboards that stay damp.
Clean where they hide. Vacuum along the skirting boards, inside the cupboards and behind the books, then move the books now and again so the shelf stops being undisturbed.
Check it is working. Set a sticky trap in the corner of a cupboard overnight. A glass jar with masking tape wrapped around the outside works as well, because the tape lets them climb in. Fewer in the trap each week means it is working.
Give it a few weeks. Silverfish can go months without food, so a clean-up on its own will not starve them out quickly. The drying out is what moves them on.
If that sounds like a job for your weekend rather than for a pest controller, for a light problem it usually is.
What they damage
Silverfish damage your belongings slowly, and they do it by scraping rather than biting, because their jaws are too weak for much else. On paper and fabric that leaves small, ragged holes. Where they have only scraped the surface, it is left thin and worn.
Book bindings and wallpaper paste are favourites. Old photos, letters and documents kept in cardboard somewhere damp are worth checking first, because a damp cardboard box has the food and the moisture in one place. In the pantry, they contaminate open packets.
The giveaway, apart from the insect itself, is a fine, silvery dust near whatever they have been feeding on. Silverfish keep shedding their skin long after they are fully grown, and that dust is the scales they leave behind.
Professional silverfish control, and the part it can't do for you
When silverfish need more than a clean-up, they are handled as part of a general treatment, which covers the inside and the outside of the house. Inside, we focus on the dark places and anywhere with starch in it, which means the laundry cupboards, wardrobes, linen presses, bookshelves, the bathroom cupboards and the roof space where there is access.
Most treatments hold for three to six months, longer in undisturbed spots such as the back of a wardrobe. General treatments carry a six month warranty, provided the preparation and after-care advice is followed.
What a treatment cannot do is dry out your bathroom. A spray will not fix a broken exhaust fan or a pipe leaking into a wall cavity, and while the damp is still there, the room keeps its appeal for the next lot of silverfish. So the damp has to be dealt with as well as the silverfish, and if we can see where it is coming from, we will tell you.
Ring us on 0467 561 548 and we will talk it through.
Where we do this
We work from our base at Caves Beach across Newcastle, Lake Macquarie, the Hunter, Port Stephens and the Central Coast, with no call-out fee.
Keeping them out
Store papers, photos and spare linen in sealed plastic tubs rather than cardboard. Patch the gaps where pipes come through the walls and the backs of cupboards.
Old books and boxes deserve a quick look before they go on the shelf, because silverfish can live in them and come into the house with them. Damp bathrooms suit drain flies as well, and if you have seen those too, visit our page on drain flies.
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FAQ
What people ask about silverfish
Are silverfish harmful to people?
No. Their jaws are only strong enough to scrape at paper, they have no sting, and they are not known to carry disease. The harm they do is to books, papers, fabric and open food in the pantry, and it happens slowly enough that you have time to deal with it properly.
Why do I suddenly have so many silverfish?
Most likely, a room has become damper or something new has come into the house. A leaking pipe, an exhaust fan that has stopped working or a run of muggy weather can lift the humidity to the level silverfish need. Boxes of old books and papers can carry them in as well.
Does a dehumidifier get rid of silverfish?
It helps, because it takes away the damp they depend on. The grey silverfish dies within about a month in dry air. A dehumidifier works slowly, though, so clear out what they have been eating at the same time and give it a few weeks.
What kills silverfish the fastest?
A household insect spray kills the ones it lands on, but it is unlikely to reach the ones hiding behind the skirting boards and the books. It also will not hold while the damp, the food and the hiding places are still there. For a light problem, drying the room and clearing out their food usually does more than chasing them with a can.
Are silverfish a sign of a damp problem?
Silverfish need humid air to do well, so a steady population can point to somewhere in the house that stays damper than it should: a bathroom without enough airflow or a slow leak under a sink or inside a wall. Fix the damp and they lose their reason to stay.
What's the difference between silverfish and firebrats?
Firebrats are close relatives that like it hot. They are a mottled grey-brown instead of silver, and they turn up near ovens, heaters and hot water pipes. Both eat the same starchy materials and are dealt with in much the same way.
Next step
When drying out isn't enough
If they are still turning up after a few weeks of keeping the bathroom dry and the cupboards cleared out, that is when we are worth a call. Tell us where you are finding them and what you have tried, and we will tell you whether a treatment will help or there is damp to chase first.
A quote costs nothing, and neither does the advice.
Photos come through the form on our contact page.
