Grout mites can be annoying because they’re hiding in your bathroom- a place that’s supposed to be clean.
But they’re making it dirty, stained, and grimy with their feces (poop) everywhere.
Gross. I thought showering was supposed to be cleansing?
They hide in the thousands of small holes found in grout while feeding on the microorganism that grow in them from your shower moisture.
Grout mites have no place in your home.
Even if they don’t damage your bathroom walls or tiles, they can still be a nuisance just seeing tiny bugs crawling all over the corners of your shower. Gross.
But don’t worry. They’re not that hard to get rid of.
In this guide, you’ll learn about:
- Why grout mites are in your bathroom
- Identifying grout mites from other psocids (pronounced: “SO- sids”)
- What they’re eating, where they’re hiding, and more
- How to get rid of them naturally without dangerous compounds
- How to prevent grout mites in the future
- And more
By the end of this page, you should have a solid foundation of knowledge to control, manage, and eliminate grout mites from your bathroom- for good.
Feel free to bookmark this guide as it’s quite detailed. You may want to refer to it later on!
If you have any questions about your infestation, just leave a comment at the end of this page and I’ll try to get back to you (as usual!).
There will be repeating themes throughout the guide- but that’s because it’s the same general basics to get rid of them.
It’s written so you can quickly jump to a particular section that deals with YOUR specific infestation without missing crucial details!
Sound good? Let’s send those grout mites to the grinder!
Last updated on: 4/25/22. Updated for accuracy.
What are the tiny bugs in my shower?
Well, check out this video to see a psocid in action:
Grout mites are in the same genus, so they’re pretty gross huh?
The ones in your shower aren’t booklice. They don’t necessarily eat cardboard, starch, or paper. But they can eat something you’d never expect- mold!
Your shower is wet. Your sink is wet. Wetness means mold or fungus. That’s where they hide. Get it now?
These are likely grout mites, also known as bird mites or rodent mites.
There are over 5500 identified species in the psocid group. They’re tiny, love moisture, and will feed on things you never expected (like books, starches, and even wallpaper).
What’s a grout mite?
Grout mites are very small, often ranging from 1-5mm in length. They can be brown, black, gray, or anything in between.
They also have very small wings that they use to get inside your bathroom, but not all of them may have a pair. Their mouths are powerful and let them break down organic matter like fungus, which often grows where grout mites hide.
These mites will often inhabit your bathroom or kitchen.
But they’re not limited to it- you may find grout mites in your garage, basement, or crawl spaces. Even your attic is a hiding place.
They just need some dirty mildew or fungus to grow. This is why keeping your shower clean, sealed, and in tip-top condition is key to keeping so many bugs out. Seriously.
You’d be surprised at all the bugs that thrive in these environments. Everything from:
- Oriental cockroaches
- German cockroaches
- Soil mites
- Fungus gnats
If they get into your food storage area, they can eat dry grains.
They may also hide under your sink if there’s leaking water. Don’t get them confused with booklice or drain flies, which are two different species.
The main difference is that grout mites are found in grout, which is usually in your shower tiles or kitchen. They like places that have mildew, which needs a warm humid environment to grow.
Without it, they won’t be able to sustain their numbers. Mold, mildew, fungus, and other nasty things are common in showers, especially if you have broken tiles.
They just collect water over time and this allows for their food source to grow easily. Dark, damp environments are their favorite.
Grout mites also like sweating pipes, as they produce condensation for mold spores to grow. As you can probably guess, controlling the humidity in their environment can eliminate these mites entirely.
If the humidity is low enough, they won’t infest your home.
Grout mites will infest food.
If you have stored food in paper, plastic, or even jars, they can get inside if it’s not sealed correctly. Since they’re small in size, they can squeeze into the smallest of cracks.
If you’ve ever looked carefully at a bag of chips that’s been sitting in your pantry opened weeks ago, it could have tiny little bugs crawling all over it.
Grout mites may also be called a variety of other names.
Because they’re so small, it’s hard for the casual homeowner to properly identify them.
Therefore, they have multiple names:
- Bark lice
- Psocids (technically correct)
- Bathroom mites
- Shower mites
- Moisture mites
- Mold mites
- Fungus mites
What do they look like?
Grout mites have small bodies with 6 legs.
They likely don’t have wings, but they can.
If you do see wings, they’ll be extremely small. While they usually don’t fly and can’t jump, they can run very quickly.
There’s a pair of antennas in the front.
They also have thicker legs in the back.
Armed with chewing mouthparts, they can chew through the toughest mold spores, damage wallpaper, books, and other soft materials that contain mold.
Grout mites vs. psocid
Grout mites are considered a psocid, which is a family of mites that comprises over 5500 species.
You may hear them referred to as psocids interchangeably.
Regardless, getting rid of psocid mite in your bathroom follows a careful approach of eliminating moisture, cleaning up infestations, and preventing future infestations.
Are they the same as moisture bugs?
Yes, they’re often interchanged with them because they’re so similar.
You can call them moisture bugs because that’s what they like- but it also includes other mites as well.
So if you’re talking to someone on the phone (like a pest control expert), don’t assume they’re moisture bugs.
Do they have wings?
Some do, some don’t.
If they’re indoor grout mites, they don’t have wings. They just have those plumb, wingless bodies with setae sticking out.
Even if they did have wings, it’d be hard to see without a close inspection. There are hundreds of different species, so they all have their unique features.
Do they jump?
Grout mites don’t jump but can fly if they have wings. They either have none or have very small wings that you can barely see.
So the answer is no, they probably can’t fly. If they do, they may be drain flies or fungus gnats.
They may have entered your home through the windows, cracks, or various crevices in your house through flight, or transported by some other creature.
Do they bite? Are they dangerous?
Grout mites don’t bite.
Although they have powerful mouths that let them break down scratches, book bindings, and even tile grout, they’re harmless towards humans. They also don’t bite.
While grout mites do feed on mildew or mold, it’s a low chance that they’ll transmit some pathogens to humans.
However, they can and will infest your food if given the chance, so be wary of that.
If you suspect a mite infestation in your pantry or other food storage, throw it out.
Other than causing the ugly stains on your bathroom surfaces, they can also release their long setae into the air. This will cause allergic reactions to sensitive individuals.
If you’re sensitive to contaminants, checking for grout mites may be something to be aware of.
What do they eat?
They eat mold, mildew, and fungus. This grows in dark humid places, such as broken tiles. So there’s no surprise that they’re in your bathroom.
Where do they come from?
Grout mites can fly, so they may enter your home through windows.
They’re also migratory and can enter through contaminated plants, grains, soil, or even your dirty shoes.
Birds can also carry them to your property, as they can cling to their feathers or infest the various bugs or insects birds eat.
Grout mites are common in states with high humidity, especially during the warmer months of the year.
These mites are hard to see, but once you see them all over your bathroom walls, then you know that grout mites are having a party, and you’re invited.
You’ll be dealing with the infestations for a few days but they should be easy to get rid of with some basic effort.
Signs of grout mites in your house
These mites are tiny so they’re not easy to see.
But there are some telltale signs you can look for to identify them so you can formulate a plan to get rid of them.
Here’s what to look for:
- Spots on your bathroom walls or tiles
- Brown or dark spots in the corners of your shower
- Brown or white “dust” on your cabinets, countertops, or food packaging
- White or tan wingless mites
- Stains on your shower tiles
- Moldy black spots near your windows
- Stinky odors that linger around your bathroom in specific areas
They hide in damp spaces where mildew or fungus grows. They love ductwork, baseboards, tiles, or sheetrock. All of these hold moisture for them to live in as they provide food for them to eat.
It doesn’t matter if your home is new or old- these mites will quickly infest your home if there are suitable environments for them to thrive.
Even a tiny patch of mold can be enough for thousands of them to sustain themselves.
Use a camera to get a good close-up view of them. Everyone has a smartphone nowadays. Use the zoom feature to spot those bugs!
Do they damage your shower?
Grout mites won’t damage your shower as they only feed on the mold or mildew growing on the grout. Other psocid mites may damage books, paper, or other starches.
Where do they hide?
They hide in dark, humid environments. In the bathroom, they’re likely behind tiles, baseboard, or the wall.
They can also be under your sink, in the cabinets, or around plumbing.
Grout mites often hide under a bathtub since it provides plenty of water if there’s a leak. It’s undisturbed.
Plus, leaky water gets pooled under there which builds up a lot of mold for them to eat.
Do they eat grout?
No, they don’t eat grout.
Grout is a hard, porous substance used to fill gaps.
Because of the thousands of tiny holes in it, it gives way for moisture to seep in and mold or fungus to grow.
Grout mites are also small enough to go into the many holes and cracks.
It’s like a playhouse for them- there are so many different tunnels for them to nest in, so it’s no surprise that grout mites love grout.
They don’t eat the grout- their chewing mouthparts aren’t nearly strong enough to break it down.
But they will eat the mildew or fungus that grows in the pores.
Over time, the grout will turn brown or black from some thousands of grout mites that inhabit it.
When are they active?
Grout mites are active 24/7. They come out during the warmer seasons and tend to show up in small numbers during the colder ones.
When it’s warm and humid out, they’ll have plenty of food to eat, breed, and nest in your home. Most people see mite activity during the June or July months of the year.
Grout mites may also come out in the spring.
But in the household, they can be present anytime since you have temperature control.
So don’t expect these pesky bugs to magically disappear on their own.
Are they hard to get rid of?
It depends. Is your bathroom in poor condition? Does it have leaks? Do you ever clean it?
The more neglected your bathroom is the likelihood of a serious mite infestation.
If your bathroom is in tip-top shape and you’re just noticing some staining on your tiles from these mites, then it’s very easy to clean up.
But if you’ve been lazy and put it off, then you’ll have a harder time getting rid of them. So like most answers- it depends.
Do they infest sinks?
Yes, they infest sinks that leak.
They’ll like to be under the sink, rather than in it. They’ll go wherever there’s moisture because that’s what gives them food.
Do you need a professional exterminator?
It depends. If you have allergies, don’t have time, or don’t know what you’re doing, then hiring a professional is worth it.
Sometimes you’ll spend so much time trying different things because you don’t want to pay someone.
Then you’ll hire someone when you give up, which basically ruins any money you saved because of all the time wasted, plus any DIY remedies you had to purchase.
So it’s always a gamble.
If you think you can do it, then, by all means, do it.
If you’re doubting yourself or you’re busy, just hire someone to take care of it for you. It saves you time, money and stress overall. I would know.
How to get rid of grout mites naturally
Here are some DIY home remedies to get rid of grout mites without using dangerous chemicals, powders, or sprays.
Depending on the extent of your infestation, you may find these techniques to be effective for minor to moderate grout mites. Try them out.
You just may save yourself the cost of hiring a professional if you can do it yourself.
Keeping the humidity low will kill the majority of grout mites in your bathroom. If you have a bathroom window, open it.
Keep the door open as well after your shower.
Remove all standing or excess water by drying it up.
Clean up after you use the sink.
Run fans or dehumidifiers in the bathroom to help drop the humidity.
If the humidity is constantly low, you can completely eradicate mites because it prevents the mold from growing. They also need humidity levels of at least 50% or so to breed.
Get a humidity monitor if you’re serious about getting them out. If you have a bathroom exhaust fan, use it!
The most overlooked solution, but most practical. Simply doing a thorough cleaning of your bathroom walls regularly will be enough to keep the mites to a minimum.
It may never fully get rid of them, but it should be enough to the point where they’re seemingly gone.
Remember that these are microscopic organisms, so their damage is only visible if there are a lot of them.
Start by cleaning your bathroom with natural ingredients:
Use vinegar to clean off calcium buildup
Sprinkle baking soda plus vinegar to make a powerful scrubbing solution to get rid of stubborn mold spores
Use 1 cup of borax with 1 gallon of water to clean grimy tiles
Dish soap can also be used when diluted with water for a quick cleaning solution that kills grout mites
For wooden cabinets or surfaces, use dish soap only if the finish is protected
Remove any mold-infested items such as rugs, clothing, blinds, towels, or other things that have spores or mites
Note: IF you have allergies, do NOT attempt to clean up the grout mites. They can cause allergic reactions. Hire a professional immediately. There could be a serious mold mite infestation in your house that requires professional work.
Increase the temperature
If your bathroom is always wet, consider turning up the heat in there.
This will evaporate the water quickly and dry out any grout mites that may be present. Lower humidity will kill the mites since they rely on a wet environment.
If you have bathroom heat lamps, heated tiles, or have a portable heat lamp, use them! Exercise safety precautions first.
Don’t use heated or electrical objects in areas they shouldn’t be used in.
Shut windows and doors when you do this to help increase the temperature.
Take shorter showers
Showering is the main contributor to high humidity in the bathroom.
Reduce your shower time to save water, lower your utility bill, and keep the mites away.
If you have a bad habit of running the water, consider taking cold showers.
They have their own set of benefits.
This may be obvious, but it has a huge impact on the humidity levels.
Cutting showering time in half makes it easier for the standing water to evaporate.
Replace old towels or bathroom rugs
Those decorative towels you have hanging there? Throw them into the wash.
The laundry will kill the grout mites in a single load. Towels, clothes, carpeting- they’re all perfect homes for mold spores.
Anything that’s fabric provides tons of surface area for mold to grow.
With that, you’ll get mites. Wash them regularly if you haven’t been doing so.
Get rid of hiding places
Grout mites like to hide in cracks that contain nice warm moisture for them to eat in peace. This is why tiles in your bathroom or kitchen are perfect environments for them.
They eat the mold or fungus that grows in these cracks, plus any other food sources like insects, starches, or grains. If you fix up these tiny cracks where moisture seeps into, then you don’t have a bug problem.
Without anywhere to hide and feed, they wouldn’t be in your house in the first place. Fix the root problem- the cracks or crevices scattered around your property!
It starts with going around your home to do a complete inspection, then fixing issues:
- Fix leaks under the sink
- Fix plumbing issues in the attic, behind walls, garage, etc.
- Dispose of old cardboard, books, papers, magazines, newspapers
- Replace any damaged or broken tiles
- Make sure your tiles aren’t peeling or coming loose
- Cracked tiles should be sealed or replaced
- Ensure all drainage systems are working
- Check for wood mold
- Keep your garden clutter-free
- Fix leaks in your faucets or showerheads completely
- Fix leaks in the roof or ceiling
- Run the AC more often if possible if you’re located somewhere with high moisture content
- Use fans or air circulators on dry days
- Keep vents clear
Keep drains clear
If you have backed up drains or water that drains slowly, fix it.
These are harbors for standing water. They should be free of grime, sludge, debris, and other nasty things.
If your drains are clogged or drain very slowly, this can bring in drain mites, pillbugs, silverfish, roaches, spiders, ants, and even scorpions!
Try boric acid
Get some pure boric acid and sprinkle it around your bathroom or wherever grout mites are present. The fine white powder pierces their outer shell and dehydrates them.
Since they rely on water, they’ll slowly leak it out over time because they can’t contain the water in their bodies. Boric acid can be purchased for cheap in bulk at hardware stores.
Apply it anywhere you suspect the mites to be hiding. Keep pets and people out of the area until the mites are gone.
Read the label before use. Make sure it’s pure boric acid.
Since it’s a fine powder, you can easily get it into edges or under baseboards so the mites come into contact with it.
It’s also good to toss some between cracks in the grout, which may contain moisture behind the tiles.
If you have these grout mites coming out of your bathroom shower or tiles in a wet, humid environment, there’s a bountiful supply of water for them to drink.
The boric acid soaks up some of it, but if you keep showering or getting the room wet, it will lose effectiveness.
So keep that in mind when you do this.
Or maybe borax
If you don’t have boric acid, substitute borax in place of it.
While not as effective in my opinion, it can still do the trick if you apply it correctly. Borax is also more widely available because you find it in superstores (look in the laundry aisle).
Sprinkle it where grout mites are hiding (between cracks, tiles, etc.). Read the labels before use. Use as directed.
Use organic diatomaceous earth (DE)
Another dehydrating powder, you can sprinkle organic, food-grade diatomaceous earth to help dry up the bathroom.
Take a small amount and lightly sprinkle over infestation sites. It works similar to borax or boric acid in terms of effectiveness.
Food-grade DE is safe for use, as it’s a consumable by itself. If you’re looking for a safer option, DE is a good choice.
Vacuum your bathroom regularly
Get into the practice of vacuuming your bathroom daily.
This helps get rid of dead mites and other mold spores from forming on the bathroom tiles.
If you have a hose attachment or portable vac, use it to vacuum the harder-to-reach areas like your cabinets, window, or wall tiles.
Keep it dry always
Grout mites like to hide where there’s a bountiful supply of water for them to drink, breed and eat.
Keeping the area dry will help evaporate stagnant water, which can keep the population that’s sustainable to a lower number.
Think about it: If there’s only so much water for them to utilize, once you dry it up, they have nowhere to hide. This is why you must keep the area as dry as possible.
No matter if it’s your kitchen, attic, walls, or your bathroom, grout mites only need a constant supply of moisture to thrive.
Do the following basic practices to minimize grout mites in the house:
- Wipe up any spills
- Keep your bathroom window open
- Evaporate any still water
- Repair, patch, or replace any damaged tiles
- Don’t get water in cracks
- Keep kitchen cabinets clean around the sink
- Check for leaks under the sinks of your bathroom or kitchen
- Inspect tile walls for leaks
- Inspect under bathtubs for fungus or mildew
- Check gutters or downspouts for blockage
- Check crawl space vents, which should be open when the weather is warm to reduce moisture
- Inspect for leaks behind walls or above the ceiling
- Check around baseboards for leaks
- Use a dehumidifier in wet areas
- Use a fan to help dry out your bathroom when it’s wet after showering
- Replace peeling paint or wallpaper
- Have a professional leak detector do a thorough inspection or use a leak detection tool to DIY
Don’t hesitate to hire a professional to do it for you
If your home is in a state of disrepair, consider hiring someone to help inspect and fix up your house.
Sometimes, it’s not worth the time or effort to DIY if you don’t know what you’re doing.
Don’t hesitate to resort to professionals for home repairs. It’s all about weighing your time vs. money.
If you do decide to hire someone, make sure they’re licensed, insured, and have good reviews/testimonials
You can start by doing a search for home repair companies near you. Get on the computer or pull out the phone book. Your call.
Call up some businesses (locally if possible). Get some quotes. See if they have discounts going on. Since it’s off-season (at the time of this writing), it may be cheaper.
The off-season for mites is generally in the fall to late winter.
This is when mites are least active in the household and when most people don’t complain about them- until spring comes around. Then it’s crazy.
Preventing grout mites permanently
Once you get rid of the mites once, you’ll quickly learn that you never wanna deal with them again.
Here are some excellent, simple tips to stop mites from infesting your bathroom for good.
Keeping your home adequately ventilated
Moisture buildup inside the home is the number one reason you get grout mites.
If your home is adequately ventilated at all times, then there will be limited mold colonies.
Even if you have a lot of spores coming in from the outside (pollen, allergens, then whole shebang), you can prevent them from growing inside on surfaces by keeping humidity in check.
Use fans, dehumidifiers, prop your doors or windows ajar, or install exhaust fans if necessary for rooms that are consistently humid.
If your home is already equipped exhaust fans (whether on the roof or window), use them!
Regular cleaning, vacuuming, laundering, etc. of your bathroom is a necessity if you want to keep it free of bugs.
You should be doing this on a weekly schedule to keep things going smoothly. It also makes it super easy to monitor the bug situation.
If you see fewer mites over time, then whatever DIY remedy you’re doing is working.
If not, then it’s time to assess the situation.
Check for infestations
Regularly check for bug infestations in your bathroom, especially near sinks, drains, and cabinets. These areas are bugs’ favorites.
If you start to see some dark spots forming around your bathroom in these key areas, including the tiles of your shower, baseboards, or ceiling, then it’s time to do a thorough inspection.
Clean it up while you check at the same time- it’s efficient.
Get a mold inspection
If you’ve had a prior grout mite problem, there may be a mold problem in your house. It can be behind the walls, up in the ceiling, or in the corners of your bathroom.
Getting a mold inspection can target the exact location of these spores, which can help eliminate the pest problem for good.
Consider hiring a professional mold inspector to give your house a complete inspection once a year if your property fits the image.
You may find these resources helpful:
- Booklice – Home and Garden IPM from Cooperative Extension
- Psocids (barklice, booklice) – UMN Extension
- [PDF] Psocid and mite pests of stored commodities
Did you get rid of the grout mites in your shower?
You know all the basics now, so you should have a good understanding of how to control, manage, and eradicate those pesky mites in your shower.
Getting rid of their living spaces is key to completely drive them out.
If you don’t repair or seal the grout, then they have somewhere to hide and eat a constant supply of mold growing from the shower moisture.
If you can effectively seal the damaged tile, then you’ll get rid of them for good.
Do you have any questions regarding your specific pest infestation? Feel free to drop them below and leave a comment.
Or if you found this guide helpful or have any feedback, please let me know as well. Consider telling a friend or your online communities that may get some value out of this page.
Thanks for reading.
Currently an active researcher in the pest control industry for the past 8 years- with a focus on using natural and organic methods to eliminate pest problems.
I share handy DIY pest techniques I come across here to help out others (and possibly save them from a mental breakdown).
Fight nature with nature.