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Drain Fly

The Complete Guide To Getting Rid Of Drain Flies

It can be quite an alarming encounter to be standing in front of your sink to wash your face and get ready for the day when all of a sudden you see flying insects begin to come up from the drain to greet you.

These filthy insects are known, quite fittingly, as drain flies and while they are relatively harmless, their presence can be rather annoying, to say the least.

If left to their own devices, drain fly numbers can grow and grow leading to a bothersome infestation until you intervene. In this guide, you will learn answers to some of the most common questions about drain flies as well as gain insight and recommendations to best eliminate a drain fly infestation in your home.

What are Drain Flies?

To get rid of drain fly you have to first figure out what is a drain fly. A common household pest, drain flies are known by other names such as moth flies, sewer flies or filter flies and thrive in places around the home where there is an abundance of moisture and organic matter.

This makes sink drains, plumbing areas and sewer lines a perfect hangout spot for drain flies. In the home, the drain fly is most likely found around kitchen or bathroom sinks because of the frequent use of these areas by humans causes a quick accumulation of organic buildup.

Drain flies are about an 1/8th of an inch and are usually black, but may also be colored brown. The distinguishing feature of the drain fly is the unique pattern of veins in its wings.

Drain flies enjoy hanging around drains and plumbing because they are attracted to the drain buildup, or scum which forms over time. This decaying organic matter is a source of food for drain flies as well as a prime area where they like to breed and create drain fly worms (drain fly larva).

Contrary to popular belief, drain flies don’t come up from the drain but rather come from outside once they smell the organic matter.


What are the Habits and Behaviors of Drain Flies?drain fly on a wall

Drain Flies are most active around nightfall and are commonly associated with living in moist surroundings. Despite the fact that drain flies are flies and have wings, they aren’t the best flyers, flying mostly in erratic herky-jerky fashion.

Adult drain flies are normally noticed by homeowners when they aren’t hiding out in drains resting on walls and ceilings of areas with heavy infestations.

Drain flies diet mainly consists of damp, decaying organic matter that accumulates in drains and damp areas in which they frequent. Some of what drain flies feed on is decaying vegetation, and other microscopic plants and animals.

The life cycle of a drain flies consists of adult drain flies laying eggs in the drains or piping in which they frequent. The drain fly eggs are brownish colored but can also be cream colored. The eggs hatches quickly, usually between a day or two.

Drain fly larva will then begin to feed on drain scum until they mature into adulthood within 9 days to 2 weeks time. Drain fly larvae are exceptionally resiliant and look like worms. Those drain fly worms are able to survive in high-temperature areas and areas with low oxygen. Once they reach the last part of the drain fly life cycle (adulthood), drain flies live between 1 to 3 weeks long.

Drain flies are usually not all bad as often times, if the drain fly infestation is small in number, they can be beneficial in breaking down organic matter that is clogging drains like a natural version of Draino.


What sort of Damage are Drain Flies Capable Of?

Drain flies do not but and do not harm humans other than being a bother. They are also not known to transmit any disease to humans. However, because they are technically a filth fly because of their tendency to be around decomposing organic matter, drain flies have the potential of contaminating food if they come into contact with food that is laying around.


What are some Signs of Having a Drain Fly Infestation?

There are two simple ways that you can determine whether you have a problematic infestation of drain flies: 

1. Encountering drain flies in infested area: This is the most obvious way to identify whether you have an infestation of drain flies. Spotting a drain fly with the naked eye when you are in the restroom or around the infested drain and you notice the drain fly emerge from the drain.

As was also stated earlier, adult drain flies can be discovered resting on walls and ceilings close to the infested drain. Since drain flies aren’t great fliers, they don’t travel very far from the infested area which is the source of their feeding and breeding.

2. Discovering Drain Flies via Testing Your Drain: There are some cases where you are not able to visually see if drain flies are present or you are not sure if you have a significant infestation. In such instances, it’d be wise to test out how bad an infestation you have via a drain test.

This can be achieved by covering the suspected pipes or drain openings with a sticky adhesive tape, preferably at night before going to bed since drain flies are nocturnal.

When drain flies try to emerge from the drain, they will get stuck to the adhesive. This will give you proof of the drain fly infestation as well as help you determine how severe of a drain fly infestation it is.


How to Get Rid of Drain FliesCleaning a clogged drain

  • Step 1: Eliminate the Drain Fly Breeding Source. Get rid of the drain scum, you’ll get rid of the drain flies. The buildup of gunk in your drains are the reason the drain flies are around so cleaning and breaking down the organic matter will repel the drain flies.

    We recommend using a concentrated drain fly gel such as Forid Drain Gel Cleaner which is specifically designed to breakdown organic matter built-up in sinks, drains and garbage disposals and other areas where drain flies harbor and reproduce.

    This product should be applied every night for at least 5 nights for maximum effect.

  • Step 2: Contact kill adult drain flies with insecticide spray. After you have treated your drains, the drain flies that are still alive will escape the drains and will be flying around.

    By using a space spray as a drain fly killer, you can treat the remaining flies. We recommend an aerosol like Pyrid Pyrethrum Aerosol as a fogger and to apply to surfaces for a quick kill.

    We recommend that after spraying drain fly killer sprays, you leave the room temporarily to let the area ventilate before re-entering.

  • Step 3: Put Preventative Measures In Place. With your drain fly problem now under control, it is time to implement preventative measure to ensure drain flies don’t return.

    The way to do this is by regularly cleaning your drains with drain cleaner and not allowing gunk and scum to build up. Also keep rarely used drains covered with a plug to prevent drain flies from seeking out the drain.

Additional Tips To Keep Drain Flies From Returning

  • Make sure that there is no stagnant water in your bathroom or kitchen.

  • We recommend spraying an IGR (Insect Growth Regulator) in your drains like Gentrol IGR Insect Growth Regulator. IGR spray prevents the drain fly eggs from developing into adult drain flies, which will drastically reduce the chances of a re-infestation.

We hope you have enjoyed this informative guide to eliminating your drain fly problem. By implementing what we have outlined above, drain flies will no longer be an issue for you going forward.

If you have any further questions or would like additional advice regarding drain flies or any other type of pest control issue, we are always available to be reached via phone (1800-479-6583), email at askapro@solutionsstores.com or online live chat with a customer support member.

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Where do drain flies come from?drain fly on walldrain fly on wall

Contrary to what some may believe drain flies do not actually come from drain pipes, rather they emerge from outdoors and fly to the drain where they are lured by the smell of the organic matter they require for nourishment and for breeding. Drain flies are able to squeeze into your home by finding tiny holes as points of entry.


Drain flies normally do most of their activity in the evening by gathering around sinks and drains. Prior to conducting drain fly control, you'll need to make sure the drain fly infestation is really coming from the drain instead of another area of the home where there is moisture problems or organic matter accumulated. Drain flies are often mistaken to be fruit flies or phorid flies which also like to hang around areas such as the kitchen or bathroom where there is rot or filth. These flies are treated using different approaches, products and methods so the drain fly would need to be properly identified before proceeding.


Conducting an Inspection For Drain Flies

To inspect whether you have a drain fly issue and to see just how severe of a drain fly infestation there is, we recommend carrying out the following simple steps:

1. In the evening right before you head off to bed, make sure your bathroom is wiped dry, especially around all the drain areas such as around the sinks, bathtubs and floor drains.

2. Using a glue board or a strip of sticky adhesive, place the sticky side down onto the drain opening. Make sure not to cover the drain opening totally or else the flies will not have any way to emerge from their hiding places to go into the drain and make it more likely for them to be caught in the sticky adhesive.

3. Leave the sticky tape or glue boards in place overnight or if you can during an entire weekend to really get a good gauge of the drain fly issue.

4. Check the tape or glue board for any captured flies. Depending on if any are captured, you will know for sure that the drain is being used as a breeding area for drain flies and how bad of an infestation there may be. If you do not discover any captured drain flies, continue this inspection test for a few more nights.

Alternative Inspection Tip: If you’re not finding drain flies in or around the drains themselves, you should try to check walls in the rooms where you suspect drain fly problems. Often, several drain flies can be found in close proximity of one another.

In some instances, drain flies can be found in weird locations such as under a loose floor tile, in the tank of a toilet that is not used often, under a sink where a leaky pipe is located among other peculiar areas. If you do know for sure that you have drain flies but the drain inspection did not turn up any flies, try placing glue boards around the room you suspect is infested. Check the glue boards daily and make a note of the glue board which has the most captured flies. Start searching in that area for moisture issues that may be attracting the drain flies.

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