The tiny bugs people find in bathrooms are usually drain flies (small fuzzy flies near the sink or shower), silverfish (shiny, wriggling and wingless), springtails (dark specks that jump), or booklice (pale specks on damp surfaces). House centipedes, earwigs and the occasional cockroach from a drain round out the list. What they have in common is moisture, so the lasting fix is a drier bathroom and a clean drain, not a can of spray.
None of these bugs bite people, and none of them mean your home is dirty. They mean something is damp.
Which bathroom bug do you have? #
| What you see | Size | Probably | Where it lives | Harmful? |
|---|---|---|---|---|
| Small gray fuzzy flies resting on walls, wings folded like a roof | About 1/8 inch | Drain fly (moth fly) | Film inside sink, shower and tub drains | No |
| Silver, carrot-shaped, three tails, quick wriggle | About 1/2 inch | Silverfish | Behind tiles, under sinks, in cabinets | No, but eats paper and starch |
| Dark or gray specks that pop into the air | 1 to 2 mm | Springtails | Wet grout, window sills, houseplant soil | No |
| Pale tan specks, soft, slow | 1 to 2 mm | Booklice | Damp cardboard, moldy corners, toilet paper stock | No |
| Yellowish body, many long legs, very fast | 1 to 1.5 inch body | House centipede | Floor drains, basements, damp walls | No, eats other pests |
| Brown insect with pincers on the rear | About 1/2 to 3/4 inch | Earwig | Under bath mats, around tub edges | Can pinch, but harmless |
| Large reddish or black roach | 1 to 1.5 inches | American or Oriental cockroach | Coming up from drains and pipes | Contaminates surfaces |
Fuzzy little flies: drain flies #
Drain flies, also called moth flies, are the classic bathroom bug. They have short, hairy bodies and hairy wings held over the body like a pitched roof, so at rest they look like tiny gray moths. They flutter weakly and often sit on the wall near the shower or tub.
Their larvae live in the slimy film of hair, soap and bacteria that coats the inside of drains and overflow holes, and feed on it. The common household species don’t bite and aren’t known to carry disease.
Confirm the drain #
Put a strip of clear tape loosely over the drain opening before bed, sticky side down, and leave a gap so air can move. If flies are breeding there, you’ll find a few stuck to the underside in the morning. Check each drain, including the tub overflow and any floor drain.
Clean the film, not just the water #
- Remove the stopper or strainer and pull out any hair clog.
- Scrub inside the drain pipe as far as you can reach with a stiff pipe brush or drain snake. The goal is to break up the gel-like film where the larvae live.
- Flush with hot water, and repeat for several days.
- Clean the overflow opening on tubs and sinks, which is often forgotten.
Pouring bleach down the drain usually doesn’t work well on its own because it runs past the film instead of removing it. If flies keep appearing after a week of scrubbing, the source may be a drain you don’t use much (a guest shower, a basement floor drain) or a leak under the floor. That’s worth a plumber’s look.
Silver and wriggly: silverfish #
Silverfish are about half an inch long, shiny silver or pearl gray, with long antennae and three tail-like bristles. UC IPM says they thrive in damp, warm spots (roughly 71 to 90°F) and eat starches: flour, cereal, pet food, glue in paper and book bindings, and household dust. They can survive months without food, which is why a few hang on even in clean homes.
Their jaws are weak. They scrape the surface of paper rather than biting, and they don’t bite people.
What works: cut humidity with the exhaust fan and a dehumidifier, fix drips, clear out stored paper and cardboard from under the sink, and seal cracks along baseboards and around pipes. UC IPM lists crack-and-crevice insecticides and dusts as options if moisture control alone doesn’t do it.
Tiny specks that jump: springtails #
If a dark speck vanishes into the air when you touch it, it’s likely a springtail. Penn State Extension describes them as usually 1 to 2 mm long, in colors from white to black. They have a forked tail that can launch them up to 100 times their body length. They feed on mold, mildew, fungi and decaying plant material, not people.
They show up in bathrooms and basements, in new homes where walls are still drying out, and in overwatered houseplant soil. A lot of them indoors often follows a heavy rain or a long drought outside.
What works: dry things out. Penn State recommends air conditioning or a dehumidifier, removing mold, letting potted plant soil dry between waterings, and pulling thick mulch back from the foundation.
Pale, slow specks: booklice #
Booklice aren’t lice and don’t bite. Penn State describes them as 1 to 2 mm, soft-bodied, and tan, gray or nearly clear. They eat the microscopic mold that grows in humid spaces, so bathrooms without good ventilation, damp cardboard boxes and stored paper goods are prime spots. Getting humidity below 50% usually starves them out without any pesticide.
Many legs, very fast: house centipedes #
A house centipede darting across the floor at night is alarming but helpful. Penn State notes they eat silverfish, cockroaches, carpet beetle larvae and spiders, and like floor drains without water traps, concrete slabs and damp block walls. If you see them often, it usually means there’s both moisture and other bugs for them to eat. Read more in are house centipedes dangerous.
Cockroaches coming up the drain #
Big roaches in a bathroom are usually the American cockroach (about 1.5 inches, reddish brown) or the Oriental cockroach (about an inch, shiny black or dark brown). The University of Kentucky says Oriental cockroaches favor cool, damp places like sewers and crawlspaces, and American cockroaches like basements and damp areas.
Keep water in the traps of rarely used drains (run the tap once a week), fit drain covers, and seal the gaps where pipes go through walls and floors. The small, striped German cockroach is a kitchen pest; if you see those in a bathroom, check our guide to small brown bugs in the kitchen.
The real fix: a drier bathroom #
Every bug on this list depends on damp conditions. A few changes solve most cases:
- Run the exhaust fan during showers and for a good while after, or crack a window.
- Fix dripping taps, a sweating or running toilet, and leaks under the vanity.
- Re-caulk around the tub and shower so water can’t soak into the wall.
- Use a dehumidifier in bathrooms without a fan, aiming for below 50% humidity.
- Don’t store cardboard, paper towels in open packs, or old magazines under the sink.
- Clean drains and overflow holes every month or two.
Skip foggers. They don’t reach the cracks and drains where these bugs actually live.
Getting a positive ID #
Bathroom bugs are small, so the photo matters. Catch one on clear tape, set it on a white surface, and shoot as close as your phone can focus in bright light. Our bug photography guide explains what to capture.
Insect Identity will give you a name from that photo in about a second, offline and without uploading it anywhere. It recognizes the moth fly (drain fly), common silverfish, house centipede, common earwig, common fruit fly and the American, Oriental and German cockroach, and shows a confidence score with four runners-up. Springtails, booklice and firebrats aren’t among its 224 species, so a very small speck that scores low on everything is probably one of those. Use the table above to check.
Frequently asked questions #
Are drain flies harmful? #
The common household drain flies don’t bite or sting and aren’t considered a disease risk. They’re a nuisance and a sign of buildup in a drain. Large numbers can trigger allergies in some people, which is one more reason to clean the drain.
Why do I have silverfish in my bathroom even though it’s clean? #
Silverfish need humidity more than dirt. A bathroom that stays damp after showers, with gaps behind tiles or baseboards, suits them even if it’s spotless. Improving ventilation and sealing cracks does more than extra cleaning.
What are the tiny black bugs that jump in my bathroom? #
Almost certainly springtails. They’re harmless and feed on mold and mildew, and they mean there’s moisture somewhere, often in grout, around a window, or in a houseplant pot. Fleas also jump, but they’re usually found near pets and bedding, not bathroom tile.
Does bleach kill drain flies? #
Bleach can kill some larvae it touches, but it tends to flow straight past the slimy film they live in. Scrubbing the inside of the drain with a brush to physically remove that film is what stops the breeding.