What are Drain Flies?

Most drain gnats are harmless to humans, though they may transmit and spread bacteria and other microorganisms from their breeding ground to areas where people are. Drain flies do not bite, but they can be a nuisance and make for an uncomfortable living situation, as they may have been recently in contact with things like animal waste. Drain flies breed in the drains, drain openings, sewers, septic tanks, septic systems, kitchen sinks, and soil that has been contaminated with sewage which is why they are often called sewer flies. They feed off the filth and scum that build up in these areas.

Do Drain Flies Bite?

No, drain flies will not bite you. Their food source is organic material found in dirty places like drains.

Get Rid of Drain Flies

Sanitation

As simple as it may sound, the best way to get rid of drain flies and prevent them is proper sanitation. Drain flies feed on filth and scum that can build up in areas such as drains, drain openings, sewers, septic tanks, and kitchen sinks. A great way to identify which drain-source the flies are coming from is to put clear tape over the drain so that they will fly into it and get stuck.

Regular household cleaning products can be used, but we recommend using products specifically designed with microbes to eat and eliminate the scum that drain flies feed on.

Using Bio Sanitation Products

These products are specifically designed with microbes to eat and eliminate the scum that drain flies feed on.

1. Invade Bio Drain

Use Invade Bio Products in the drains and drain pipes. The use of a drain cleaner treatment such as Invade Bio-Gel Treatment will remove the organic matter and improve sanitation. Since these flies love filthy debris, you must sanitize all possible breeding grounds to get rid of drain flies. This can be poured directly into the contaminated area.

2. Invade Hot Spot

a Microbial/Citrus Foam that comes in an easy-to-use 16 oz aerosol. Hot Spot drain cleaner is an aerosol can that contains the same premium microbes and ingredients as InVade Bio Foam. The 360-degree valve allows for foam dispensing in any orientation to hit hard-to-reach areas easily.

3. Invade Bio Foam

This is another type of Invade Bio product that is particularly useful in commercial establishments. It is a concentrated bio-liquid with the use of a foamer. Invade Bio Foam contains concentrated scum-eating, odor-eliminating microbes, and a foaming agent.

4. Invade Mop Clean

These come in easy-to-use packets and are designed to be poured right into your mop bucket. These are great to use even after you have eliminated the drain fly problem because they will help prevent the build-up of scum and filth that drain flies feed on.

Pesticides and IGRs

When it comes to getting rid of drain flies, sometimes cleaning by itself is not enough. Using pesticides and IGRs (insect growth regulators) can be easily used with your sanitation efforts to eliminate and prevent drain flies and any further drain fly problems.

Drain Application

Insect Growth Regulators (IGRs) can be used in drains to prevent drain flies and their developing larvae from maturing into breeding adults.

When used in conjunction with good sanitation, IGRs can be a very effective tool to help eliminate drain flies. There are liquid concentrates such as Gentrol IGR and Tekko Pro IGR. There are traditional aerosol spray IGRs like Gentrol Aerosol as well as foaming aerosols like Tekko Trio Foam. All are effective and easy to use in drains against Drain Flies.

Contact Spray

While not labeled for use in the drains, aerosol contact sprays containing pyrethrin such as Stryker 54, CB-80, and PT 565, can quickly reduce drain fly populations. It is important to remember that this is a temporary measure, and drain fly populations will quickly increase to previous levels if additional measures are not taken to find and remove their breeding site.

Identifying Drain Flies

Do I Have Drain Flies, Sink Flies, or Fruit Flies?

So, what is a drain fly? Drain flies belong to the Psychodidae family and are often referred to as sewer flies, sewer gnats, sink flies, filter flies, drain gnats, moth flies, and phorid flies. These flies are frequently found in the drain, kitchen sink, septic tank, and anywhere else they can find wet slimy substances in which to lay their eggs. There's no need to have a pest control company or pest control professional visit your home - with our identification tips below, you'll be able to tell exactly what kind of pest you are dealing with.

Drain Fly Identification

• Drain Flies have a pair of wings and antennae with six legs.

• Adult drain fly size is about 1/16th inch long.

• Body colors vary from a tan to a light gray color. Both body and wings are densely covered with long hairs that give the body a fuzzy appearance.

• The wings fold over the body and are held roof-like over the body when at rest.

• The wings of drain gnats will become fine dust when they are swatted or mashed.

• They will hop or fly short distances if they are disturbed.

• The drain fly larvae are about 3/8" long, wormlike, and without legs. The drain fly larvae are gray, with darker colors on the ends.

It is important to note that drain flies can be easily confused with other flies, such as fruit flies, phorid flies, and sphaerocerid flies, so knowing the breeding locations for each of these is important to properly identifying your fly problem.

Fruit Flies or Drain Flies?

Drain Fly Biology and Habits

Drain flies develop by complete metamorphosis. The Psychodidae life cycle ranges from 8 to 24 days.

Inspect Your Home for Drain Flies

Adult drain flies typically breed in drains, hence the common name of drain flies. These drains are an excellent place to begin the inspection. Drain flies live off debris in the form of a sticky, humid film on the drain sides and the drain trap. You can use a metal pipe brush to scrape the sides and examine the sludge for live drain fly eggs and larvae.

Don't stop looking when one breeding ground has been located. In most cases, several breeding grounds will be present.

Here are some tips for finding the source of your drain fly infestation:

Sticky Tape Test

Place some tape over the drain opening, with some holes in it for airflow. If the drain flies get stuck on the tape as they exit the drain, you know you have drain flies.

Check Slab Floors

Sometimes, these drain gnats can come from under slab floors from broken drain pipes. Drain flies love the organic debris under this slab, so it’s a perfect breeding ground. Adult drain flies then enter the living space through cracks in the slab and back through drain pipes. To determine if they are coming up through the slab, place the masking tape over the crack as described above.

If you think drain flies are breeding under a slab, a hole must be broken through the slab to see if drain pipes have broken and the flies are breeding there. After a hole is broken through the slab, dig in the soil under the slab, and inspect. The organic debris and moist soil may be several inches under the surface. The presence of drain fly eggs and larvae confirms the site as a breeding ground.

Inspect Sewer Tank

Particularly in commercial buildings, a prime breeding ground for drain gnats is in a sump pump pit and sewer tank. The sewer tank and pump pits need to be checked for activity, even if it is not close to where the moth flies have been seen flying. Also, inspect the pits of elevators in commercial buildings for excess water or moisture.

Bathroom Drains

In homes, drain flies are generally found breeding in bathroom drain pipes, particularly those in showers. Shower pans are prone to leaking, and the area under the shower pan becomes a prime drain fly breeding ground.

If you believe that the shower is a source, it may be necessary to drill a hole into the area under the shower pan or the wall behind the shower. In most cases where these flies are breeding in this area, adult drain flies will begin emerging from the hole within minutes. Light can attract drain flies and they will fly to the hole drilled through the wall in search of it.

Moisture Areas Outside

Drain flies love moist, shady areas, so it’s important to check these locations if you want to find and kill drain flies. Check under potted plants, bird feeders, and baths, in moss-clogged roof gutters, under air conditioners, in thick mulch, or on wet ground areas.

Drain flies or moth flies, can be found in moist, highly organic debris areas such as sink drains, moist mops, septic tanks, compost piles, storm drains, pipes, dung, and rotten vegetation. Re-grouting tiles to prevent water seepage into walls will stop breeding in those sites. If found in rotting vegetable matter, the source should be destroyed.

In natural settings, drain fly larvae feed on decaying plants and animals. Removing this material as much as possible will limit how long a fly lives.

Quick Sanitation Tips

Clean dirty garbage containers, wet lint under the washing machine, and even standing water in containers under houseplant pots. Outside the home, inspect air conditioners, birdbaths, shallow, stagnant pools of water, and sewage treatment facilities upwind as adult drain flies travel with the wind.

How to Prevent Drain Flies

Drain fly larvae need moisture to survive, and they may be found anywhere that standing water accumulates. A fine slime layer can develop along the water surface in infrequently used toilet bowls and tanks. Drain fly larvae can often be found in these locations, so it is important to treat these areas properly if you want to discover how to get rid of drain flies.

The drain fly larvae can also be found in the kitchen sink, or floor drains in basements and garages, even in condensation drip pans under refrigerators. Look for the small, gray larvae wiggling in the water. These areas need to be cleaned thoroughly with attention to removing the slimy surface film. Some sites may be easy to clean with traditional methods. Other places like drains can be harder to access and can be treated with a probiotic drain cleaner like Invade Bio Drain.

It is sometimes difficult to find or recognize breeding sites because the drain fly larvae are tiny and easy to overlook. However, adult drain flies can be detected using simple traps at home. A common trap to use involves filling a bowl with a cup of vinegar, such as apple cider vinegar, and covering it in plastic wrap. Simply poke a few small holes into the plastic wrap and leave it out near the drain overnight. Once you punch small holes in your drain traps, they will be able to enter the trap, but not exit, and the vinegar mixture will kill drain flies.

Another variation of this trap is to combine a cup of baking soda, a cup of salt, and a cup of vinegar in a bowl. Pour this solution down the drain opening and let it sit overnight. In the morning, pour boiling water down the treated drain to flush the drain pipes and get rid of drain flies.