Drain Flies: Identify Them | Find Them | Get Rid Of Them

by | Flies, Insects

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If you see dark, moth-like flies near your drains or on your bathroom walls, there’s a good chance you have drain flies.

Drain flies are small, round, hairy flies that live near standing water. In houses, they’re often found near drains in floors, tubs, showers, sinks, and garbage disposal units. Drain flies are also called moth flies or sink flies. They sleep on walls during the day and hop rather than fly around at night.  

Let’s find out how to identify drain flies, if they can harm your family, and how to get rid of them once you know you have drain flies in your home or yard.

How to identify drain flies

Photo of a drain fly with labels to identify a drain fly or moth fly
To identify a drain fly, look for a small, dark, hairy body; veined, hairy wings; and beaded antennae.

The following table gives a list of characteristics of what to look for to identify a drain fly:

Known as– Drain flies
– Moth flies
– Sink flies
ColorBrown, gray, black
Length1/5 – 1/6 inches (4 – 5 mm)
Description– Body and wings covered in hairs
– Long, beaded antennae
– Wings longer than body
– Veins on wings
Flight patterns– Weak fliers, covering only a few feet with each short flight or jump
– Can be carried longer distances by the wind
Eggs– Brown- or cream-colored eggs
– Laid in batches of 10 – 200
Attracted to /
Where to find drain flies
– Standing stagnant water
– Sewers and septic tanks
– Clogged gutters
– Drain pans under refrigerators
– Bottom of garbage cans
– Bathrooms and humid basements, near kitchen sinks and garbage disposal units, and in drains
– Under cracked tiles
– Areas where air conditioning units drain
– Sliding glass door tracks
BreedIndoors and outdoors
Eat– Microscopic organisms in polluted water, such as algae and bacteria
– Flower nectar
Most activeIn the evening

Drain flies are not harmful

Drain flies are not harmful and cannot bite people or pets. They can become a nuisance though, especially when there is a heavy infestation. Drain flies don’t transmit diseases to humans but they can trigger asthma in some people.

Why you have drain flies

You have drain flies because they are attracted to areas in your home or yard where drain flies like to live and breed. This includes standing water in toilets or tanks while you are traveling, greasy drain pipes, clogged drains or gutters, and wet compost piles.

How to get rid of drain flies

Below is a list of recommended methods and products from Amazon that you can use to get rid of drain flies in your home and yard:

Make sure you have drain flies: Stick strips of masking tape with the sticky side facing down over the openings of your drains. Leave the tape on overnight or for a few days. Check the tape to see if flies are stuck to it and how many there are – the more flies there are the greater the infestation.

Remove grease in drains: Clean all your drains, especially those in the kitchen, with an enzyme-based drain cleaner to remove grease that attracts drain flies. This one from Amazon is biodegradable and digests grease, fats, oils, sludge and more. Use a strong, long-handled brush or flexible drain brush to scrub out the pipes.

Use a drain fly killer: Once you’ve removed any fats and oils lining your pipes, use this commercial-grade drain fly killer in your drain pipes (it also kills sewer and fruit flies). The fly killer works by sticking to the walls of your drain pipes and killing adult and young drain flies in there for months to come (this is how many restaurants and public facilities kill drain flies or keep them under control).

Put screens over vent pipes: One reader got rid of her drain fly problem by putting fine mesh vent screens over the plumbing pipes on her roof.

Seal grout and fix broken tiles: Drain flies love living under broken tiles or in cracks in tile grout, where it’s warm, dark, and wet. Take a good look at the tiles in your house. Fix those that are cracked or broken, and seal any gaps you have in the tile grout. While you’re at it, seal the edges of sinks, basins and bathtubs with a good quality silicone.

Kill the drain flies you can see: Use a traditional fly swatter or flying insect spray to kill any drain flies that you see sitting on your walls during the day. Drain flies are very slow, so it is quite easy to kill them yourself. But be prepared to wipe the wall after as squashed drain flies often leave behind a powdery smudge from the scales on their wings.

Use regular drain gel: This drain gel takes some time to work depending on the level of infestation and breeding location, but many people have had success with it where other products have failed. Use the drain gel daily until all the drain flies are gone. Simply follow the instructions and leave the gel in the drains overnight. After a few days, do another masking tape test to see if there are still drain flies in your drains. If there are, immediately use the gel again every night for several days before doing another test.

Remove standing water: Walk around your house and yard and remove all standing water that you can see. Be sure to look for stagnant water in the containers under plant pots and houseplants, under the washing machine and refrigerator, near to air conditioning units, in bird baths, and around your garden hose or irrigation system.

What doesn’t work to get rid of drain flies: Using plain hot water or bleach in your drain pipes probably won’t get rid of the drain flies living in there. Please remember not to use bleach before or after any other drain cleaning products as mixing bleach with other products can create toxic fumes.

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