Silverfish, centipedes and earwigs: what you found in the bathtub
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By John Stopka, Co-Founder & CEO · Reviewed by John Stopka
Three very different creatures turn up in bathtubs, sinks and basements at night, and people mix them up constantly: silverfish, house centipedes and earwigs. Telling them apart is the first job, because none of them is quite what people fear it is. The second thing worth knowing is what they share — all three are tied to damp — so finding one indoors is information about conditions in your home rather than a verdict on your housekeeping.
What is the bug in my bathtub or sink?
Start with the shape: each has one you can name from the doorway.
A silverfish is a wingless insect with a "flat, carrot-shaped" body [2] — silver-gray, tapering to fine bristles at the tail, wriggling rather than marching.
A house centipede is the one with the legs: about an inch long, with "grayish-brown to yellowish-brown bodies, three dark bands running down their bodies" and "up to 15 pairs of spindly banded legs" [1]. It is "the only species of centipede that can survive inside of structures" [1], so the long-legged sprinter on the bathroom wall is almost certainly that one.
An earwig is "dark, reddish-brown" and "easily identified by the pincer-like projections on the tip of the abdomen, called forceps" [3] — the pincers being the entire reason earwigs unsettle people.
Why do I keep finding silverfish in the bathroom?
Because the bathroom is usually the dampest room you own.
Silverfish "prefer damp and cool places, such as basements, attics, garages, laundry rooms, closets, and storage areas with boxes and/or books" [2], and they eat starch — "starchy substances like cotton, linen, silk, wallpaper, and glues used in book-bindings and cardboard boxes" [2]. The bathroom supplies the humidity; a cupboard of towels, boxes or paperbacks supplies dinner.
The National Pesticide Information Center states the diagnosis in one line: "The presence of silverfish or firebrats indicates too much moisture in the area" [2]. A silverfish is a humidity reading with legs.
Are house centipedes dangerous?
Not seriously, no.
House centipedes "pose a minimal bite hazard as their forcipules are so small, that it is difficult for them to successfully pierce human skin" [1].
Handling a larger centipede is a different matter. University of Kentucky entomologists write that centipedes "can inflict painful bites on humans when handled", adding that "this bite is unlikely to cause serious harm, especially from smaller centipede species" [1]. Illinois Extension is blunter — "If threatened, they may bite" [5] — so do not pick one up.
Earwigs are milder still: they "are not poisonous and generally will not bite or sting humans", though "they may pinch the skin with their forceps" [3].
If a bite or a pinch concerns you, contact a healthcare provider.
What is the difference between a centipede and a millipede?
Count the legs on one segment, then watch how it moves.
University of Kentucky puts it in the body plan: centipedes have "one pair (two legs total) per body segment", while millipedes have "two pairs on each body segment" [1]. Centipedes have "flattened bodies"; millipedes have "rounded bodies (most species)" [1].
Behaviour separates them just as well. "Millipedes are usually slower-moving compared to centipedes" [1], and a threatened millipede will "curl up tightly" [1] rather than run.
What they eat explains where you meet them. Centipedes are "generalist predators, feeding on a wide array of other invertebrates" [1], so they turn up where other insects already are. Millipedes "feed on decaying plant material and organic matter" [1], which keeps them in damp leaf litter, mulch and the edges of a crawlspace.
The last difference is the one people ask about. Centipedes have forcipules that "inject venom" and "can inflict painful bites on humans" [1]. Millipedes do not bite; they "secrete unpleasant-smelling fluids when threatened" [1]. If something has bitten you and it is bothering you, ask a healthcare provider.
What are pill bugs, and why are they in the house?
Pill bugs — roly-polies — are not insects at all. They are crustaceans, related to crayfish and shrimp, and they breathe through gill-like structures that only work when they stay damp. That one fact explains nearly everything about them.
A pill bug is gray, about a third of an inch long, with a curved, segmented shell, and it rolls into a tight ball when touched. The sow bug is its near twin: flatter, unable to roll up, with two small tail-like points at the back.
Outdoors they live under mulch, leaves, stones, boards and flowerpots, eating rotting plant material. They come inside by accident, usually under doors and through gaps near the ground, when it turns very wet or very dry outside.
They are harmless. They do not bite or sting, carry disease, or damage wood, food or fabric. Indoors they dry out and die quickly, so finding them in numbers points at a damp spot or a moist bed of mulch against the foundation right outside, not at an indoor population.
Do earwigs crawl into your ears?
Not in the way the folklore says. The name is the origin of the story: it "is thought to derive from an Old English word 'earwicg' that means 'ear creature' or 'ear beetle'" [4]. University of Kentucky's Jonathan Larson addresses the superstition directly, writing that "there have been instances where earwigs have been found in human ears, but they don't appear to seek them out for shelter, nor have they ever actually been recorded to consume brains" [4].
Earwigs are "most active at night and seek shelter during day" [3], which is why you meet one in the bathroom in the morning.
Where do silverfish come from?
They are already in the building — silverfish live their whole lives indoors in damp, undisturbed places: bathrooms, basements, laundry rooms, attics, wall voids, and the boxes, books and papers stored there. They arrive in cardboard boxes, old books and stored items, and they stay where humidity is high and there is starch to eat: paper, glue, wallpaper paste, cardboard and dry foods. Silverfish live for years and are active at night, so a few seen now and then usually means a steady population somewhere quiet and damp.
Why are there earwigs in my house, and do they bite?
Earwigs live outside under mulch, leaves, stones and boards, and they come inside when it turns very hot and dry or very wet, usually through gaps at ground level. Finding them in a bathroom, basement or kitchen usually means damp mulch or leaf litter right against the foundation.
They can pinch with the pincers at their rear if handled, but the pinch is weak and they do not bite people in any meaningful way. Earwigs indoors do not survive long and do not breed in the house.
What are booklice?
Tiny, pale, soft insects, about a sixteenth of an inch long, that run quickly across books, papers, shelves, windowsills and stored food. Despite the name, they are not lice and do not bite people or pets. Booklice feed on the microscopic mold that grows in humid places, so they turn up in new homes where building materials are still drying, in damp basements, and on old books and papers. Lowering the humidity — a dehumidifier, better airflow, fixing leaks — is what makes them disappear.
What are springtails?
Tiny, dark or grayish specks, often around sinks, tubs, floor drains, potted plants and basement floors, that jump when disturbed — a small spring folded under the body flips them into the air. Springtails live in damp soil, mulch and leaf litter, and they come in when the ground outside is saturated or very dry. They do not bite or damage anything. Like booklice, they are a moisture signal: they disappear when the damp spot does.
Does finding one mean my house is dirty?
No. It means something is damp, which is a different problem with a different fix.
None of the three is a filth pest. Centipedes and millipedes are "associated with damp, moist areas, found under rocks, leaf litter or mulch, or in the soil" [1]; earwigs "frequently enter the house and are often found in the basement or crawlspace" [3] from mulch outside; silverfish follow humidity and starch [2].
Most of what wanders in does not last: "Most millipedes and centipedes will die shortly after entering a structure due to the lack of moisture" [1]. An occasional one in the tub is traffic. A steady supply means conditions indoors are keeping them comfortable.
The damage is limited, too. Centipedes leave the house and its contents alone — "Stored food and other items in the home are not damaged" [5]. Silverfish are the exception: paper, glue and fabric are food to them [2].
What actually reduces them?
Drying first, then sealing.
NPIC's moisture list is short: "Repair leaking pipes, seeps, and eliminate standing water. Use fans to ventilate closed rooms, basements, and attics. Consider using a dehumidifier" [2].
Outside, the damp belt around the foundation feeds the traffic: "Moisture-collecting areas around a structure's foundation can often be resolved by removing or reducing mulch, woodpiles, or paving stones close to the home" [1]. Illinois Extension's earwig advice is the same — clear leaf litter, stones and mulch from the foundation, and keep shrubs trimmed [3]. Sealing gaps and cracks with caulk then closes the routes [1].
If the damp comes from under the house rather than the shower, that is a larger job than a bathroom fan — crawl space moisture is its own subject.
How does Liberty treat silverfish, centipedes and earwigs?
Silverfish, centipedes and earwigs are all covered by every Liberty pest control plan, so they are handled on the regular visits rather than quoted as a separate job.
Your Service Specialist applies a perimeter barrier around your home's foundation for crawling insects, to help keep centipedes from getting in.
They add granules in the landscape areas, where earwigs hide in mulch, leaf litter and flower beds.
The moisture side is part of the visit. They point out damp spots and leaks that draw silverfish and share tips to keep those rooms drier.
When to call a professional
Call when you are finding them steadily rather than occasionally, when they keep appearing after you have dried the obvious damp, or when you cannot find the moisture source.
An inspection settles what you have, where it is coming in and what is keeping it comfortable. All three are covered on a pest control plan, so treatment runs alongside the moisture advice rather than instead of it.
Common questions
What is the bug in my bathtub with lots of legs?
Almost certainly a house centipede: about an inch long, grayish-brown to yellowish-brown with three dark bands and up to 15 pairs of banded legs, and the only centipede that survives indoors [1].
Do earwigs really crawl into people's ears?
Earwigs have been found in human ears, but they do not appear to seek them out for shelter, and there is no record of them consuming brains [4]. The name comes from an Old English word meaning "ear creature" or "ear beetle" [4].
Does finding silverfish mean my house is dirty?
No. The presence of silverfish or firebrats indicates too much moisture in the area [2]. It is a humidity problem rather than a housekeeping one, which is why drying the room does more than cleaning it.
What is the difference between a centipede and a millipede?
Legs per segment. Centipedes have "one pair (two legs total) per body segment" and flattened bodies; millipedes have "two pairs on each body segment" and rounded ones [1]. Centipedes are predators that move quickly; millipedes are slower, eat decaying plant matter, and "curl up tightly when threatened" [1].
Do millipedes bite?
No. Millipedes "secrete unpleasant-smelling fluids when threatened" [1] rather than biting. Centipedes are the ones with venom-injecting forcipules that "can inflict painful bites on humans" [1].
Are pill bugs harmful?
No. Pill bugs are small crustaceans that eat decaying plant material. They do not bite, sting or damage the house, and indoors they dry out and die. Many of them inside usually means damp mulch or leaves against the foundation.
Where do silverfish come from?
They live indoors in damp, undisturbed places — bathrooms, basements, attics and stored boxes and books — and often arrive in cardboard boxes and old paper.
Do earwigs bite?
They can pinch with their rear pincers if handled, but it is weak and they do not bite people in any meaningful way.
What are booklice?
Tiny, pale insects that feed on mold in humid places — old books, papers, damp basements and new construction. They are not lice and do not bite.
Do pest control plans cover silverfish, centipedes and earwigs?
Yes. All three are covered by every Liberty pest control plan, so they are treated on the regular visits along with the other plan pests.
Sources
- University of Kentucky Entomology. Johnalyn Gordon, Jonathan L. Larson and Zach DeVries. "Centipedes & Millipedes in & Around the Home" (ENTFACT-645). https://entomology.mgcafe.uky.edu/ef645 (opens in a new tab)
- National Pesticide Information Center. "Silverfish and Firebrats". https://npic.orst.edu/pest/silverfish.html (opens in a new tab)
- University of Illinois Extension. "Earwig". https://extension.illinois.edu/insects/earwig (opens in a new tab)
- Kentucky Pest News. Jonathan L. Larson. "Earwigs: Hungry Bugs with Weird Butts". June 25, 2024. https://kentuckypestnews.wordpress.com/2024/06/25/earwigs-hungry-bugs-with-weird-butts/ (opens in a new tab)
- University of Illinois Extension. "Centipedes and Milipedes". https://extension.illinois.edu/insects/centipedes-and-milipedes (opens in a new tab)