Finding your first silverfish can be surprising.
Finding a second one usually leads to a different question.
“Why are they in my house?”
After helping homeowners identify silverfish for years, I’ve found that they almost never appear without a reason.
Unlike flies that wander inside through an open door or ants that follow food trails, silverfish are attracted by the conditions your home provides.
If they’re living in your house, they’re finding moisture, shelter, food, or all three.
The good news is that once you understand what’s attracting them, they’re usually much easier to eliminate for good.
The Short Answer
Silverfish are attracted to homes that provide:
- High humidity.
- Moisture from leaks or condensation.
- Dark hiding places.
- Paper, cardboard, or glue.
- Pantry foods rich in starch.
- Long undisturbed storage areas.
- Small cracks where they can hide.
Most silverfish infestations aren’t caused by poor housekeeping.
Instead, they’re usually the result of environmental conditions that make your home comfortable for them.
High Humidity Is the Number One Cause
If I had to point to one thing that attracts silverfish more than anything else, it would be humidity.
Silverfish lose moisture easily through their bodies, so they naturally seek places where the air stays damp.
That’s why they’re commonly found in:
- Bathrooms.
- Basements.
- Crawl spaces.
- Laundry rooms.
- Utility rooms.
Homes with consistently high indoor humidity almost always have a greater chance of developing silverfish problems than homes that stay dry.
Hidden Water Leaks Create Perfect Conditions
Sometimes the humidity isn’t obvious.
I’ve seen silverfish infestations caused by leaks homeowners didn’t even know existed.
Common sources include:
- Slow leaks beneath sinks.
- Dripping plumbing inside walls.
- Water around toilets.
- Condensation on cold water pipes.
- Roof leaks.
- Damp basement walls.
Even a small amount of constant moisture can create the environment silverfish need to survive and reproduce.
That’s one reason I always recommend checking for plumbing problems before focusing only on insecticides.
Cardboard Boxes Are One of Their Favorite Hiding Places
This surprises many homeowners.
Cardboard isn’t just a hiding place.
It’s also a food source.
Silverfish feed on starches used during the manufacturing process, along with glues and other organic materials found in cardboard.
If you’ve stored moving boxes in a basement or garage for several years, you’ve created an excellent home for silverfish.
Whenever possible, I recommend replacing cardboard storage boxes with sealed plastic totes.
That simple change removes both shelter and one of their preferred food sources.
Books, Paper, and Old Documents Attract Silverfish
Libraries, storage rooms, and closets are common places to find silverfish.
That’s because they love materials containing starch, cellulose, and glue.
Some of their favorite items include:
- Books.
- Magazines.
- Newspapers.
- Cardboard.
- Old photographs.
- Wallpaper.
- Wallpaper paste.
- Paper files.
If these materials are stored in damp locations, the problem becomes even worse.
That’s one reason silverfish are common in unfinished basements and long-term storage rooms.
Pantry Foods Can Also Attract Them
Silverfish don’t survive on paper alone.
They’re also attracted to many common pantry items.
Foods they may feed on include:
- Flour.
- Cereal.
- Oats.
- Pasta.
- Rice.
- Pet food.
- Baking mixes.
Fortunately, this is an easy problem to solve.
Storing dry foods in airtight containers dramatically reduces their access to these food sources while also helping protect against pantry pests in general.
Clutter Gives Silverfish More Places to Hide
One thing I notice in almost every silverfish infestation is an abundance of hiding places.
Silverfish don’t like open spaces.
They prefer areas where they can spend the entire day undisturbed before coming out to feed at night.
Some of their favorite hiding places include:
- Stacks of cardboard boxes.
- Old newspapers.
- Books stored for years.
- Closets packed with clothing.
- Storage rooms.
- Wall voids.
- Behind baseboards.
- Under large appliances.
The more clutter a room has, the easier it becomes for silverfish to avoid predators and establish a breeding population.
Cracks and Crevices Give Them Safe Shelter
Silverfish don’t need much space.
A tiny gap beneath a baseboard or around a plumbing pipe is often all they need.
Once inside these protected spaces, they’re difficult to reach and can remain hidden for months before homeowners realize there’s a problem.
Some of the most common entry and hiding locations include:
- Gaps beneath baseboards.
- Cracks around plumbing.
- Spaces beneath cabinets.
- Wall voids.
- Around window trim.
- Under flooring transitions.
While sealing these areas won’t eliminate an existing infestation, it can make your home much less inviting over time.
Silverfish Often Hitchhike Into Homes
Not every silverfish walks in from outside.
I’ve seen plenty of infestations start because the insects were accidentally brought indoors.
They commonly hitchhike inside:
- Cardboard moving boxes.
- Used books.
- Antique furniture.
- Thrift store purchases.
- Stored decorations.
- Boxes that have been sitting in garages or sheds.
If you’re bringing long-stored items into your home, it’s worth inspecting them first, especially if they’ve been kept somewhere damp.
Why Are Silverfish Suddenly Appearing?
A question I hear all the time is:
“I’ve lived here for years. Why am I just now seeing silverfish?”
Usually, one of two things has happened.
The population has slowly grown until it’s finally noticeable.
Or…
Something inside your home recently changed.
Common triggers include:
- A new plumbing leak.
- Rising humidity during the summer.
- Storing more cardboard or paper.
- Finishing a basement.
- Bringing infested items indoors.
Silverfish are nocturnal and excellent at hiding.
By the time you begin seeing them regularly, they’ve often been living in the home for quite a while.
How Do You Stop Attracting Silverfish?
The good news is that once you remove what they’re looking for, silverfish become much easier to control.
I recommend focusing on these areas first:
- Repair plumbing leaks.
- Run exhaust fans after showers.
- Use a dehumidifier in damp rooms.
- Store papers and keepsakes in sealed plastic containers.
- Replace cardboard storage boxes with plastic totes.
- Vacuum behind furniture and appliances regularly.
- Seal cracks around plumbing and baseboards.
Those changes make your home much less attractive to silverfish while also helping prevent many other moisture-loving pests.
The Best Way to Eliminate Silverfish Once They’re Inside
Reducing moisture is always the first step.
But if you’re already seeing silverfish regularly, you’ll usually need to treat the hidden areas where they’re living.
For active infestations, my top recommendation is the HARRIS Boric Acid Roach and Silverfish Killer Powder with Lure because it works inside the cracks, crevices, and wall voids where silverfish spend most of their lives.
I explain exactly how to use it, where to apply it, and why I recommend it in my guide to the Best Silverfish Killer That Actually Works.
If you’re looking for a non-spray option, I also recommend reading my guide on whether diatomaceous earth works for bugs. When used correctly in dry areas, it can be another effective tool for long-term silverfish control.
Frequently Asked Questions
Why do I suddenly have silverfish in my house?
Silverfish usually become noticeable because indoor humidity has increased, a hidden moisture problem has developed, or the population has grown large enough that you’re finally seeing them at night. Those same humid, concealed areas are worth checking when learning where silverfish eggs may be hidden.
Do silverfish mean my house is dirty?
No. Silverfish are much more strongly attracted to moisture, humidity, and hiding places than they are to general cleanliness. Even very clean homes can develop silverfish problems if conditions are favorable. Their preference for damp hiding places is separate from the question of whether silverfish are dangerous, which silverfish are much more strongly attracted explains.
Why are silverfish always in my bathroom?
Bathrooms provide everything silverfish like: moisture, warmth, darkness, and plenty of cracks and crevices to hide in. That’s why they’re one of the most common rooms where homeowners find them.
Will lowering humidity get rid of silverfish?
Lowering humidity won’t instantly eliminate an infestation, but it makes your home much less suitable for silverfish and is one of the most important long-term prevention steps.
Can silverfish come from cardboard boxes?
Yes. Silverfish can hide inside stored cardboard boxes, and they also feed on the starches and adhesives used to manufacture cardboard. That’s why replacing cardboard with sealed plastic storage containers is often recommended.
Silverfish Can Enter From Outside
Although many silverfish spend their entire lives indoors, they don’t always start there.
Some species naturally live outdoors beneath:
- Rocks.
- Tree bark.
- Mulch.
- Leaf litter.
- Around foundations.
From there, they can enter through surprisingly small openings.
Some of the most common entry points include:
- Gaps beneath exterior doors.
- Cracks in the foundation.
- Openings around utility pipes.
- Damaged weatherstripping.
- Window and door frames.
- Vents and crawl space openings.
Once inside, they usually settle wherever they find the combination of moisture, darkness, and food they’re looking for.
Does Finding One Silverfish Mean You Have an Infestation?
Not always.
An occasional silverfish can wander indoors from outside or emerge from a hiding place you’ve never noticed before.
If you’ve seen only one over several months, I wouldn’t immediately assume you have a serious problem.
However, if you’re seeing them:
- Every few nights.
- In multiple rooms.
- In different sizes.
- Around books, cardboard, or damp areas.
There’s a good chance more are hiding nearby.
Silverfish are nocturnal and excellent at staying out of sight, so seeing several usually means the population has already grown beyond just one or two insects.
My Advice
Whenever someone tells me they have silverfish, I don’t start by asking how many they’ve seen.
I ask two different questions instead.
“Where did you find them?”
and
“Why would they want to live there?”
Those two questions usually reveal the answer.
A humid bathroom.
A damp basement.
Old cardboard boxes in storage.
Books stacked in a closet.
A slow plumbing leak beneath a sink.
Silverfish aren’t randomly choosing your home.
They’re responding to conditions that make it an ideal place to survive.
Once you remove those conditions, getting rid of them becomes much easier.
If you’re already seeing silverfish regularly, I recommend treating the hidden areas where they’re living with the HARRIS Boric Acid Roach and Silverfish Killer Powder with Lure. I explain exactly where to apply it and why it’s my top recommendation in my guide to the Best Silverfish Killer That Actually Works.
At the same time, don’t overlook moisture control. If you’re looking for a non-spray option that can work well in dry cracks and voids, my article on whether diatomaceous earth works for bugs explains when it’s effective and when it isn’t.
About the Author
Mark Ellison is a structural pest management consultant with more than 20 years of experience helping homeowners solve indoor pest problems. He specializes in moisture-related pests and long-term prevention strategies that eliminate infestations by addressing the underlying cause instead of relying solely on insecticides.
