Yes, silverfish can climb walls. They move up vertical surfaces like drywall, brick, wood, and concrete with little difficulty. The one thing they can’t climb is a smooth, glossy surface, which is exactly why you’ve probably spotted one trapped in your bathtub or sink.
What Silverfish Can and Can’t Climb
Silverfish grip surfaces using tiny structures on their feet that catch on microscopic texture. Any wall with even a slight roughness gives them enough traction to walk straight up. That includes painted drywall, wallpaper, bare wood, brick, concrete block, and textured tile. Their vertical speed is slower than their horizontal scurrying, but they’re still quick enough to disappear up a wall and into a ceiling crack before you can react.
Glazed porcelain, smooth enamel, and glass are a different story. These surfaces offer nothing for their feet to latch onto. A silverfish that wanders over the rim of a bathtub or porcelain sink will slide to the bottom and run laps for hours without making it back up. This limitation is so reliable that it’s the basis for a simple homemade trap: wrap a glass jar in masking tape, drop a piece of bread or rolled oats inside, and set it where you’ve seen activity. Silverfish climb the textured tape on the outside but can’t escape the slick glass interior.
Where They Go Once They’re on Your Walls
Silverfish are flat-bodied insects, thin enough to slip behind electrical outlets, light fixtures, and baseboards. Once they climb a wall, they typically disappear into wall voids, ceiling gaps, or cracks in trim where they spend the day hiding. They’re nocturnal, so the climbing mostly happens after dark when they leave these hiding spots to search for food and moisture.
Their preferred hiding spots share one thing in common: humidity. Silverfish thrive at 75% relative humidity or above and prefer temperatures between 72 and 81°F. They become stressed when humidity drops below 75% and start dying below 50%. That’s why they’re most often found in bathrooms, basements, laundry rooms, and kitchens, and why they gravitate toward pipes and plumbing gaps inside walls. A damp wall cavity is ideal silverfish habitat.
Why You Find Them in High Places
If you’ve found silverfish on your ceiling, in an upstairs closet, or inside a book on a high shelf, their climbing ability explains how they got there. They travel through wall voids vertically, moving between floors of a house through gaps around pipes, wiring, and ductwork. A silverfish that enters your home at ground level through a foundation crack can easily reach a second-floor bathroom by traveling inside the walls.
They’re also attracted to paper, glue, and starch, so bookshelves, cardboard boxes in closets, and wallpaper paste all draw them upward. Finding silverfish in elevated areas doesn’t mean you have a separate infestation up there. It usually means they’re traveling from a moisture source lower in the house.
Keeping Silverfish Off Your Walls
Since silverfish climb walls primarily to access hiding spots and moisture, the most effective approach targets both entry points and humidity. Seal cracks and gaps around baseboards, window frames, electrical outlets, light fixtures, and plumbing penetrations. Their flat bodies fit through surprisingly narrow openings, so caulk or foam any gap you can see.
Reducing indoor humidity below 60% makes your home far less hospitable. A bathroom exhaust fan that actually runs during and after showers, a dehumidifier in the basement, and fixing any leaking pipes will do more long-term good than most sprays. In rooms where you’ve seen silverfish, check for condensation on walls or pipes, as that’s often the moisture source drawing them in.
Insecticide barrier treatments applied along baseboards, window frames, and doorways can intercept silverfish as they travel across surfaces. These create a chemical zone that silverfish cross on their way to and from hiding spots. Sticky traps placed along walls in dark, humid areas help you monitor whether a population is growing or shrinking, even if they won’t eliminate an infestation on their own.
Storing paper goods, old books, and cardboard boxes in sealed plastic bins removes both food sources and hiding places. Silverfish eat the starch in paper, book bindings, and cardboard glue, so open storage in a damp basement is essentially an invitation.