Flies

How to Get Rid of Drain Flies

Drain flies control, also known as sewer flies, moth flies, or filter flies are common nuisances in homes, especially in the bathroom and the kitchen. Drain flies can be easily identified by their appearance. These tiny creatures are usually:

  • About 1/5 of an inch in size.
  • Brown or gray in color and appear fuzzy and covered with hair.
  • Fly in jerky or irregular patterns.
  • Equipped with wings that are leaf-shaped, have parallel venations, and are bigger than their body.

If you see insects like these in your home, either in your kitchen, bathroom, or in any moist area, you should get rid of them right away.

The Drain Fly

A drain fly is basically a gnat. It does not bite or sting; however, it can be really annoying as it jerkily flies around in your bathroom, kitchen, sink, and just about any area that has standing water and slime that are over there for a week.

Drain flies develop in moist areas where there is shallow standing water. Compost bins, drains, pipes, and garbage bins. Most of the time, they are found in bathrooms of homes that have been unattended. Once water starts flowing, these drain flies often disappear.

If these annoying insects persist for several days or even increase in number, most likely, there’s a nearby breeding ground where drain flies can lay their eggs and eventually multiply.

Drain flies usually lay their eggs in areas where there is moisture. They deposit their eggs in the thin lining that accumulates in the drains of your bathtub or sink. After the eggs hatch, it will only take 10 to 15 days for the larvae to mature into adult drain flies.

Drain flies become more active in the evening, congregating around sinks and shower areas, and feeding on moist organic materials often found in those areas. Their average life span is one to three weeks. They are capable of multiplying even faster by laying hundreds to even thousands of eggs.

Drain Flies: More than a Nuisance

Drain flies mysteriously appear out of nowhere instantly. One day you have a nice clear bathroom — the next day you’ll be surprised to see your walls littered with these little buggers. Even though these insects do not bite or sting, they still bring some danger to humans, aside from being really annoying.

Since drain flies dwell in filth, they may carry bacteria and other disease-causing organisms and transmit them to humans, making them a significant health concern. In large numbers, drain flies may also affect people with weak respiratory systems, particularly those with bronchial asthma. (Learn how to get rid of asthma)

Sources of Drain Flies

Drain flies can live and thrive almost anywhere as long as there is enough moisture. Any place where water has remained stagnant for over a week is an ideal hotspot for these gnats.

In homes, drain flies are often found in areas where there is an abundant supply of fine slime such as in drains, bathtubs, infrequently used toilets, damp basements and garages, water tanks, in between bathroom tiles and walls, or in roof gutters.

It is possible for drain flies to breed outdoors and enter homes through doors, windows, and other openings in search of food and a place to stay.

Getting Rid of Drain Flies

You have to go straight to the source first. Eliminating the adults that hang around in the walls and ceilings of your bathroom and kitchen will do no good because they will soon be replaced by the eggs that already have been laid.

It is very important that this problem be dealt with as soon as possible. Here are the things you should do:

  1. Identify breeding grounds both inside and outside of your home. It may difficult to see drain fly eggs and larvae due to their small size, so the best thing you should do is to clean all the areas in your home where slime and stagnant water is found. If you have an air conditioner, check the area where it drains. That is another common, yet overlooked place where drain flies may breed and thrive. (Tips on how to clean an air conditioner)
  2. If you have identified your drains as potential breeding grounds of drain flies, then you should clean it up using drain gel. Pour the drain gel at night. For the drain gel to be more effective, clean the drain pipe with a traditional metal pipe brush and remove any accumulated hair and grime.
  3. You can also use a caustic drain cleaner to easily break down the slime build-up. Use this type of product only when the slime in your drain is too thick to handle using drain gels and metal brushes. Remember that caustic drain cleaners may damage some pipes. Make sure your drain pipe can handle it. Be very careful when handling this type of chemical as it may burn your skin.

Getting rid of drain flies is easy. Just make sure you regularly clean the hot spots mentioned above to prevent them from coming back. During the wet season, pay more attention to the spots outside your home since they are more likely to be breeding grounds of these pests. For more information regarding this article, read how to get rid of gnats.

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About the author

Nicole Harding

15 Comments

  • I believe I have drain flies in my indoor hot tub. It is very infrequently used. I read the article re: using drain cleaner; but do you have any suggestions for how to get it into the side drains of the tub? I’ve filled the tub with water, vinegar, and salt and started the jets on two occasions, but still have the flies. This appears to be the only infected area in the house. I also placed tape just over the drain itself while we were away for a week, and saw no evidence of flies which leads me to believe, they’re in the jets. Thank you for any suggestions you may offer.

  • You mention putting a drain gel into your drains to kill drain flies.
    You do not tell us what gel and where to buy it.
    Please reply

  • i had the same prob and still cant get rid of them but with my indoor hot tub they came in from the drain because there was a small crack in it and that where they laid there eggs, you may have to un caulk 1 side to see if the infestation is in there

  • Sondra say:

    I’m dealing with the same problem. located the leak under the house,
    repaired the leak and still haven’t found where they’re breeding. Purchased gel drain cleaner on line and used the product for several days and the flies have increased. I was wondering do I need a plumber or exterminator HELP!!!

  • I have a “Green Cleaning chemical called EcoCatalyst”. I gave a 1 quart sample to the maintenance manager for the city of Shelton CT. He had a drain fly infestation in his mens & womens dressing rooms for the community pool. I told him to use 1-2 ounces in the wash bucket, clean the floors and walls and urinals and poor the remainder into the drains. I can sed you the results from his oun words. It not only cleaned and got rid of any odors, the flies are gone. No food source, no flies.
    I can send you information if you give me an email address.

    Terry Rich President, A-Ray Systems

  • Use just regular bleach and pour it down all your sinks! It works and it is way cheaper than any kind of drain gel..

  • I don’t have a TIP; I have a serious question. Does anyone know how to get rid of drain fly eggs and larve that got into a human thru an open cut in a hand while replacing a bathroom toilet with a filthy wax ring. A large number of adult and smaller drain flies came out of the open tile when the toilet was removed. The eggs and larve have litterly exploded in my body and Drs. won;t believe me when I tell them what happened. Someone please help if you can.

  • I believe we have drain flies. I found a leaking drain pipe under my kitchen crawl space. I fixed the pipe and drained the accumulated water and now 2 months later these flies have appeared. I have tried bleach water in a spray bottle on the crawl space floor and bug sprays. I plan on cleaning the drains with a bio type product but what can I do to treat the problem if they are in that soil under the crawl space?

  • TO: Norm Halverson
    Norm I believe in the uses of Colloidal Silver. Many online places you can read up on it. Colloidal Silver is an old remedy for body pests. Also grapefruit extract, ect…
    I once had to threaten my Kaiser Dr. that I would go to the farm store and buy livestock liquid for worms. Knew I had some pinworms but he didn’t believe me. Finally gave me 2 little pills that did the trick. We lived in the country and my kids got them several times. Easy to get from animals and the dirt.
    Good Luck, Hope you can find something that works for you, Katie

  • Do NOT use vinegar for cleaning when there are drain flies.. they LOVE vinegar!! that is one of the things used to trap them, they are attracted to it!!! they like cider vinegar the best.

  • Thanks for all the tips! I’ve been dealing with this issue all summer long and now I’m going after these suckers! Thanks to all who commented.

  • How can i get gnats out my house they are flying everywhere and i have no fruit or veggies out in open but my shower leaks in basemnt

  • Last year I read somewhere a formula that was apple cider vinegar and dish liquid and the flies were drawn to it and then fell in and drown. Does anyone know the ratio of vinegar to dish liquid and if there was a third ingredient?

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