Drain Flies 101: Must Know Facts for Getting Rid of Them

If you want to get rid of drain flies for good, you’ll need to consider all potential hiding spots in and around your drains. These common pests live in drains and lay eggs in tiny cracks and crevices within grout, shower pans, garbage cans, storm drains, or bathrooms. Since they can carry pathogens on their feet, they are considered a health hazard.

We are here to help you develop an actionable attack plan!

The Best Way to Understanding Drain Flies

Drain flies, often known as moth flies, are tiny insects you might spot around your drains or hanging out on your walls. They are typically 1/5 to 1/6 inch long and have a unique furry appearance, which is why they’re compared to moths. Identifying them is easy due to their gray or tan bodies and fuzzy ” moth-like” wings.

Adult drain flies are around 1.5 – 5 mm in size.
The hairs on their body are hydrophobic, meaning they won’t drown when submerged in water. The hydrophobic hairs are why you can’t wash them down the drain. Resource: Speirs, N.B., Mahadik, G.A. & Thoroddsen, S.T. How drain flies manage to almost never get washed away. Sci Rep 10, 17829 (2020)
They can fly and jump. If you’ve ever sprayed one with your shower hose, you’ll see how quickly it jumps away.
The larvae are 4 – 10 mm long and need stagnant water to survive.

Here’s a quick rundown of the life cycle stages of a drain fly:

Stage	Description
Egg	Laid in organic-rich moist environments. Hatch in a few days.
Larva	Live in the biofilm of drains or cracks in grout, or anywhere that’s wet. Can last a few weeks.
Pupa	Transitional stage before becoming an adult. Can last a few days.
Adult	Lives about two weeks; prefers darkness.

You’ll find drain flies in areas where stagnant water accumulates, such as near sinks, showers, and floor drains. They are attracted to the slimy film that accumulates in pipes. The thing is, you may not even know there is stagnant water if there is a tiny crack in your grout where it’s accumulating.

Drain Fly Habitat and Breeding

Drain flies thrive in moist habitats, like a shower drain.
Their breeding ground is decomposing organic material found in drains.
The larvae will hide out in the cracks and gaps in your shower.
You’ll need to consider your entire shower when thinking about how to get rid of them. If your caulk or grout is getting cracks, then that is enough space for a drain fly to lay eggs.
Don’t just focus on your drains; consider every crack and crevice in your shower, kitchen, and bathroom.

Drain Fly Prevention Tips – Think Outside the Box

We helped a client solve a complicated drain fly issue. Everything online always talks about clogged drains and biofilm, but this was a brand-new drain and a renovated bathroom.

These people tried everything, including boiling water 2x a day, steaming the shower daily, and pouring bleach twice daily. But the drain flies persisted.

It’s all because the larvae were living in cracks in the grout. Once these people re-grouted their entire bathroom and sealed up the larval hiding spots, the drain flies eventually disappeared.

So if you have tiny flies in your bathroom, it’s time to take action.

seal up bathroom shower (before and after) for drain flies

Regular cleaning of drains can prevent infestations.
Ensure your plumbing is in good condition to avoid creating breeding grounds.
You must consider the lifecycle and where the larvae and pupa hang out.
Seal up all cracks in grout and tiles.
Seal up the walls and floors of your shower pan.
Don’t leave any gaps in the walls or floors.
Use a DUPRAY NEAT Steamer daily to shoot hot steam down your drains.
Use the DUPRAY NEAT Steamer on all tiles in your bathroom. The steam will help kill off any larvae or eggs.

Remember that while they’re a nuisance, drain flies are not known to transmit diseases to humans directly. However, they are a health hazard since their feet can transmit bacteria. Their presence can indicate a plumbing problem or cracks in a tile that may need your attention.

Identifying Drain Flies

Recognizing drain flies is essential in addressing any infestation. Their unique physical traits and preferred habitats make them distinguishable from other household pests, such as fruit flies.

Physical Characteristics

Drain flies, often known as moth flies, are tiny insects typically measuring about 1/8 inch in length. They can be identified by their unique fuzzy bodies and wings, which are covered in fine hairs. When observing them, you’ll notice their leaf-shaped wings, which differentiate them from other flies.

Body Color: Usually a dull, non-metallic gray or tan
Thorax: Attached is a single pair of wings up to 2.9 mm
Wings: They are covered in dense hairs called macrotricha
Weak Fliers: A drain fly cannot fly far; instead, they are excellent jumpers.
Hair: The hair on the wings, legs, and body helps to keep drain flies dry.
Eye Color: Typically black or red
Wing Pattern: No distinct patterns, but numerous hairs give them a moth-like appearance
Legs: Covered in leaf-like hairs

Typical Habitats: Top Breeding Site

Your home’s moist and organic-rich environments create ideal breeding sites for drain flies. They are called drain flies because they are commonly found in and around drains where they can find ample organic material. Any area experiencing damp conditions can become a place for drain flies to lay eggs.

Sinks: Kitchen and bathroom sink drains
Showers: Especially those showers that have gaps in the grout and calk
Sewage Systems: Areas with standing water and sewage residues

By understanding these characteristics, you can better identify and manage drain fly presence in your home.

Life Cycle of Drain Flies

The life cycle of a drain fly encompasses four distinct stages: eggs, larvae, pupae, and adults. Each stage is critical for their development and survival.

Eggs

Drain flies begin their life cycle when a female lays eggs in a moist, nutrient-rich environment. You’ll usually find these eggs in the slimy film inside drains. When the eggs hatch, the bathroom scum becomes a food source.

Quantity: Female drain flies can lay up to 100 eggs at once.
Hatching time: The eggs hatch within 48 hours.

Larvae

After hatching, the legless larvae feed on the organic material found in their environment.

Duration: This stage can last an estimated 9 to 15 days.
Appearance: Drain fly larvae are dark or transparent and resemble tiny worms.

Pupae

Following the larval stage, the next phase is the pupal stage.

Location: Larvae encase themselves in a cocoon on the surface of the breeding material.
Transformation: The pupal stage lasts around 20 to 40 hours, during which the larvae develop into adults.

Adults Drain Fly

Finally, the adult drain flies (with their hairy bodies) emerge from their cocoons, ready to mate and repeat the cycle.

Lifespan: Adults live for about 20 days.
Appearance: These tiny flies have a distinctive moth-like appearance with wings covered in a fuzzy coating.

Preventing Drain Fly Infestations

Keeping drain flies out of your home involves routine maintenance and proper organic waste management. Since they lay so many eggs at once, you can see them turn up in large numbers as the hundreds of eggs hatch.

How do you get rid of drain flies if nothing else works?

The best tips for getting rid of drain flies:

First, rule out clogged pipes or drains by snake-cleaning your drains and using an enzyme drain cleaner for a few weeks.
Every time you see a drain fly on the wall, smash it because you are preventing that one from laying hundreds of eggs.
Pour an entire tea kettle or pot of boiling water down the drains twice daily for two weeks.
Use a Dupray NEAT steamer on all surfaces and drains in the room where you see the flies.

MOST IMPORTANT: use waterproof caulk, sealant, or grout on all cracks and crevices. This will remove the spaces where the larvae are hanging out.

Repeat all of the steps above until the issue is solved!

Regular Maintenance for Drain Fly Access Points

Weekly Cleaning: To prevent drain flies, clean your drains at least once weekly using boiling water, non-corrosive gel-based, or enzyme drain cleaner. Avoid using bleach, as it only provides a temporary solution. Did you know the larvae will immediately start climbing and crawling away from where you place the bleach?

Boiling Water: Pour boiling water down the drains to help remove the organic matter where drain flies may breed.
Drain Brush: Use a drain brush or a plumber’s snake to remove the gunk that has built up physically inside the pipes.

Seal up Shower Floor: Use a watertight sealant for showers to seal up any cracks on the shower floor.
Grout Sealant: Make sure your grout is not separating. If there are slim spaces, then that can build up with organic debris, which is a perfect food source.

Organic Waste Management

Compost Bins: Ensure your compost bins are well-managed.

Covered Bins: Keep bins covered to reduce attracting flies.
Regular Emptying: Empty and clean the bins frequently to minimize the accumulation of organic waste.

Garbage Disposal Maintenance:

Routine Flushing: Run your garbage disposal regularly with plenty of water to clear waste.
Cleaning Agents: Periodically, grind ice cubes and lemon peels in the disposal or use a biodegradable cleaner to remove potential breeding sources.

Natural Remedies for Drain Flies: DIY Solutions

The good news is that natural DIY solutions can effectively reduce drain fly populations. Use these simple remedies with items you may already have at home.

Homemade Traps

Apple Cider Vinegar Trap: (these work better for fruit flies)

Fill a glass cup with apple cider vinegar, water, and soap. (I like to use a mini glass mason jar because then I can visually see how many flies are trapped)
Cover it tightly with plastic wrap and poke small holes.
Place near the drain; flies get trapped after entering.

Sugar and Baking Soda Trap: (these work better for fruit flies)

Combine 1/4 cup sugar, 1 cup water, and one tablespoon baking soda in a bottle.
Wrap the top with plastic and make holes.
The sweetness attracts flies, and baking soda disrupts their digestion.

Put a Sticky Trap Over the Drain:

Take a standard sticky trap and form it into a tent.
Place this over the drains in the bathroom where you see the most drain flies.
The moth flies will get caught in the sticky trap, letting you know which drain in your house to focus on.

Essential Oils

Eucalyptus Oil Spray:

Mix ten drops of eucalyptus oil with 2 cups of water.
Spray around affected drains regularly to deter flies.

Lavender Oil Soak:

Soak a cloth or sponge in lavender oil.
Place it near the drain to repel flies with its scent.

Chemical Treatments for Drain Flies

When tackling drain fly infestations, you have chemical options such as insecticides and growth regulators. They effectively target different stages of the drain fly’s life cycle. We don’t recommend pouring chemicals down your drain, as this can harm the environment.

Insecticides

When choosing an insecticide, make sure it’s specifically labeled for use against drain flies. Common active ingredients you’ll find include:

Pyrethrins: These are contact insecticides that quickly knock down adult flies.
Imidacloprid: Often found in gel formulations, this ingredient disrupts the nervous system of insects.

Application Tips: Always wear protective gloves and follow the manufacturer’s instructions.

Call a licensed exterminator to help you with the application.

Growth Regulators

Insect Growth Regulators (IGRs) interrupt the drain fly’s development, preventing larvae from maturing into breeding adults. Examples include:

Methoprene: This compound mimics juvenile hormones, hindering progression to the adult stage.
Diflubenzuron: It inhibits the formation of the insect’s exoskeleton.

Using IGRs:

Safety: Handle with care, using gloves and eye protection.
Procedure: Dilute according to instructions and apply to the drain area where larvae are present.

Professional Pest Control for Drain Flies

Tackling a drain fly infestation can be tricky, and sometimes, you may need to enlist the help of a professional pest control service to ensure effective and thorough removal.

When to Call a Professional

Persistent Infestation: If you’ve tried home remedies without success and the drain flies keep returning, it might be time to call the experts.
Large Infestation: When facing a large-scale infestation that is beyond the scope of DIY methods, you should consider professional help.

What to Expect from Services

Inspection: A professional will begin with a thorough inspection to identify the source of the infestation.

Location Identification: They will check all drains, where the walls meet the floors, grout, pipes, and potential breeding grounds.

Treatment Plan: A detailed plan is tailored to your situation after the inspection.

Chemical Treatments: Professionals may use more potent insecticides that are unavailable over the counter.
Physical Removal: Techniques such as drain cleaning can be part of the service to remove organic material where flies breed.

Preventative Measures:

Advice: Expect to receive guidance on how to prevent future infestations.
Follow-Up: Most services include a follow-up visit to ensure the infestation is resolved.

Frequently Asked Questions about Drain Flies

What are Drain Flies?

Drain flies, filth flies, sink moths, or sewer gnats are small, grayish insects with a fuzzy appearance due to their long body hairs. They typically breed and live in moist environments around drains, sewers, and septic tanks. You will need to think about the entire life cycle when trying to get rid of them.

How can you identify a Drain Fly infestation?

Look for clusters of small flies near drains.
Drain flies sit on walls near the source and are active at night.
Look for tiny worm-like creatures in your shower. These larvae are 3/8th of an inch.
Notice an increase in fly activity at night.

What do Drain Flies eat?

Drain flies feed on organic material and sludge in the drains. They thrive on bacteria and decaying matter commonly found in stagnant water.

How do you get rid of Drain Flies?

Clean drains regularly to remove organic sludge.
Use biological drain cleaners to break down organic matter.
Install drain covers to prevent flies from entering.
Use sticky traps to catch adult flies.
Pour boiling water down the drains daily.
Use a steamer to heat treat your entire bathtub or shower.

What are some common names of drain flies?

Moth flies (the most common name) due to their fuzzy, moth-like appearance.
Sewer flies, referencing their habit of breeding in sewage or dirty drains.
Filter flies are named for their tendency to inhabit the filters of sewage treatment plants.
Sink flies since you find them around kitchen and bathroom sinks.

Are Drain Flies harmful?

Although drain flies are not typically disease carriers, like mosquitoes they are signs of unsanitary conditions and can become a nuisance. Just be aware that their feet can transmit bacteria from one surface to another. Their presence, especially if they live between the shower wall and tile, may indicate a need for bathroom remodeling.

Can Drain Flies bite or sting?

No, drain flies do not bite or sting humans.

Is professional pest control needed?

Try home remedies first. If the infestation persists, consider consulting a professional pest control service for a thorough treatment. Better yet, an inspector who can look for tiny crevices where these bugs may be hiding.