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
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.
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
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.
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
|Drains, pipes, and slime
|Bathrooms and kitchens
|Standing water and sewage
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
- Sticky traps near drains and breeding sites
- UV light traps attract and eliminate adult flies
|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.
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.
This means it is important to maintain proper sanitation to prevent any potential health risks.
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.
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Bathroom Fly Larva
December 22, 2009
We’ve started seeing a number of these critters in our bathtub. They are 3-5 mm in length and are extremely fragile. I did this guy in trying to get him under the scope, so I don’t have a better pic. It has been a very wet fall here in northeast GA and I suspect the water is driving them to higher ground. They are driving the wife nuts and need to find out what they are and how to get rid of them.
30 miles NE of Atlanta, GA
We believe this is the larva of a Bathroom Fly or Drain Fly which is pictured on BugGuide. They are also called Moth Flies and are in the subfamily Psychodinae. The tiny mothlike adults are frequently found in bathrooms, and the larvae live in the drains.
Letter 2 – Bathroom Fly from Romania
Subject: Insect identification
Location: Iasi, Romania
April 5, 2016 1:50 am
please help me identify this insect. It’s been in my bathroom since quite a few years, and lately in my kitchen too. I live in a block of apartments. It’s about everywhere, and doesn’t fly very well or for a long time. It’s small, about 3-4 mm long/wide.
Thank you very much!
The Bathroom Fly or Drain Fly is a common household pest that breeds in the sludge that accumulates in household plumbing.
thank you very much! Now I can look forward to removing this pest.
I really appreciate your input!
All the best,
Letter 3 – Bathroom Fly from Portugal
Please indicate us another bug site
Fri, Dec 12, 2008 at 3:14 AM
Please indicate us another bug site where we can place this question. We’d like to think we didn’t lose time with this for nothing. Thank you.
Date: 12 June 2008 15:38:25 BST
We don’t know how vulgar these might be over the world but they are already very familiar to us in (the North of) Portugal. They obviously like humidity in darker places. Lately there was a problem with our WC vent and some very small dark stains (fungus colonies?) appeared on the ceiling & top of the walls. Coincidentally these sort of tiny moths appeared and started to multiply themselves (though I haven’t found any pupas or so) or coming from who-knows-where…
I fixed the problem with the vent but before I expelled the whole bunch (one by one, out the kitchen window) I made these shots of 2 or 3 individuals. Their size is approximately w5mm x h4.5mm.
They’re not buggering at all. In fact, they don’t like to be buggered themselves. Their behavior could be described as very relaxed or lazy. They can fly away like fruit-mosquitos but if they really really have to move then they rather jump away from the threat, which anyway has to be manifested very close.
I only threw them out because I don’t know what kind of bacteriological environment they might start.
Where can we see a little more info on these sort of tiny moths? We need to know if this fellow on our tap was having a funguses snack or taking some sips of our water, in which case it would be fair to share the bill with us.
Dalion & Diana
Dear Dalion and Diana,
While we understand your frustration at not having your letter answered in six months, there is no need to look any further than What’s That Bug? for your answer. Your original letter arrived while we were in Ohio visiting Mom and planting her tomato plants. Hundreds of emails arrived in our absence, and we can honestly say that hundreds went unanswered. Between May and September, What’s That Bug? gets over 100 emails per day and we are a small operation that can only answer possibly a quarter of those letters and some days we can post about 10 letters to our site.
This is a Bathroom Fly, Clogmia albipunctata. It is a Moth Fly in the family Psychodidae. The larvae live in the sludge that accumulates in drain pipes. Now that you know what they are, you should be able to find additional information online. We like that your background color of your composite matches our website.
Letter 4 – Bathroom Fly in Canada
bug found in the mens washroom at work
July 13, 2010
Hello – a very silly request so I apologize in advance – but there’s a fly in one of our washrooms here at work that i’ve never seen before. Googling does not get me the results I hope for.
Bored at work
Toronto, Canada – 6th floor
Dear Bored at work,
We wondered if perhaps the problem you had identifying this Bathroom Fly (yes that is its name) had anything to do with the semantics of the word “washroom” as opposed to bathroom, so we did a search of “fly” and “washroom”. On the first page of possibilities was a website with an image of your creature. Bathroom Flies in the subfamily Psychodinae are also known as Moth Flies, Drain Flies, Sewage Flies or Filth Flies according to BugGuide.
Letter 5 – Bathroom Fly from United Arab Emirates
Subject: Tiny weird moth
Location: Abu Dhabi United Arab Emirates
March 17, 2015 6:50 am
These little moths are all over my house and stick to the walls. They are about a half cm wide and a half cm tall. I just have no idea what they feed on or how to get rid of them. Please let me know! Thanks!
I live in Abu Dhabi… Very hot weather.
Letter 6 – Bathroom Fly
Moth like insect
September 2, 2009
I found this insect sitting on my wall. It is about 2-3 mm in length. I took my camera and clicked this snap. I am not able to identify this one. Appreciate if you can help me to find this out.
Sunnyvale, California, USA
This could well be the most detailed image of a Bathroom Fly, Clogmia albipunctata, we have ever received. According to Charles Hogue in Insects of the Los Angeles Basin: “The Bathroom Fly is often noticed indoors in damp areas – on the walls of bathrooms, showers, lavatories, and washrooms. The brown worm-like larva develops in the sludgy organic muck that accumulates outdoors in shallow pools and tree holes and, under artificial conditions, in sink traps, drains, and dead-flow areas in the household plumbing.” Your observation that this is a Moth like insect is right on since the family Psychodidae, is know as the Moth Flies.
Thanks so much Daniel. The information was helpful. I do photography as my hobby and just love macro photography. Will definitely use your website for any bug identification. Your site is of great help.
Letter 7 – Bathroom Fly from New Zealand
February 27, 2010
i could not find anything on this bug, so i hope you could tell me what it is! it is a moth that i found on one of my walls inside, it is the second one i have seen this month- have not seen before! it is small, about half a centimetre long.
New Zealand, North island.
THough it resembles a moth, this Bathroom Fly is really a fly in the subfamily Psychodinae, the Moth Flies. There are genera in the subfamily that look alike, and BugGuide pictures many species found in North America. Bathroom Flies or Filter Flies as they are also called are often found indoors in damp bathrooms because they breed in the muck that accumulates in plumbing.
Letter 8 – Bathroom Fly from Australia
What the heck might this be
Location: Queensland. Au
September 18, 2010 12:11 am
Thanks for the info on the lacewing nymph. Now to this one. It is only about 3mm body length, has antennae and legs like a moth but appears to only have two wings like a fly. Do you have any idea on what type of thing it may be?
The book is looking good, hope it sells really well.
This is a Bathroom Fly or Drain Fly, probably in the genus Clogmia in the Moth Fly family Psychodinae. According to BugGuide: “Adults often found around sewage installations, in public washrooms, and bathrooms in homes, and are attracted to light; larvae live in organic sludge that forms on inner surfaces of drains and sewage pipes; pupae occur on the surface of the organic film that the larvae have been living in.“