In this article we’ll answer the question, should you be worried if you see one silverfish in your home?
Even those of us that do not get grossed out by bugs may be surprised when they spot a silverfish at home.
These tiny insects are not seen too often, given that they are both nocturnal and can scurry at lightning speeds across horizontal surfaces if startled or threatened.
As we will see later in this article, it is more likely for us to discover the “handiworks” of silverfish, rather than the insect itself.
Is Seeing One Silverfish Normal? And Should You Be Worried?
So, the question is: if you spot a single silverfish, should you be worried? The answer is “yes”, especially if you like having your household fixtures, furnishings and food left alone.
The good news is that unlike roaches, for example, silverfish do not spread disease, nor do they bite, scratch or sting like mosquitoes or yellow jackets. They can, however, do a lot of damage if unleashed in force.
Therein lies the rub – if you do spot a silverfish, the chances are high that it is not alone but part of a colony of hundreds, possibly living inside your wall space or other damp areas. A lone silverfish may well be the harbinger of a more serious infestation.
It may also signal that your living conditions are unhygienic and/or unhealthy, given the environment silverfish tend to thrive in. Bottom line – you don’t want to ignore a single silverfish sighting as an anomaly. It’s likely not alone.
What is a Silverfish?
The silverfish is an ancient insect, predating even cockroaches on Earth – their ancestors arose some 400 million years ago. The species has persisted since then.
Common Silverfish (Lepisma saccharinum)
Adult silverfish are silvery grey, with a metallic sheen, tiny (usually between 0.5 to 1 inch in length) and wingless. They can be distinguished by three protrusions from their posterior ends – two cerci spread to the sides and one filament going straight back. Silverfish do possess eyes, unlike many other members of Zygentoma, the order that the silverfish belong to.
The back protrusions are a characteristic of arthropods in Zygentoma. The common silverfish species is Lepisma saccharinum. Other, closely related species found in North America include Ctenolepisma longicaudatum, Ctenolepisma quadriseriatum and the Urban Silverfish (Ctenolepisma urbanum).
The tapering abdomen and the wiggling (fish like) motion of the insect, along with the glint of metallic hues from its body, gives the silverfish its name. They are nocturnal and can be very agile across horizontal surfaces if exposed to light or under threat. They cannot, however, scale walls efficiently.
The name L. saccharinum pertains to the common silverfish’s diet being heavy in starches and sugars.
Do Lone Silverfish Exist?
Many of us may have spotted our first silverfish in the bathroom late at night. We’ve often ignored the sighting of a single insect and moved on. However, we should be aware that lone silverfish are a rarity.
They are prolific breeders – a single female can lay up to a hundred eggs in her lifetime and the larva can become adults in three months. They are also proficient at hiding in warm, moist and dark spaces.
They have an aversion to light in general, particularly sunlight. So, they tend to be nocturnal and stay out of sight during our waking hours.
The reason we don’t spot them as much is that they are tiny, agile and tend to frequent damp spaces such as bathrooms, basements, garages and crawlspaces – plus wall cavities if they can get in.
Given their prolific growth rate, and their long lifespan of up to 8 years in subtropical climates (especially if it’s around 750-850F and damp), it is much more likely that the silverfish you spotted is part of a colony rather than a loner.
Being wingless, the silverfish is less likely to have flown or wondered into your home from outside, as a lone roach may do. It is more likely that a colony of silverfish found a way into your house and then found a warm, moist environment with adequate sources of food. That does not bode well for you.
Finally, silverfish can exist for up to a year without food. At times, you may not even be aware that you have a silverfish colony living on your premises – waiting to come out at the right moment.
What is the Danger of Having Silverfish in Your Home?
As mentioned above, silverfish do not scratch, bite, sting or carry diseases. So, they are sometimes considered more of a nuisance than a pest, especially because they are not readily spotted crawling around the house. However, a major infestation is worrisome due to two reasons:
- It speaks volumes about your own living environment. Having silverfish colonies infest your house usually signifies an abundance of warm, damp and dirty spots, which may turn into mold. They also point to entryways (for silverfish and other pests) which you need to find and seal.
- The second problem is created due to the silverfish’s diet and the havoc they can wreak. More on that in the next section.
Are Silverfish Bad?
While they do not harm humans physically, silverfish have a diet high in proteins and carbohydrates, especially polysaccharides. They will happily munch away at the following items in your house, to name just a few:
- Carpets and carpet glue
- Wallpaper and wallpaper glue
- Books – both pages and bindings – and papers
- Clothing and Linen (esp. cotton, rayon and silk)
- Food (cereal, flour, sugar, fruit juice concentrates, pretty much all sweet stuff)
- Wall tapestries and prints
- Coffee and coffee grinds
A major silverfish infestation can create havoc with your house, with the telltale signs of their damage being everywhere, as described below. They can be responsible for significant damage to your household items, including bedding, furnishings and fixtures.
The fact that they eat dandruff means that you are liable to find them crawling over your bed at night – increasing the nuisance factor. Finally, silverfish regularly gets into food, which then must be discarded for health and safety reasons.
If your house has an environment which is comfortable for silverfish to breed and proliferate, they can grow very fast and overrun the household. Their imprints will be everywhere.
What are the Signs that You May have More than One Silverfish in Your Home?
The biggest signs of a silverfish infestation are usually from the damage they cause, such as torn or half-eaten pages of books and papers, damage to linens and finding them in your food.
Silverfish Damage to Clothes and Books
While there are other insects that could cause more damage to drywall and structure (e.g. termites), silverfish can still cause significant damage to drywalls, wallpapers, carpeting and the like.
Since silverfish are elusive during our waking hours, the first signs you find could be damages like those depicted above – namely irregular feeding marks, whether they be holes, notches along the edges of surfaces or etches on the surface. They also tend to leave yellow stains (when they die) and distinctive, black, pepper/pellet-like droppings on surfaces that they infest.
Why are There Silverfish in Your Home?
Silverfish are attracted to starches and carbohydrates, as well as warm, dark and damp places that are not visited or cleaned often. So, it you tend to leave newspapers, mail and similar items lying around, or if there’s a lot of dust and old, unwashed (dank) clothes, you will attract silverfish.
Food crumbs also do the trick for obvious reasons. Older houses, with crawl spaces, basements, garages, kitchens and bathrooms that often stay damp are havens for the insects, especially in warm, subtropical climates.
Silverfish often live outdoors, and will look to get indoors when (a) there is a source of food and shelter (in other words, your house beckons to them – which is not a good thing); and (b) they discover a point where they can enter the house.
Any measures you take to eradicate the problem must focus on these two points.
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What Steps Can be Taken to Rid Your House of a Silverfish Infestation?
Most DIY methods of getting rid of silverfish will have a decent chance of succeeding only if the infestation is relatively small and confined to a few areas of the house. If there are rampant signs of silverfish damage and/or you spot them regularly, it may be time to call an exterminator.
Our recommendations below start with hygienic tips and natural, non-toxic remedies. We then escalate to chemical and toxic substances.
Caulk and Treat Entryways
Experts often recommend caulking entryways to your house and lining them with steel wool. In addition, putting in natural remedies such as diatomaceous earth will help contain and deter silverfish from coming in. This is a non-toxic material that irritate silverfish and other pests.
Use Cedar Oil
The smell of cedar oil keeps many pests away, including silverfish. Spraying or putting drops of cedar oil next to food sources, entryways and known spots where the insects have been spotted will help contain an infestation in its early stages. Beyond a certain point, it may not work quite as well.
Since silverfish cannot climb walls, there are some homemade traps that work well to trap the insects. For example, if you cover the outside of a jar with masking tape and put starch laden food items inside, silverfish will be attracted to the bait and likely get trapped inside.
A method like this will only work if the infestation is small, since there is a limit to the number of silverfish that will get attracted to the same bait within the same trap.
Use Chemical Deterrents
In the event of larger infestations, you could consider using chemicals that are toxic to silverfish and other pests, usually a mixture of substances such as boric acid, pyrethrins and pyrethroids, often punched in with sugary substances.
When you take the route of chemicals and toxins, you may consider consulting an exterminator. These items are toxic to humans (especially small children) and pets and should not be left lying around.
It is best to be extremely careful – for example, only place them in unvisited corners of the house, such as basements and attics.
Call an Exterminator
As mentioned initially, a large infestation of silverfish can become problematic in many regards, and it’s likely time to hit the reset button. Instead of flooding your house with toxic material, call a professional exterminator and let them advise you on how best to proceed.
Once you have managed to stem the tide, it is time to move on to the next step and figure out a way to stay free and clear of future silverfish infestations.
How to Avoid Silverfishes Coming Back?
The best way to prevent silverfish from coming back is to alter the friendly habitat and cut off sources of food. Look to improve the cleanliness in your house, as well as to find and eliminate areas which stay moist year-round. Vacuum regularly.
Run a dehumidifier in areas where silverfish have been spotted, including next to crawl spaces, attics, basements, laundry rooms, bathrooms and the like. Ensure that the ridge vents on your roof work, so that your house is able to sustain a drier environment inside. Check for signs of mold, wood rot and wall damage while you’re at it.
Do not leave food out. Instead, use air-tight, sealed containers for dry and wet food. Avoid leaving dirty dishes, open pet food bowls, damp clothes, old newspapers and magazines etc. lying around.
You may want to consider leaving some natural deterrents, such as cedar oil, in spots where you have had silverfish show up in the past – till such time as you are confident that they are gone.
In Conclusion …
A lone silverfish may well portend serious issues that could arise in the future, both in terms of the damage a colony could do and as a warning sign that you may be living in an unhealthy, dank environment which may compromise your health.
Taking steps to stop the infestation and then cleaning up and dehumidifying your house regularly will ensure a healthier lifestyle and get rid of the nuisance value of the pest. In an extreme case, an exterminator may be your only answer. Whatever your options, it is best not to ignore the sight of a silverfish.
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