How to Get Rid of Drain Flies: Fly the Larvae Down the Drain!

Edited by
Inga Cryton
Reading Time: 21 minutes.
Updated: .

Drain flies are also known as moth as they remind us of them by their size. They can be met in drains and other premises with high humidity.

When a few, they can be even useful as they remove clogs. But they breed very fast and it is dangerous for people’s health.

What is a Drain Fly?

A drain fly’s body is covered with fluff and their wings are hairy. They live up to a month. They have a very short period of life but they multiply extremely fast.

A mature female fly lays eggs in damp area and larvae pip out of them. Drain fly larvae are very resistant to temperature changes and they are able to survive in oxygen-poor conditions. Larvae pupate in drains and their wings appear as well.

While fighting with drain flies, destroy the breeding ground first.

After destroying the breeding ground, the reproductive process is broken. Clean the drains thoroughly, remove all the leaks. If you have difficulties with drain flies killing, get in touch with a professional team to help you solve the problem.

One couple of flies can procreate about 1 million units within 6-8 weeks.
33 million of bacteria live in a fly’s gut as well as half a billion more cover its legs and body.

Why Sewer Flies Are Dangerous?

More than a hundred bacteria are connected with flies which include salmonella, staphylococcus, dysentery, and colibacilli. These bacteria can cause such human diseases as enteric fever, cholera, dysentery, hepatitis, conjunctivitis, poliomyelitis, tuberculosis, etc.

Sanitary is the main aspect of drain flies fight but correct diagnostics is also important.

Small Drain Flies in Bathroom

Small flies in your bathroomHaving 2-3 mm flies in bathroom is a signal that your drain pipe is leaking.

The first step to remove the flies is to find the leakage. It can be under your sink, bath (if in the bathroom) or in the kitchen. Usually, the place is covered with larvae which produce these insects.

As soon as you find the leakage, destroy the breeding place and fix the leakage. These insects do not live in dry clean space.

Drain flies usually settle in leaking pipes.

You can prevent drain flies by:

  • Keep drain pipes clean and fixed.
  • Check regularly for any disorders.
  • Disinfect your sewer pipes with special means.
  • Keep an eye on drain clogs and remove them in time.
  • Keep reservoirs with water closed.
  • Don’t leave water in watering tanks.
  • If you live in a cottage, create an artificial pond with fish eating insects.

How to Kill Drain Flies

Chemical agents for insects destructionFighting with flies includes two basic methods:

  1. Fumigation: is a pest control measure which means poisoning them with toxic aerosols, gases, and vapors.
    To kill flies smoke bombs are often used with tightly closed windows and doors.
  2. Disinfestation: is a set of measures for the destruction of insects using biological and chemical agents.
    Flies removal involves treating various premises and major breeding sites of flies.

Each of them is effective but has its own peculiarities which you have to consider. We’ll try to explain it.

Home Remedy

Eliminate Sewer Flies in Your HouseScience provides us with all sorts of home fighting methods used to kill gnats, larvae, moth and drain flies. What you should remember that not all of them are healthy for humans. Fighting flies in domestic conditions is carried out by means of plates, liquids, and spirals from flies and gnats.

In order to prevent the spread of drain flies, it is necessary to observe sanitary rules and regulations.

To do this, take out the rubbish daily, install devices that will prevent the intrusion of flies into the room, and keep the room clean.



  • Before using a spray remember to keep your mouth covered with a mask.
  • Always put on gloves and long-sleeved clothes to protect your skin.
  • Wash your hands thoroughly after the disinfection.
  • Air the room (if it’s possible).
  • Remember to keep your children and pets out.

Microencapsulated Substances

For extermination of flies in premises microencapsulated funds are used. Such means minimize the risk of a negative impact on human health.

Microencapsulated substances give a good result because they have a long period of exposure. They have no odor, and after using them do not leave streaks and spots.

The effectiveness of the fight with insects depends on destroying breeding places of flies.

Destruction of larvae in drains.Therefore, the destruction of larvae in drains can lead to complete disappearance of flies.

Massive breeding places of flies need to be treated with means of acute exposure, with a characteristic pungent odor. The places are then treated with long-term prophylactic substances of drugs that have no smell.

This is necessary to prevent the re-emergence of insects.

Professional Control

Many modern disinfection remedy methods can help solve the problem of killing drain flies and gnats at home. But if it turns into a massive case, then you will need the experts’ help.

Real professionals know the specifics of every fly species that is why they use the most effective insecticides for killing particular insect species. And it should be noted that it gives visible results.

Preparing the Room for Disinfestation

To quickly get rid of flies, it is necessary to prepare the room, where the disinfestation will be held.

  • you need to hide all the food and personal care products (in the kitchen or bathroom);
  • free the access to the walls and the main landing sites of flies;
  • it may require the suspension of the room usage. Though this is applied to large rooms. Because in addition to powders the process may require a large amount of aerosol, after which you will need some ventilation.

After the Disinfestation

  • If your kitchen drain pipe was the reason, remember to wash the dishes and cutlery. Clean the tables, chairs and other furniture in the room.
  • Air the room thoroughly and it can be used again in a couple of hours.
  • Don’t wash the walls and other surfaces during several days.
  • Keep clean after the procedure and check for drain leaks.

You can find further details of Drain Flies Control here.

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  1. what are the products for destroying drain flies? Where and how can I buy locally or by mail?


    • what are chemicals to kill sewer flies in tolet bowl pipes? Where can I buy them?

      • What product is used to kill sewer mites in the bathroom??

        • I have to share this because I have had drain flies for the past two years that I bought and lived in my nEw home. I feel like I have tried everything: Vinegar and baking soda, bleach, pest control companies have poured “who knows what” chemicals down my drain and finally three months ago I paid a plumbing company to clean out my drains. But the flies were still there for weeks and months after. The plumbing guy suggested I cover the drain with a cloth and pour bleach slowly over the cloth and leave it there to allow the bleach to seep down the drain slowly. For the last three month I have had a cloth covering the drain and poured bleach on the rag twice, filled the area with water (so that the bleach could seep through the rag slowly). The flies are finally gone!!! Gone!!!! I am not sure if cleaning out the drains helped but I definitely believe that having the rag cover the drain for months with the occasional bleach and water being poured on top has done the trick. And I had to share so anyone who reads this so they can benefit from my experience. Finally!! Those bugs just wouldn’t go away with anything I have tried until now. Finally free!

          • Ty I have drain fly’s and they are annoying i can’t stand it i will try this!

          • Do you use the bleach straight or do you dilute it? thank you for this advice.

          • I worked in restaurant facilities and at first sight of drain flies we were told to pour bleach in the drains and to do it periodically thereafter to keep them from coming back.



    • Spray DW40 on the sides of the drain and into its bottom directly. Within 2 days your problems will be over with drain flies.

      • Omg!! This stopped them in their tracks! It instantly killed the ones on windows! I even went outside and sprayed a ton of it all over spot where I had sump pump drainage problem and the soil is still really water logged. Not sure how well that will work but can’t hurt to try til I get to store for something stronger. Plan on digging that area this fall when it dries out and putting cement down for next year. A million times thank u for posting this. I feel like I have been in a war zone at home for 2 weeks and hated using raid all time as bad to breathe. House smells like Wd40 right now but I will take that over the flies. Hopefully it will help longer than raid.

        • Another thing I forgot is I used generic Wd40 so very cheap help.

      • After doing the soda, vinegar hot water there were no change except the mouldy smell seem to have finally gone. Even tried out the tape over the sink but saw nothing but these wretched flies continued to appear. Decided to try the wd40 after reading you comment and can say that the wd40 worked for me. Sprayed in crevices along skirting panels where there are gaps around sink areas and floor then followed by fly spray in the air around the room close doors and windows, follow instructions on fly spray can, day 2 saw 1 in the morning, waiting for evening when the lights go on as they tend to appear in the evenings mostly. Repeated the spray and wd40 again though and the soda vinegar hot water down the toilet for the first time as 2 appeared in the toilet. Eventually they will have no place to hide. Wd40

    • Pour pine oil or pineSol down your drain

  2. I have a fly infestation in my bathroom and they are mostly in the shower cubicle. After many attempts of using drain cleaner they are still present. I cannot get to the drain as it is under a tiled bathroom floor so have just used gels and foam cleaner. I would be gratfull if you have any sugestions on how to clear them.

    • they nest in the YUK junk inside the drains like hair buildup and others items that are stuck in your drains. You need to get that junk OUT (not snake it down further) -then using a pipe brush clean as far as the brush will reach. Then, once the drain has been cleared of all debris possible-then you pour the GEL drano type of product. Im unsure how you are able to use the gels and foams you mention if you can not access your drain cover, another quick fix to clean out the drain pipes adequately would be to use a vinegar baking soda mixture poured down the drain.
      I know in my experience if they were in the shower cubicle then they are in the bathroom sink as well. I found most of them and their larvae etc in the top hole thing in my sink(think its to prevent sink from flowing over if filled to high?) Bleach didn’t kill the larvae, they managed to crawl up out of the sink and onto the counter after I WAS SURE THEY WERE DEAD-unpleasant to say the least. Again drain pipes must be clean to get rid of them as they breed in the organic matter that lives in and on the sides of the pipes. You may want to try a type of enzyme killing organic type gel available at most hardware stores. Without drain access that may be your best option at cleaning out most of the organic yuk rotting in the drain.

      • I have had problems with those tiny little black speck bugs in my bathrooms and kitchens in both Phoenix and Flagstaff for months. I tried everything. Professional fumigations, bug spray, bleach. Nothing worked.
        FINALLY, my husband brought home from work some of the bottled alcohol stuff for rubbing on hands to keep off germs on your hands! Voila! I took that and generously rubbed it all over my sinks, countertops, and even in the little hole in the bathroom sink to let excess water escape. DO NOT WASH OFF. JUST LET IT STAY THERE!
        No more bugs!
        They are GONE! I do it every day. Just smear the alcohol-based hand wash around and it either kills the larvae and/or the bugs but what a relief!

        Good Luck!

        • Did you have larvae and flies on your kitchen ceiling? That’s what IM DEALING WITH and can’t figure out what they are and how they got here. Have gone through all food so that’s not it. Checking the sink next.

        • Do you mean the real alcohol or the hand sanatizer?

          • Very helpful information. Thank you Do you mean the real alcohol or hand sanitizer?

            • have drain mites. how can I get rid of them permanently?
              Killed them once b ut they were back in 2 weeks.
              Where can I buy the correct chemicals?

              • I have the same problem. they were gone for 1 wk then returned. using vinegar jars but not eliminating . NEED HELP !

        • Are u talking about hand sanitizer

        • I tried it and it worked the first day. I even put the hand sanitizer down the drain. I’m going to treat my bathroom sink for a couple of weeks, and hope I’m rid of them permanently. Thank- you so much!!!

  3. If u have the flys in bath room u most likely have a leak somewhere. If u do not see the leak then it most likely is underground

  4. I am a painter and while on an estimate I noticed sewer flies. The owner stated that they have treated the drains but it takes some time for the problem to be taken care of. I am concerned that if I take this job I can bring them home with me. Is this a valid concern?

  5. I have some sort of tiny fleas crawling up one wall and lodge into the extreme corner of the same wall in my bathroom. Though I used all kinds of pest control, like Heat spray, kerosene, etc. these insects repeat their process up the same wall. At times I have found same insects under the plastic bucket and mug when dry. As suggested above, can I now use Baygon spray or liquid put into the drains of bathroom, sink, toilet. Please confirm or advise alternative treatment. Thnks.

  6. To kill,at least bring them down, the flies i simply spray them with soap water with spayer.but they root of the problem is the larvae coz they seems brreeding faster than the ones i kill,i need to work it out

  7. I see one of these flies once in a blue moon in a bathroom. Is that a “problem” or just a random fly that got in? We do have a septic tank right outside the bathroom where they are seen and I do use a product to biodegrade the contents of the septic tank. Now, growing up we had tons of these flies in our basement which happens to be where my room was. Should I be concerned? I also have been diagnosed with fibromyalgia not long after I moved out of my childhood home. Thanks for any advice or help.

  8. The septic tank was cleaned and the lid not properly put back on – we found after calling because the outside of our home, which is near the lid is covered with drain files. The guy fixed the lid, but as soon as he opened it all you saw was drain flies. Everything tells how to get rid of them in the drains and in your house – -what do I put in my septic tank to stop them from breeding. If you go out and kick the lid – out they come. HELP

  9. I have drain flies on the outside of my house , they just get all over the walls and doors and when you open the door they fly into the house. They get very annoying inside as they become quite lively at night and dive bomb into your face. We do have a septic tank in the front yard and also a large city storm drain. Please advise, I would appreciate your help. My exterminator sprayed the outside walls, but this didn’t seem to help much. Thank you

    • We are infested with drain flies and also have a septic system. Even spent 600 dollars to replace A laundry room drain..think their in the walls of a room on a slab.. Going in and out of my windows. Camera on our septic line shows cracks but everyone says there not bad… We have had plumbers contractors and insect control but no solutions. Can they be in the soil under our home?

  10. Ecosmart Organic Home Pest Control will actually kill the larvae.
    It is made of 2-Phenethyl Propionate, which is the only ingredient on the label that sounds like it is a chemical to read up on. The rest of the ingredients are essential oils which are OK but the smell will get to you eventually. From what I read you might have to treat the area for up to 3 weeks and from my experience that is the case. You have to keep applying this in places where the larvae grow like in the gaps of your tile grout. I tried everything and the tiny larvae seem to be immune to chemicals. I had one in a bucket and it was submersed in Mr. Clean for 3 days and it was still active and moving as much as the first day. I tried bleach, ammonia and other safer products but they did not work. They get the larvae to come out but they do not die and eventually go back and continue growing. Only Ecosmart actually drove them out of the crevices and they died.
    The flies eventually stop coming and then the larvae all die out. If you see a fly after 1-2 weeks of treatment, you are missing something. Find where they are emerging from.
    Good Luck

    • First of all, you probably know this already but never, ever allow bleach and ammonia to mix together!! It will create VERY toxic fumes that will destroy the lungs, and people have died from this.

      I had found these horrid little worm-like larvae in my bathroom sink and in my kitchen sink. I wasn’t even aware of the ones in my kitchen until one was somehow transferred from the sink into my cats’ water bowl! Yuck! I was so upset by this.

      Well, they seem to be impervious to nearly everything chemical. (I DO like Dave’s advice, below, re: WD40.) Anyway, one “worm” was in a lid in my kitchen sink. I poured blue Dawn on it (the formaldehyde in Dawn will kill a flea instantly,) I poured Lysol into the lid, and I also covered the creature with salt!! Made no difference.

      They cannot survive mechanical action: being squished – but who wants to do that? I then thought of something else they probably couldn’t survive: boiling water. It killed the one that was in the lid. I then poured some boiling water down every drain in my house, and continue to do this every few days. Have seen no more evidence of them.

  11. I just got introduced to these drain flies a month ago when I saw them on the walls of my apartment but with me the most of them were by the sliding doors in my living room and my bedroom. They are such nasty things and when you kill them they leave a black smudge. I live in a city and didn’t think there were these types of bugs here. The pest control people came in and sprayed the cupboards under my sink, I am not sure why that would help? and all I can smell is what they sprayed and I can’t open my windows to air out the smell. He said that I needed to keep all my windows and doors shut so I assume they thought that they were getting in that way.

    • This is my third year fighting drain flies. I have tried in-vade bio drain. did not help. since I have tried a combination of salt, baking soda and white vinegar I have almost won the battle.Now I only see one or two at a time. prior to this treatment there were many more. In as much as I have not won the war, I feel I am winning the battle. can not find the source, however. I will continue to use this treatment and now add mineral oil to the drains. good luck let me know how you all make out

  12. I have found an easy way to kill any type of insect from ants to flies to roaches – Anything.
    WD-40. WD-40 works by displacing water. Basically it sticks and spreads faster and better than water.
    I know it sounds crazy until you understand how small insects breathe.They don’t have lungs, they “breathe” by passive oxygen/CO2 exchange thru small holes on their legs & abdomen. If they get something like WD-40 on them they automatically try & clean it off & spread it around & onto these holes & it blocks oxygen exchange & they suffocate. If the insects are in your drains, cram a dry cloth towel down & then pull it back up & repeat until it is mostly dry. Use a white one that you can bleach. Then spray down LOTS of WD-40. Leave it alone (no water) for a couple of days. No worrying about toxic chemicals. Works like a charm.

  13. Sewer Flies bothered me for several seasons, ,unfortunatly they can mutate and cause real problems and expense.The cheapest thing to do is throw away all the baking soda salt and vinegar to the side and buy a can of flying insect kill spray your drain after evening use and see how fast the problem goes away.

  14. Thank you for all the suggestions. I am testing imidacloprid, which is sold under various names, to see if it will get rid of these pests. I will let you know if it works. Good luck to all of us!

  15. I’m also using Gentrol (hydropene). We’ve never had these before, and I hope to get rid of them for a very long time.

  16. So, I repeated the baking soda and vinegar treatment. And this time I also removed the air vent chrome thing at the back of the sink top, and cleaned it with baking soda and vinegar. I sprinkled baking soda where it comes up from under the sink, (the opening where I removed the chrome top) and poured a small amount of vinegar on top. (this could be a really bad idea generally, I don’t know). Three days now, and no more flies. Maybe I won’t need to use anything else.

  17. I have drain flies in the toilet, shower, and even in my dog’s water dish that is inside. Does this mean that they are in the water system that we drink and bath in, and if so is it safe to continue using it until we get rid of them?

  18. Third month combat those small tiny flies Rai, dishsoap and vingar trap- flying up from sink. Now they are in livingroom hallway wall. Landlird professional riach spray never elimated this getting worse.
    What should I do?

  19. I have been successful in getting drain flies under control by pouring bleach down each drain followed by boiling water.

  20. I have tried Clorox / Purex but have been concern especially with ammonia mixing flush many times the baking soda vinegar mixtures soap powders and liquids boiling hot water seen spiders and abundants of all kinds bugs. Scrub routinely ,covered drains or uncover drains makes sometimes little difference with odor. ALWAYS cleaning w solutions after fecal or urine usage in toilet. Live in apartment there is a routine spraying program which has seem to make it worse @ times more flying type insects and coming from Vents with all kinds things coming out of them plus washing room drain has had sewer gas odor that is next to ice cube connector for refrig . I empty ice cubes at least every 7/10 days noted cube size vary etc and sometimes smell. Patio loaded with all kinds bugs underneath in seams of siding Black smears and bugs all over swept routinely but to no avai
    Dusting is a joke use of product with lemon scent stopped Murphy cleaning solution on wood surface????? What a joke noted it turned Milky white in bottle. Window cleaniner attracted flies Open windows is not a option. Three
    Plus vacum purchased & only pieces of one left. There. Are many dogs / cats in this facility . I do not own one but have found multiple animal like tracts black spots on floors
    Bird ???? Drippings on stairways sticky hand rails and my only trip of elevator had a strong strong odor of urine
    Appliances are not heat compliant plus whitish residue found on food when attempting cook in oven . Brownish ???? Liquid noted on around drip pan ????? Cracks around sinks oily spots black specks cleaned and return within 24 hrs. (Wanting to cook meal for family not done due to occurrences). Attempts to cook for self food comes out burn black despite of lower temp adjustments made. Cookware destroyed Latest second ??? Insect or/ an chemical interaction with bod
    Multiple soaps changes for body use, new towels wash cloths cleaning cloth toilet papers have noted flies cling to haning tool of tissues various brands purchase checking to see if precautions for SEPTIC tanks etc. have see insect ?oii??water spots on wall /baseboards on my and adjacent apartments ????? Oil orangy spots on carpet in room not occupied . Paper shredder destroyed had been used prior
    In this apartment to shred pers.letters that had picked thru some removed so I shredded the remainder that I found At this time All recent prof . Evaluations missing Connecticut nursing license , audiology certi & numerical evaluation in key areas etc . For RN license etcetc

  21. Before all the chemicals, try to pour couple cups of vinegar down all the drains. Also use a spray bottle fill with IPA and spray down the moth flies you see on your bathroom walls (kills on contact).

  22. Main drain in our street became blocked and sewage was filling up under the floorboard of 4 houses. contacted Scottish water who sent someone out to drain from under our houses. Now infested with drain flies. AAAARRRGH there are thousands of the little buggers. Had a guy out yesterday and sprayed something under the floorboards. It is all contained to the ground floor of the house. I want to move out but hubby says we stay they go.

  23. I have 5 to 10 flies an hour coming into my bathroom and they settle on the window. I kill them and more show up again. I have tried to see where they come in but so far I have not been able to determine that. At first I thought they were coming in at cracks at the window but I am not sure now. If I have drain flies here are a few questions.
    1. How do the drain flies come through the liquid in the p trap?
    2. Can you test to see if you have drain flies by capping all the drains in the bathroom and seeing if they still show up?
    3. How can you determine if the flies are drain or gnats or regular flies since I cannot examine the flies closeup since they have already been killed.

    • Drain flies are easy to see. The dead flies look just like the pictures you can find on the internet. If killed they become dust-like. From what I’ve read, they lay their eggs in the gunk in the drain or on rotting wood from a leaking drain. Also, I have researched products high and low trying to find something to rid my house of the pesky critters. For months I have poured baking soda, salt & vinegar down the drains overnight & closed the stopper, only to wake you find flies on the bathroom walls. I tried putting tape over the sink opening. Not once have I trapped one coming up from the drain. I thought my problem might stem from the air conditioning vents sooooo, I put cheese cloth behind the vents to no avail. It wasn’t until I read a comment on this site about WD40 did I think that my problem could possible be from the flies coming up from around the seal of the toilet. I sprayed about 4 hours ago and haven’t seen a drain fly, yet. Hoping and praying this helps! If not, I’m calling a plumber.

      • Mare, what did you spray around the toilet?

  24. very helpful comments i used 2 gallons Clorax dwn sewer clean out caps put new caps sprayed all drains after 2 days ev thing gone original problem started after plumber clean backup BUT did not put caps in trap on tightly also sprayed outside breather pipe thanks for all your comments!!

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