Getting rid of silverfish may not be as vital for your health as dealing with other pests is, but silverfish are still quite a nuisance to most homes. If you’re wondering “What do silverfish do and why should I care?”, then you’ve been lucky enough not to have them in your home, destroying your books, photo albums, important documents or contaminating your dry food supply.
These pesky, prehistoric critters may multiply slowly but they are also hard to deal with and can cause quite a bit of damage in the meantime. So, to learn how to eliminate silverfish and how to prevent silverfish, this article will explain everything there is to know about them.
In this article:
- Signs of a silverfish infestation
- Silverfish identification
- Primary silverfish control and prevention steps
- Silverfish control methods and products
- Hiring a professional
Signs of a silverfish infestation
Like most other pests, silverfish are sneaky and careful not to be spotted. In fact, they rely on secrecy more than others as they reproduce and mature more slowly than most other insects or even than many rodents. Therefore, silverfish rely on staying out of sight – they are nocturnal and spend most of the daytime hidden in their holes, cracks, and crevices. They are also very quick on their feet and will usually hurry to hide the moment you turn the lights on. That’s why most of the silverfish infestation signs revolve around the damage they leave in their wake. Here’s what to look out for:
- Seeing the silverfish themselves: They may be sneaky but they are not invisible. You are most likely to see a silverfish on your bookshelf or inside your books, as well as in or around any other paper item. You may also find them near your hairbrush or on the bathroom floor as they also feed on dead hair and dandruff.
- Seeing the silverfish damage: As silverfish feed mostly on paper products such as books, photos, documents, and even wallpapers, finding their bite marks on paper is a sure sign of their presence.
- Silverfish droppings or stains: One of the most unpleasant yet common sights, when you have a silverfish infestation, is finding their droppings smeared between the pages of your favorite book.
- Silverfish scales: Silverfish don’t metamorphose after hatching lime most other insects and they simply grow slowly in size throughout their lives. In the process, they molt and shed their scales frequently, leaving them behind. It looks as you’d expect – little, pale scales, fallen on the ground or on the shelves.
Knowing what does a silverfish look like is the first step in dealing with this pest. Silverfish do have a rather unique appearance as they are quite different physically from most other insects. Still, they can be confused with other pests relatively easily, especially by the untrained eye. Other “bristletail” insects, in particular, can be easily confused with silverfish, but they are not all actual pests. Even among the silverfish family, there are only several types that are indoor pests while most of the others are outdoor insects hunt other pests and that may have just briefly wandered through an open window.
So, what are silverfish?
The silverfish insect is actually the oldest living insect on the planet, said to have predated the dinosaurs with over 100 million years. And, as you’d expect, they look very much like prehistoric insects, with their long, carrot-shaped bodies, long antennae and bristles, and sleek fish-like movements.
- In terms of size most indoor silverfish range between 1cm (half an inch) and 2.5 cm (a full inch). Young silverfish nymphs have the same body shape as the adults, only smaller and paler in color. Most silverfish are in a silver-grey color, which is where their name comes from. Some are slightly darker and some have long black stripes on their backs, but they all sill look pretty similar to one another.
- Silverfish breed and mature quite slowly but they also live longer than most other insects. An average silverfish will live for several years (up to 8) and in that period a female will lay a total of about 100 eggs, 1 – 4 at a time. They lay their eggs in hidden holes and cracks after a prolonged mating ritual with their male counterparts. An egg will take between 2 weeks and 2 months to hatch, but once it does, a fully-developed silverfish nymph will appear out of it. Unlike almost all other insects, silverfish don’t change throughout their lives and don’t go through metamorphic stages – they remain the same and only grown in size, regularly molting in the process. Because of their slow breeding and development, silverfish are very careful not to be seen, much more so than other insects. They are nocturnal and very quick to hide when they sense danger.
- Silverfish don’t actually swim despite their name. They are also flightless and can’t jump at all. However, they are far from immobile – they have very quick feet and can run and hide in the blink of an eye. They also have no trouble climbing most vertical surfaces as long as they are not too slippery (like glass) so you can expect to find them high on the walls or shelves in your home. Silverfish won’t bite humans, including kids or even pets as they realize that their jaws and bristles are useless against us. Instead, they rely entirely on the swiftness of their feet.
- Silverfish live on a diet of carbohydrates, sugars, starches, and cellulose. This means that they prefer to feed off of paper, wallpaper, some dried foods, as well as dead hair and dandruff. The feed by simply biting small bits off or scraping away at surfaces.
What causes silverfish?
The key to dealing with these pests is the same as with any other – realizing what attracts silverfish to your home. You’d think as they are literally a prehistoric insect, silverfish would have little care for their living conditions, but that’s not exactly the case. Like anything else on the planet, they too are rather particular as to where they’ll live.
- When wondering where do silverfish live, there are three factors to consider – humidity, temperature, and food sources. We already went over their diet – almost any home will have sufficient food sources for silverfish. As for the other two factors, these insects prefer a relative humidity of 75% – 95% and an average temperature between 21°C and 27°C (70°F – 80°F). Some types of silverfish, such as the Grey/Giant silverfish or the Four-lined silverfish prefer temperatures that are several degrees warmer. As this temperature range fits rather well with our preferred temperatures as well, a good tip for how to keep silverfish away is to lower the relative humidity in your home below 75%.
- Silverfish are known to travel great distances during the small hours of the night in search for food. This often leads them to other people’s homes where they sometimes settle. So, in a lot of cases, silverfish will simply sneak into your home through a window or any crack or crevice they can fit through. Alternatively, you can also accidentally bring silverfish home yourself with books, paper, food, furniture, storage boxes, etc.
- If you are worried that the silverfish in your home can be a sign of a greater problem, then don’t – all these bugs are after is warm temperatures, moist air, and paper to chew on. So the only thing they are a sign of is that your home could use a dehumidifier.
Common silverfish living and hiding places
We mentioned that silverfish require warm temperatures and high humidity, but they are also nocturnal and very sneaky insects that prefer to remain hidden most of the time. So, they tend to live, hide, and lay eggs in small holes, cracks, and nooks. As for the rooms where they might hide, that all depends on whether the temperature, humidity, and food sources are sufficient for them.
Look for silverfish in bathroom hiding spots such as around the bathtub, the plumbing or below the sink. Also check the walls and shelves in your basement, laundry room, garage, and storage areas. The kitchen can also offer a lot of hiding places with cupboards, bookcases, closet shelves, baseboards, etc. Don’t forget to check the window and door frames as well.
That’s for the silverfish in houses but there are also outdoor places where they can live and hide – under rocks and tree bark, leaf mold or other insect’s ants’, and birds’ nests.
How to precisely detect which areas are infested by silverfish?
Given that silverfish are nocturnal, quick on their feet, and not that numerous, there’s little point of trying to find them by yourself in the middle of the night. Instead, if you want to check if you have silverfish or find out which are their preferred travel routes, there are other tricks you can employ.
One good way to detect silverfish, as well as for good silverfish pest control, is to set up traps. These traps can either be DIY homemade traps or commercial silverfish traps. We’ll go over both types in detail below but they generally work like most other insect traps.
Another, even easier, way to detect the presence of silverfish is to smear a mixture of water and flour on an index card near places with suspected silverfish activity. As the silverfish go over the mixture or eats parts of it, they’ll leave marks that will betray their presence.
How to distinguish silverfish from other similar pests (firebrats, earwigs, centipedes, booklice, etc.)?
The first step of silverfish control and silverfish extermination is making sure that you are indeed dealing with silverfish. Unfortunately, there are several other types of insects that can look rather similar to silverish.
- Firebrats look almost exactly like most silverfish and that’s because they are of the same insect order as silverfish – Zygentoma. The appearance difference between firebrats and silverfish is that firebrats are darker and look almost black. They also prefer even warmer temperatures, but, thankfully, what kills firebrats is similar to what kills silverfish.
- Earwigs are another insect that’s also often mistaken with silverfish. In fact, both earwigs and silverfish are subjected to the same wrong myth that they climb into people’s ears at night. They are very different insects, however. For one, they don’t have the signature bristles that silverfish and firebrats have. Instead, earwigs have two pincers on the back of their bodies. Nevertheless, they are harmless to humans unless you try to touch them with bare hands. They are also not pests at all as they don’t harm us or do property damage. Instead, they are an important garden predator to other insect pests.
- Centipedes are another insect that can be confused with silverfish from afar. Up close, however, they are distinctively different as they have dozens of legs and much more elongated bodies.
Primary silverfish control and prevention steps
When pondering how to get rid of silverfish the first thing you should note is that for a sufficient silverfish treatment you’ll need more than just a spray or a trap. Combining a silverfish insecticide together with prevention methods is the best way to achieve a well-rounded and effective result. That’s what’s called Integrated Pest Control approach. Combining several steps and solutions at once will yield a better result and prevent future infestations.
Silverfish don’t come into our homes because they want to be a nuisance to us. You won’t find silverfish in beds or couches because they want to annoy you – it will be because they’ve found adequate conditions for life there. So, to get rid of them, the smartest thing to do is to make sure that your home is less silverfish-friendly.
This may be a painful subject for a lot of people, but regularly cleaning your home and maintaining it clean will result in less dust, dirt, food particles, dead hairs, and dandruff for silverfish to feed on. Additionally, the regular cleaning itself will act as a “natural silverfish repellent” and will even kill off a lot of their eggs.
It’s important to not just clean casually but to make sure that you’re reaching all the cracks and crevices along baseboards, behind appliances, in pantries, cupboards, and drawers, etc. Whenever cleaning, pay extra attention to the bathrooms, shower stalls, laundry rooms, and kitchen.
Removing the household clutter and bringing some order into your home is another vital step to silverfish prevention. Things such as old boxes, stacks of papers, books and magazines, piles of clothes, and so on, can all give silverfish an ample food source. Instead of keeping your books and magazines in the corner or even worse – in the basement or the attic – keep them on a bookshelf where you can dust and clean them regularly.
Good maintenance of your dried foods is also important – keep all flour, pasta, meal, cereals, pet food, grains, and other similar products in airtight sealed containers at all times.
Aside from keeping your home tidy and clean, another good preventive measure against silverfish is to limit their access points into your home. Yes, you might still accidentally bring a stowaway yourself, but at least you’ll greatly reduce the risk of silverfish breaking into your home on their own. Especially if you live in a house with a large garden or with a nearby park/woods, securing your home against silverfish and other insect pests is a great idea. Here are a few good first steps to consider:
- If you’ve already spotted silverfish in your home make sure to investigate where they might be coming from. This will give you a good idea as to what needs to be repaired first, which holes need to be fixed, and so on. This will not only help with the extermination of the current silverfish presence but will be an important future prevention step as well.
- Wrap or insulate the pipes and conduits that lead into your home. Seal all holes and other spaces that silverfish might use to get inside your home. This alone will eliminate a lot of the possible entry points silverfish and other insects use to break in.
- Replace broken floorboards and baseboards, as well as damaged shelves.
- Lower the humidity in your home below 75%. This is especially valid for enclosed and moist rooms such as bathrooms and basements. Using a dehumidifier is a great way to achieve this goal, plus lowering the humidity in your home can help against a myriad of other pests, as well as against the formation of mold.
- Create ventilation in enclosed rooms, as well as in your bathroom, kitchen, garage, attic and other similar spaces.
- Make sure that whatever moisture there is in your home remains trapped under flooring and exterior walls.
- Reduce any excess water in your home. Fix your plumbing and any leaking pipes. This too will be effective against more pests in addition to silverfish but it will also lower your water bill as well.
- Fix or change the window and door frames in your home. You’ll be surprised how many insects can fit through the miniature cracks in a wooden door or window frame – silverfish included. Replacing old and damaged window and door frames will prevent such insect pests from breaking into your home, plus it will make heating your home in the colder months of the year much easier.
Silverfish control methods and products
Now we come to how to kill silverfish. These insects may have survived for hundreds of millions of years but they can still be killed in a myriad of ways. Which method you should choose will be up to your particular situation, the severity of the infestation, as well as additional factors such as the presence of pets and kids, etc.
Keep in mind, however, that when possible it’s best to combine several methods at once for maximum results. This, together with implementing the structural and habitat modification methods we outlined above is what creates the so-called Integrated Pest Management approach. If you just opt for an insecticide spray or essential oils for silverfish alone, you won’t get the best possible results.
Silverfish traps have a dual function – both as monitoring devices and as an answer to the “How to get rid of silverfish naturally?” question. Regardless of the reason why you choose to use silverfish traps, remember that they are as effective as the locations you choose for them are adequate. Even the best silverfish traps will be useless if you place it in a location that isn’t frequently traversed by the insects.
Another point to note is that in cases of more severe infestations, traps won’t be enough to solve the problem on their own. In fact, even for mild infestations traps will mostly serve to keep the pests’ numbers down but not to exterminate them completely. That’s because traps only trap and kill the insects that crawl inside of them but have no effect on their eggs, on silverfish nymphs or on the rest of their population. Still, combined with another control method or product, traps can have a noticeable effect, so don’t ignore them.
DIY silverfish traps
As with any other pest problem, DIY traps can be a good and cost-efficient solution to the problem or a pointless waste of time, depending on how to make them. A good DIY silverfish trap can easily be as effective as a store-bought one, but if the trap you make is ineffective then you would’ve been better off just going to the store right away.
DIY silverfish traps can be made in different designs. The most popular and effective ones come in two forms:
- DIY glue traps: Glue traps are a popular way to hunt and kill all kinds of pests – from silverfish to giant rats. These traps a rather nasty reputation when it comes to mamma pests as they kill them in a rather gruesome manner, but no one seems to mind when they are used against insects. If you want to make some DIY glue traps it’s important to get a powerful adhesive from your local shop and simply smear it on a piece of paper or cardboard. Placing a bait in the middle of the trap can be a good idea – something like a piece of bread or a pile of oatmeal can be good enough. However, you can also just place lots of bait-less glue traps in places that you’ve noticed are frequently traversed by silverfish.
- Glass jar DIY traps: Silverfish are good climbers but even they can’t walk on vertical glass. A good and easy silverfish trap is to take an empty glass jar, tape its outside walls with a tape that silverfish will be able to climb on and place a piece of bread inside. The silverfish will climb inside the jar to get the bread but won’t be able to get out as the inner glass walls of the jar won’t be covered and will be left smooth.
Store-bought silverfish traps
Most store-bought silverfish traps will be very similar to roach traps. In fact, most insect traps are suitable for roaches and silverfish alike and are usually called “cockroach traps/motels” as roaches are a more frequent problem for most people. Whether you get a store-bought glue trap or a roach motel, the key principle remains the same: Location, location, location.
Residual insecticides work on a very simple principle – they are applied on the surfaces silverfish pass through, usually in powder or spray form. Once the insects walk on top of the powdered or sprayed areas, particles of the insecticides stick to their legs and bodies. Some insecticides work by seeping inside the insect through its outer shell while others get consumed by the silverfish while it tries to clean itself. Either way, these are broad-effect insecticides that are meant to target and kill as many insects as possible – silverfish or otherwise.
A lot of residual insecticides are meant to work against a broad spectrum of insects, while some target specific types of insects. Silverfish are typically well-targeted by broader residual insecticides as they are fairly susceptible to the more common active ingredients in these products.
When choosing a residual insecticide to use against the silverfish in your home be careful about its side effects. Depending on the active ingredient inside the product it may or may not be suitable for use around food products or clothes. Also be wary if you have kids or pets as they can touch, lick or inhale the residual insecticides either on accident or intentionally – depending on the active ingredient that can be either harmless or very dangerous.
Insecticide dusts and powders
Dust and powders are generally meant to be applied behind baseboards, in cracks and crevices, in and behind electrical sockets, between pipes and the walls, etc. Most people use dusts and powders rather incorrectly by simply applying them over wide horizontal and open areas, thinking that the pests will just walk over them. And while this is another way powders can be applied, particularly if you encircle the exit hole of the pests so that they are forced to walk over the dust, that’s not the most effective way to use such products.
It’s also important not to confuse dust and powders with granular insecticides. Granular insecticides are intended for outdoor use where they can be applied on the open ground – dust and powders are best used with a hand duster device to “puff” them inside the unreachable holes in our homes that silverfish and other insects love so much.
The main difference between dust, powders and liquid sprays or aerosols (which we’ll go through next) is that liquid sprays and aerosols are more easily sprayed directly over a specific area, while dusts and powders can be “puffed” inside holes and walls where they settle all over the place.
- Boric acid silverfish insecticides are highly effective because not only does it work against silverfish are a lot of other pests, but it’s also less toxic than a lot of other insecticides sold on the market. It is a weak acidic hydrate of boric oxide that has mild antiseptic, antifungal, and antiviral properties.
- Borax, or Sodium Borate, is known as “stomach poison” for a lot of insects and also has effects on their nervous system. It’s the active ingredient in a lot of insecticides but it should be handled with care – keep kids and pets away from it and be careful not to inhale it yourself.
- Diatomaceous earth silverfish solutions are a common tool to use against silverfish or other insect pests. Their pest-grade variants retain high effectiveness when applied correctly while still being one of the non-toxic home remedies for silverfish. Diatomaceous earth (or DE for short) is mined from fossilized remains of microscopic plants (diatoms) that contain silica. It works against insects such as silverfish because once it attaches to their outer shell it removes a portion of their waxy coating and prevents them from retaining moisture. In essence, it dehydrates them to death. Keep in mind, however, that even though DE is non-toxic it still shouldn’t be inhaled or consumed by mammals as larger quantities of it can still have negative health effects. As for food grade DE, as the National Pesticide Information Centre points out, its effectiveness as an insecticide is not examined well enough yet.
- Silica or silica gel is the synthetic variation of Diatomaceous earth. Instead of being mined from plants, silica is synthetically produced, usually from sand. It works on the same principle as pest grade DE.
- Pyrethrin based dusts use a pesticide derived from some chrysanthemum flowers. As the National Pesticide Information Centre described them, Pyrethrins are wide-range pesticides that can kill mosquitoes ants, fleas, moths, and other insects including silverfish. They’ve been used as pesticides since the 1950s and they work by attacking the nervous system of the insects that walk over them, touch them, or eat them. Pyrethrin has low toxicity for humans and mammals but it can still cause some irritation upon skin contact. Inhaling or consuming large quantities of Pyrethrin, however, can cause drooling, difficulty breathing, or even seizures.
The main benefit of aerosols or liquid sprays over dusts and powders is that they can more reliably be applied over the desired surface. Because of their liquid or semi-liquid forms, they stick to the surfaces they are applied to and don’t “puff” all over the places the way powders and dusts do. So, if you have open areas or accessible cracks and crevices that you just want to spray directly in or on, a spray can be effective at that.
- Aerosols or liquid sprays containing Pyrethrin. Pyrethrin in sprays has little difference from Pyrethrin in dusts and powders. It’s the same substance and works in the same way – the only difference is the delivery method.
- Aerosols or liquid sprays containing Pyrethroids. As various Public Health departments point out, Pyrethroids such as Deltamethrin, are the synthetic man-made alternative to nature-derived Pyrethrin. There are over 1,000 different Pyrethroids that have been synthesized by people but only a few are approved for domestic use in most countries. They work in the same way Pyrethrin does by attacking the nervous system of the insects. They are of a similar low toxicity level like the natural Pyrethrin and when inhaled or ingested they cause similar side effects.
Silverfish baits are not much different than most other insect baits – the bait itself can be different but the insecticide in it can be a general one. They work on the idea baiting the bug and poisoning it with a slow-acting insecticide. This will give it time to get back to its colony and spread the poison either by contact or by other – usually young nymph – silverfish feeding on its poisoned feces or corpse. While this method is highly effective at wiping out entire nests and colonies of other insects such as cockroaches, ants, termites, and others, it’s less effective for silverfish. The reason that’s so is because silverfish don’t live in as large colonies as other bugs – if you have silverfish presence in your home, chances are that they are spread across multiple different nooks and crevices instead of living in one big, happy nest.
Still, baits can be effective against silverfish because these insects are not that numerous and getting even just a few kills from a single bait are still a good result.
- DIY silverfish baits: As insecticide baits are fairly simple contraptions to make you can try and craft them yourself. All you need is a bait that silverfish will gravitate toward such as a piece of bread, an index card, or a rolled up newspaper and put some insecticide in it. That insecticide can be Permethrin, Boric Acid, Deltamethrin, Abamectin, Cyfluthrin, Bifenthrin, or another. Keep in mind, however, that whatever you’re using should be handled with care as most of these insecticides – even the less toxic ones – can be unpleasant or outright dangerous upon skin contact or if inhaled.
- Store-bought silverfish baits: A store-bought silverfish bait can be as effective as one you craft yourself or even more so, considering that they are made professionally. They are more expensive than something you can put together on your own but, at the end of the day, they are not that expensive. Silverfish populations are not that large and don’t need a ton of bait to be controlled, after all.
Things that don’t work that well
As with any other insect pest, there are lots of other methods you can try and employ to deal with silverfish. Unfortunately, most of the rest are either grossly ineffective or just not as efficient as the ones we’ve outlined so far.
- The liquid sprays and aerosols we mentioned above were a good solution to the silverfish problem because they are made to leave a dry residue behind them which poisons and kills the insects. They can kill upon contact too but they don’t need to. Non-residual sprays, on the other hand, can only kill on contact as they don’t leave a residue behind them. The benefit of that is that if you have pets or kids there will be no residue for them to come in contact with, but as silverfish are nocturnal and quick on their feet, hitting them with an on-contact non-residue spray is a hard task. Plus, they are harmless so if you have them in your crosshairs you might as well kill them manually.
- Mothballs are something we’ve talked at great lengths. They have their uses and they also have a ton of myths surrounding them, however, they are simply not effective against silverfish. They will repel them from your clothes, which is still something, but they won’t stop them from simply going to another delicious piece of fabric, paper of dried food in your home and chew on that.
- Sprays or sachets made using strongly scented herbs are home remedies that can consist of anything such as cloves, cinnamon, lemon, rosemary, etc. or essential oils like lavender, peppermint, clove, basil, and others. And just like mothballs, while they will have some repelling effect, they will in no way help you deal with the silverfish presence since these bugs can feed on almost anything in your home.
- There are also other natural DIY home remedies such as salt water, citrus fruit sprays, and so on that are sometimes recommended as good natural silverfish treatments. At the risk of repeating ourselves – such remedies might have some repelling effect or may even harm the insect of applied directly on its body, but they won’t work against an entire silverfish infestation because the bugs will simply find something else to chew on.
- Lastly, if you read enough about silverfish control methods online you’ve eventually stumble upon articles about microwave radiation. The simple fact of the matter, however, is that you can’t cover your entire home with microwave radiation – the best you can do is place several books in the microwave oven.
Hiring a professional
Of course, there’s the professional exterminator option as well. When it comes to silverfish, exterminators are rarely called to households because silverfish are neither dangerous to our health nor are they really reaching impressive numbers very often. Still, if you’ve somehow managed to get your home bursting with innumerous silverfish and you want to get rid of them as quickly and as effectively as possible – any insect exterminator will be happy to oblige. They will likely do that for a hefty price too, so the choice is yours.
Most of the time you should be able to exterminate and control a silverfish infestation in your home relatively easily without outside help. But, if money is not a concern and you want to problem solved sooner rather than later, you can hire a professional.
Silverfish really are interesting insects – their prehistoric origins, their unique ametabolous metamorphosis life cycle that’s so different from other insects, as well as their slow reproduction and prolonged lifespan, are all things that fascinate a lot of entomologists. Still, from a homeowner’s perspective they are a nuisance and a pest, so dealing with them quickly and efficiently is vital.
Using the Integrated Pest Management approach against silverfish is the best and fastest way to deal with them. Don’t just use one insecticide or a couple of traps – use a combination of habitat and structural modification fixes and solutions, as well as traps, powdered insecticides, and sprays. Silverfish don’t live in large colonies that include thousands of insects, but in small bands, well hidden from our eyes. So, killing them one by one while also making your home an inhospitable environment for them is the way to go.