Navigating the Life Cycle of Drain Flies: Strategies for Prevention and Management

folder_openDiptera, Insecta
comment16 Comments

Drain flies, also known as moth flies or Psychoda spp., are tiny pests commonly found in and around drains, sewers, and other damp environments. Their life cycle goes through four stages: egg, larva, pupa, and adult, typically completing in 21 to 27 days, although higher temperatures can accelerate this process [^1^].

These insects are particularly notable for their ability to thrive in polluted, shallow water or highly moist organic solids where they feed on decaying organic material. In homes, adult drain flies can often be seen on walls or near drains, indicating an issue with excess moisture or buildup in plumbing systems [^2^]. Understanding their life cycle can help in controlling and preventing infestations effectively.

Life Cycle of Drain Flies

Egg Stage

Drain flies lay their eggs in clusters on moist surfaces, usually near drains and other damp areas. A female drain fly can lay around 30-100 eggs at a time. These eggs hatch within 32 to 48 hours, releasing the larvae.

Larval Stage

The larvae are worm-like, living in the gelatinous film found in drains, feeding on organic matter such as algae, bacteria, and fungi. They undergo a series of molts, typically taking 10 to 15 days to complete this stage. Larval stages are important for breaking down organic waste in drains.

Characteristics of Larvae:

  • Worm-like appearance
  • Live in gelatinous films in drains
  • Feed on organic matter

Pupal Stage

Once the larvae mature, they form pupae, a non-feeding stage in which they undergo metamorphosis. Pupation occurs near the larval feeding site, and this stage may take 3 to 4 days to complete.

Adult Stage

Once the pupal stage is completed, adult drain flies emerge. These adults are small, fuzzy, and gray to black in color. They do not bite and may live for around 2 to 27 days depending on environmental conditions. Adult drain flies are primarily a nuisance due to their presence in homes and buildings.

Characteristics of Adult Drain Flies:

  • Small (1/16 to 1/4 inch long)
  • Fuzzy, moth-like appearance
  • Non-biting insects
  • Attracted to moist areas near drains

In conclusion, the life cycle of a drain fly comprises of four stages: Egg, Larval, Pupal, and Adult. The entire process, from egg to adult, can take anywhere from 21 to 27 days. Drain flies are not harmful but can be a nuisance in homes and buildings.

Habitat and Breeding Conditions

Drains and Pipes

Drain flies, also known as moth flies or Psychodidae, primarily breed in the muck, slime, or gelatinous film often found in drains and pipes. This environment provides:

  • Ample moisture
  • Organic matter for feeding

Examples of common breeding sites in drains and pipes include:

  • Kitchen sinks, where food debris accumulates
  • Bathroom sinks, with accumulated hair, soap scum, and toothpaste

Bathrooms and Kitchens

Bathrooms and kitchens provide ideal habitats for drain flies due to the presence of:

  • Standing water in sinks and floor drains
  • High moisture levels

Preventing infestations in these areas involves:

  • Regularly cleaning and maintaining drains
  • Ensuring proper ventilation to reduce moisture

Standing Water and Sewage

Drain flies also breed in polluted standing water and moist organic solids like sewage. Breeding sites can include:

  • Sewage filtration tanks and septic tanks
  • Dirty garbage containers
  • Rain barrels
  • Tree holes with collected water
  • Moist compost piles
Habitat Drain Flies Fruit Flies
Drains, pipes, and slime Yes No
Bathrooms and kitchens Yes Yes
Standing water and sewage Yes No

Compared to fruit flies, moth flies tend to focus on damp, organic matter rather than ripened fruits, emphasizing the importance of maintaining clean and dry environments.


Control and Prevention Methods

Cleaning and Home Maintenance

To prevent drain flies, it’s essential to keep drains clean and moist areas dry:

  • Remove gelatinous film in drains by using a metal pipe brush
  • Regularly pour boiling water down drains to dissolve organic material
  • Clean kitchens and bathrooms thoroughly to eliminate breeding grounds
  • Repair leaks and ensure proper ventilation to reduce wet areas

For example, clean your shower drain weekly with a pipe brush and boiling water.

Biological and Chemical Control

Biological and chemical control methods target drain fly larvae and microorganisms in the drains:

  • Introduce beneficial microorganisms to break down decaying organic matter
  • Use chemical agents specifically designed for drain fly control


  • Effectively eliminate larvae and breeding sites
  • Reduce the need for frequent cleaning


  • Require proper identification of infested areas
  • Some chemicals may harm beneficial microorganisms

Traps and Lights

Traps and lights attract adult drain flies, sewer flies, and sewer gnats:

  • Sticky traps near drains and breeding sites
  • UV light traps attract and eliminate adult flies

Comparison Table

Method Pros Cons
Sticky Traps Effective at trapping adult flies Require regular replacement
UV Light Traps Attract a broad range of flying insects May not target larvae in drains

Use sticky traps in bathrooms and kitchens, and place UV light traps in basements or other infested areas.

Impact on Human Health and Environment

Allergies and Asthma

Drain flies, specifically adult drain flies, can contribute to allergies and asthma in sensitive individuals. Their presence can become a nuisance and may trigger allergic reactions in some people. For example:

  • Exposure to drain fly hairs or body parts.
  • Inhaling dust or debris from their breeding sites.

To reduce the risk of allergies and asthma, it is essential to maintain clean drains and control the drain fly population.

Disease Transmission

It is important to note that drain flies are not known to transmit diseases to humans. However, they can potentially carry bacteria from their breeding sites, typically moist and decaying organic matter, to other surfaces in homes or buildings. Some examples of surfaces they can come into contact with include:

  • Counter tops.
  • Sinks.

This means it is important to maintain proper sanitation to prevent any potential health risks.

Ecological Role

In the environment, drain flies play a vital role in breaking down organic matter. They are mostly harmless insects and are part of the insect order Diptera, family Psychodidae, subfamily Psychodinae. Their geographical distribution spans across North America, Europe, South America, and countries like Spain and Brazil. The larvae of these flies feed on decaying organic material, converting waste into simpler compounds that other organisms can utilize.

While they do play an essential ecological role, drain flies can be a temporary problem in homes or buildings during specific periods, such as winter or when windows are closed.

To mitigate drain fly infestation, consider the following control methods:

  • Regularly clean drains using a brush or enzyme-based cleaner, avoiding harsh chemicals like bleach.
  • Repair any leaks or drainage issues.
  • Seal cracks or gaps in walls and windows.

In conclusion, drain flies are a natural part of the environment, and while they can contribute to allergies or asthma in certain individuals, they do not pose a significant threat to human health. Proper sanitation and timely control measures can effectively manage drain fly populations and maintain a healthy living environment.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

    View all posts
Tags: Drain Fly

Related Posts

16 Comments. Leave new

  • I actually think it is some sort of moth…

  • they do look just like tiny, round-winged moths.

  • Thanks guys, a fly with an identity crisis :-), very cool.

  • This is Clogmia albipunctata (see It has been in N.Z. for some years, but there is no published record…

  • How can we rid these little annoying alive things?

    • We do not offer extermination advice. Bathroom Flies breed in the sludge that accumulates in the drains.

  • Noel Arbogast
    July 25, 2016 12:56 am

    does this bug bite or burrow?

  • Hi bug man , my name is Mary I read a LOT of your stuff and I hope you can help me I don’t know what I came in contact with the only thing I seen was drain larva and I’m so confused about what’s going on with me and this big problem with drain fly it got so bad me and my husband after 35 years are getting a divorce . My oldest son says it’s all in my head and my doctor says I’m hausanating I know what I see it started with my nose when I would blow it I notice it was different I’m sorry it’s gross but I’m despert I can’t even see my grand children . Course I don’t know if I’m contagious tut not like a worm you would see out side, this is scary the E room doc gave me the medication abenzol, 3 prescription @ 12 pills and I’m still infected Iits getting worse do you have any idea what it is .im so aggravate and fear it’s going to take my life.every thing changed.if it is drain fly related what can I do to get rid of it course the larva I’m seeing in the drains in the sink it raps it self around the drain looks like it has stripes on top when I blow my nose it comes out clear but I use a nasal mist and that gives it color and OH my it’s the ugliest thing I ever seen in my l life it connects point in the front and one end has like hair can you help me please I read there’s 3 stages of this pest I think I’m at the 2nd stage the larva I’m seeing in the toilet is a white cloud. I can’t wait to hear back from you thank you. Thank you

  • Crystal Waters
    July 13, 2017 1:51 pm

    I originally came to this website to identify the bathroom fly, but the info was already there. What i want to know is do they lay eggs on piping hot food because several times I’ve had to fight one away from a plate of very hot food. They woud be very close or even on the food even though it was very hot. So i was wondering what attracted them so much to extremely hot food. Do they want the food or are the trying to lay eggs.

  • Are they dangerous? I have a crawling baby ?

  • Can I even walk barefoot?? Or my kids??????? Ohmygod feels so sick and husband thinking it’s a matter of good cleaning

  • Chong Cloudy
    April 23, 2021 7:10 pm

    Bathroom fly is resistance to insecticide. It is also carrier for the disease called klebseiella. Only a combination of antibiotic klassid and xylid can cure it by taking over a period of over two to three months. As bad ad tuberculosis. It is sometimes called second TB. Pstch all holes in the bathroom and keep it clean.


Leave a Reply

Your email address will not be published. Required fields are marked *

Fill out this field
Fill out this field
Please enter a valid email address.
You need to agree with the terms to proceed