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How to Get Rid of Drain Flies in 3 Easy Steps

You want to know how to get rid of drain flies. Join the club. It’s a popular question for good reason: drain flies are everywhere.

Almost everyone has had a drain fly infestation at least once in their lives. And if you’ve ever experienced the profound irritation of bugs hovering around you as you shower, you don’t care that these flies are small and mostly harmless.

You just want to get rid of them. Stat.

Here is the full guide on how to do exactly that.

What are Drain Flies?

Almost everyone in the world has asked this question at least once in their lives: “what are the little bugs coming out of the drain?” Well, they are drain flies.

Drain flies go by many names – sewer flies, sink flies, sewer gnats, and moth flies. But they are all one in the same: true flies that like to live in places that are constantly moist with plenty of decaying organic materials to feed on.

What Do Drain Flies Look Like?

Drain flies are also called moth flies. If you examine one closely, you’ll see why this moniker is so fitting – drain flies are covered in small hairs, which gives them a furry appearance, like a tiny moth.

what do drain flies look like

They always have rounded wings, which are made up of fine, hair-like scales that disintegrate into a cloud of dust when smashed. But drain flies can range in color, from a light tan to a grey-ish taupe. Some can even appear black.

As for size, drain flies are tiny, measuring only about 2 to 5 millimeters long. And when something is so small, it’s very easy to mistake it for something else, like…

Drain Flies vs Fruit Flies

When you find tiny flies buzzing around the drain, it’s easy to think that you have a fruit fly problem. After all, most of us are all too familiar with fruit flies.

But while drain flies and fruit flies are both small, annoying, and unwanted pests, they are rather different creatures.

drain flies vs fruit flies

So how do you tell them apart?

Look closely. Drain flies are fuzzy and moth-like while fruit flies do not have tiny furs on their bodies. Another dead giveaway? Fruit flies have creepy red eyes.

Check the location. Fruit flies get their name because they like to infest decaying fruit and vegetables, garbage and garbage disposals, as well as damp organic matter like the stuff found in your compost bin. Drain flies, on the other hand, prefer to breed and live around drains, sewers, storm drains, dripping pipes, and other places where there’s likely to be moisture and standing water.

Daytime vs nighttime. Fruit flies are, like us, diurnal and as such, are active during the day. Drain flies, on the other hand, tend to be nocturnal so you’ll most likely notice them hanging around sinks and drains in the evening hours.

Observe the flying. Despite their name and large wings, drain flies are pretty bad at flying. They can only fly for short periods of time so when they move, it looks more like they’re jumping than actually flying. Fruit flies, on the other hand, excel at aerodynamics so you’ll find them easily and frequently flying around the places they infest.

Drain Flies vs Gnats

Another common household pest that gets confused with the drain fly is the fungus gnat. These flying nuisances usually hitchhike into the home on houseplants.

So how do you tell drain flies vs gnats apart?

drain flies vs gnats

Look closely. One of the most characteristic features of drain flies is the fuzzy, moth-like furs that cover their bodies. Fungus gnats have no such fur. Another dead giveaway is that fungus gnats have long, spindly legs that make them look like tiny mosquitoes at first glance.

Check the location. Fungus gnats are so called because they live off the fungus that grows on and in soil, leaf mold, mulch, compost, and plant hairs. As such, they are much more likely to be found hovering around houseplants. They’re also attracted to light so they may hang out around windows.

Because fungus gnats are not strong fliers, they prefer to stick close to where they eat and live rather than explore the great indoors. It’s unlikely you’ll find them around drains.

Where Do Drain Flies Come From?

One day, you were the proud owner of a clean, sparkling, and fly-free bathroom. Then suddenly, you are inundated with little flies in your bathroom. What gives?

The sudden and mysterious manifestation of drain flies leads most people to assume that the pesky critters are coming up from the pipes and drains they like to lurk around.

But in actuality, drain flies are much more likely to come from the immediate outdoors. Places with standing water near your property – think: birdbaths, storm drains, the leaky underside of air conditioners, wet areas around the garbage and potted plants – can be breeding grounds for drain flies.

When these flies smell organic matter in your drains, they can sneak into the house through tiny holes or open windows. And because they can reproduce in as little as 48 hours, one or two drain flies can quickly lead to an infestation.

What Do Drain Flies Eat?

The diet of a drain fly is every bit as disgusting as their preferred living quarters. In fact, they’re one and the same.

Drain flies live in drains because these areas provide a delicious buffet of decaying organic matter. You know, that mucky slime that builds up in pipes and around drains.

That is a drain fly’s favorite food.

What Causes Drain Flies?

The biggest cause of drain flies is standing water. In fact, if you have drain flies in your bathroom, that’s a surefire indication that you have a drainage problem that has been causing slime buildup in the plumbing pipes.

Here are quick facts on what attracts drain flies:

  • Drain flies thrive in standing water and the moist, decaying organic matter that it creates.
  • Not only do these conditions make good drain fly habitat, they are essential for drain flies to breed in. Drain flies lay clusters of 10 to 200 eggs at a time in shallow, preferably dirty water with plenty of gunky muck for the soon-to-hatch drain fly larvae to feed on.
  • Adult drain flies also feed off the slimy film of organic matter that builds up in drains and sewers, although they can also live off flower nectar.
  • Any place that provides constant moisture and the decaying debris that it creates, including slow or clogged drainage areas, dripping pipes, moist mops, storm drains, condensation formed on air conditioners and refrigeration units, leaky roofs, and even rarely used toilets make ideal habitats for drain flies to live and mate.

The most horrifying fact is that drain fly eggs can hatch in as little as two days and the entire drain fly life cycle can be completed in as little as a week. So if you notice a couple of drain flies hanging around your bathroom, you want to act fast. Because a handful of them can turn into a drain fly infestation quickly.

How Do You Know if You Have Drain Flies

If you have little flies in the bathroom that never seem to go away, it’s likely you have drain flies. But if you want to find out for sure, there are a couple easy tests you can do.

Duct Tape for Drain Flies

Use duct tape or a strong, clear tape to seal off your entire drain, sticky side down. The tape should be left on at least overnight.

When drain flies try to fly out, they will get stuck to the tape. This will allow you to see whether you have a drain fly problem as well as get a close look to make sure they are indeed drain flies.

Check for Drain Fly Larvae

This is a grosser option, but you won’t have to wait overnight for results. As you know by now, drain flies lay their eggs in drains so that the hatched larvae will have plenty of slimy sludge to feed on.

To see whether you have a drain fly problem, you can use a knife to scrape the sides of your drain, especially any sticky, gunky, slimy film you see on the drain sides. Examine the sludge you scrape off on your knife for live drain fly larvae.

What does drain fly larvae look like? Drain fly larvae are small. But at around 4 to 10 millimeters long, they’re big enough to be seen by the human eye. They are long and slender, tube-like maggots without legs.

If you do not see any drain fly larvae wiggling about, it doesn’t necessarily mean you don’t have a drain fly problem. If you continue to see drain flies or catch them on the tape, the eggs could’ve simply been laid deeper in the pipes.

What do drain fly eggs look like? Drain fly eggs are transparent in color and are laid in clusters from 10 to 200 eggs. But it almost doesn’t matter what they look like because attempting to identify them is a fool’s errand. These eggs are incredibly small, no larger than 1 millimeter, and because they are laid on wet, gunky materials, it will be almost impossible to spot them.

How to Get Rid of Drain Flies in 3 Steps

Successfully getting rid of drain flies comes down to doing two very important things:

  • Removing slimy buildup. The slimy film that lines drains and pipes is both a food and a breeding ground for drain flies. Drain flies of all ages – eggs, larvae, and adults – feed off this buildup of organic matter. And the eggs and larvae live there.
  • Killing drain flies. Getting rid of the slimy on the drain and pipes gets rid of the drain fly’s food source and kills drain fly eggs and larvae as well. As for the annoying adult drain flies still hanging out in your bathroom? You’ll need to kill them.

Here’s the step-by-step process to get rid of drain flies for good.

#1. Let the water flow

Here’s one universal truth: if there are drain flies, there is almost always a slow or clogged drain.

Take a peek at your shower drain after you shower as well as a couple hours after you shower. Has the water fully drained? If not, that reservoir of post-shower water is the perfect drain fly habitat.

So the first step to get rid of drain flies is to unclog the drain. You can use a plunger and go to town on it yourself. Or you can pour in Green Gobbler Drain Clog Dissolver and leave it to do its job overnight.

#2. Remove any buildup

The most important thing you can do to get rid of drain flies is remove the slimy film that builds up on drains and pipes. The drain clogger you used should’ve done much of the hard work. But a good scrubbing doesn’t hurt to fully dislodge stubborn grime as well as the drain fly eggs and larvae living in the scum.

Use a long, flexible pipe brush to reach deep inside the pipes, scrub the pipes like you mean it. Yes, it’s hard, dirty work but take satisfaction in the fact that hundreds of drain fly spawn are dying with every scrub.

#3. Use a drain fly killer

With just the above steps, you’ve wiped out the next generation of drain flies. But what about the drain flies that are flitting around your bathroom right now?

Not only are they just generally annoying, they could also lay more eggs in the drains and start a new infestation. That’s the last thing you want. So you’ll need to kill off these pesky adult drain flies and prevent new drain fly spawn from developing.

To do, you’ll need to know how to kill drain flies.

How to Kill Drain Flies

You’ve done the dreaded home maintenance necessary to make your home inhospitable to drain flies. Now, it’s time for the fun part: killing the pesky critters who insist on making your bathroom their home.

So what kills drain flies? Here are the best ones.

InVade Bio Drain Gel

If you’re going to buy just one drain fly killer, this is it. Instead of using chemicals that are harmful for pipes and septic systems, this gel uses a combination of citrus oil and microbes to do the dirty deed.

And the microbes really work magic. When they come into contact with the gunky, slimy sludge that drain flies live off, they go to work and actually digest this organic debris. The special, thickened formula of the gel allows it to cling to the sides of drains so that the microbes can fully digest the drain scum.

The result? No more slimy organic residue for drain flies to lay their eggs in and for drain fly larvae to eat. Which will soon mean no more drain flies.

Green Gobbler Fruit Fly Killer

This is named a fruit fly killer but it does a remarkable job of killing drain flies as well. The active ingredient is citronella and it comes in the form of a thick, clinging gel that coats the insides of your pipes while killing drain flies and their spawn.

The best part is that the gel is made of natural ingredients and gives off a pleasant smell rather than toxic fumes. As such, it’s also safe for pipes and septic systems. You can even use it in the garbage disposal.

And Green Gobbler stands by their products so if it happens to not work for you, you can return it within 30 days for a full refund.

Green Gobbler Drain Strips

The only downside of using a gel-based drain fly killer is that once you’ve poured it in, it goes down the drain and disappears. Of course, they coat and clean while they go down but sometimes, you want something that’s going to stick around longer.

Enter Green Gobbler Drain Strips. These little green sticks are composed of slow-dissolving enzymes that you place directly into the pipes. Once in place, they go to work eating away at the gunky organic matter that drain flies like to live and breed in.

The little sticks may look puny but they are powerful enough to combat any build-up of grease, oil, fats, and organic scum. The best part, of course, is that they deodorize while they clean. So you can get rid of stinky drain odor at the same time you kill off drain flies.

Fruit Fly BarPro

All the above drain fly killers are great for getting rid of the drain fly food source as well as the drain fly spawn lurking in your drains. But about the adult drain flies that insist on buzzing around every time you visit the bathroom?

If you want to quickly and effective wipe out all drain flies immediately, Fruit Fly BarPro Strips are the way to go. Each of these small strips activate once exposed to air. They slowly diffuse for up to 120 days, killing any drain flies that are in the area. They work by releasing DDVP, which affects the nervous system of insect pests, leading to a quick death.

It’s not just drain flies and fruit flies that these strips work on, they will also kill moths, beetles, mosquitoes, silverfish, roaches, and spiders that may be lurking around.

For such a small product, these strips are incredibly effective and just one strip can cover an area of up to 200 cubic foot.

Katchy Indoor Insect Trap

If you want to catch the jumpy bathroom flies that annoy you as you shower but you don’t want to use pesticides, a great option to get rid of drain flies is the Katchy Insect Trap.

This brilliant device is entirely pesticide-free. Instead, it uses light to entice drain flies and other annoying flying insects. It works very well for drain flies in particular because drain flies are very attracted to light. And because they are nocturnal insects, placing one of these traps in the bathroom can make it the the only source of light they see.

Once the flies head toward the attractive UV light, the fan sucks it into the trap. The sticky glue board inside makes escape impossible. The result? No more drain flies jumping around in your bathroom.

Gentrol IGR Insect Growth Regulator

Last but not least, this drain fly killer is only recommended to those with a pervasive, persistent drain fly infestation. If you’ve thrown every home remedy and drain fly killer at the problem and nothing has solved it – this one will.

That’s because this isn’t a drain fly killer, per se. Nope, Gentrol IGR targets the drain fly problem where it really hurts: the spawn.

IGR stands for Insect Growth Regulator and that’s exactly what it does. IGRs prevent the larvae from growing into reproductively healthy adults that can breed. By using it, you prevent the next generation of drain flies from reaching maturity. The result? It may take a week or two, but your drain fly problem will die out.

To use it, wear gloves when handling. It’s not a pesticide product but it can still cause irritation if it gets on your skin. You have two options to using this:

  • Mix the Gentrol IGR with drain gel and slowly pour it down the drain.
  • Make your own formula by combining 1 ounce of Gentrol IGR Concentrate to 1 gallon of water. Shake well and spray inside the drain.

We recommend treating the larvae this way every other day or after you use the shower. Rinse and repeat for a couple of weeks or until you no longer have a drain fly problem.

Do Drain Flies Bite?

There’s at least one good thing about drain flies: they don’t bite.

Not only do they not bite, drain flies are not aggressive. Compared to other fly species (we’re looking at you, tsetse fly), they’re relatively harmless.

Are Drain Flies Harmful?

Drain flies don’t bite or sting. They also don’t spread diseases. But that doesn’t mean they are harmless, especially when they multiply into an infestation.

Here are a number of ways in which drain flies can be harmful:

Because drain flies grow and live in filth, they can indirectly affect your health just by living their lives. As they travel from their breeding location full of sewage, decaying organic matter, microorganisms, and fungi, they can spread bacteria anywhere they land, like sinks, toothbrushes, countertops and food.

Drain flies have been shown to trigger allergic asthma in certain people. This is not common, however, and is due to repeated exposure.

Can Drain Flies Lay Eggs in Humans?

It only takes reading or hearing about one case of a person being infested with fly larvae to make you fear that scenario forever. For the most paranoid of us, finding drain flies buzzing around the bathroom can prompt a panicked question: can drain flies lay eggs in humans?

The answer is: yes, but it’s very unlikely.

Myiasis is an infection that occurs when flies lay their eggs in human tissue. The larvae that hatch burrow deeper into the skin. To date, there have been a few cases of people who were infected with myiasis by the drain fly, like here and here.

But fortunately, these cases are few and far between. Still worried? For the vast majority of people, myiasis isn’t a likely reality because it requires a couple other predisposing factors to be present, like:

  • Open and untreated wounds
  • No running water, causing the water needed for rinsing and bathing to be stored in uncovered buckets in the bathroom
  • Unsanitary toilets or pit latrines

If you live in North America, the chances of being infested with drain fly larvae are very low. It usually occurs in the most rural areas of tropical and subtropical countries without access to toilets and running water.

How Long Do Drain Flies Live?

The one good thing about drain flies is that they don’t live long. Even with ideal temperatures and a food source, adult drain flies only last for around 20 days. Of course, there’s bad news, too: during that short time span, they mate.

Fun fact: Drain flies mate for life. Not necessarily by choice, but they really only have the time to mate once.

Drain flies do start early, though. Within hours of leaving their pupal casings as a full-fledged adult, drain flies get busy reproducing. And this is how a drain fly infestation can get very bad, despite their short life span. A single female drain fly can lay around 30 to 100 eggs before her time is up.

These eggs take only two days to hatch and then emerge as sewage-feeding larvae. Drain fly larvae can live as long as 24 days before entering the pupal stage, which can last around a day. And then boom – more drain flies buzzing around your bathroom.

Do Drain Flies Die in Winter?

Drain flies require constant moisture and a temperature of at least 70° F. So if you live in a place that gets arctic (we’re looking at you, Canada), you may be hoping that drain flies will simply die on their own in the winter.

And you know what? You’re right. Cold weather can definitely kill off drain flies. But this means that the temperature in your bathroom, even in the drains, needs to be cold enough. If you can work with that, you may be rid of your drain fly infestation by the new year. Winter is coming, drain flies.

Of course, if you’re one of the lucky people who live in places with moderate climates all year round, you’ll need to go with one of the best ways to kill drain flies instead of waiting for your moderate winter to do the job.

Luckily, getting rid of drain flies doesn’t have to take long.

How Long Does It Take to Kill Drain Flies?

The good thing about most drain fly infestations is that it doesn’t take long to get rid of drain flies. If you use the methods above and are meticulous in your efforts, your drain fly problem could be a thing of the past in as little as one week.

For the most pervasive and persistent drain fly infestations, it can take longer. But with regular effort, your bathroom and home should be drain fly free in a couple of weeks at most.

How to Prevent Drain Flies

Once you’ve gone through the hassle of getting rid of drain flies, you want to make sure they never come back again.

Here are some tips on how to prevent drain flies. Forever.

Keep your pipes clear

Drain flies absolutely love slow, clogged drains because these pools of sitting water create the perfect conditions for slimy, organic gunk to build up. So the first course of action to prevent drain flies is to make sure the water in your drains is draining properly. Use a drain cleaner that is septic safe like the Green Gobbler Drain Clog Dissolver to keep drains clear.

Remove drain fly attractants

Even when drains are clear and free-flowing, the constant moisture in the bathroom can lead to the buildup of slimy gunk that lines the drains and pipes. Drain flies love to eat and breed in this sludge so don’t give them the chance.

Regularly clean the gunk out of your drains and pipes with a sturdy drain brush.

Pay attention to neglected drains

Run water through any drains in your home that rarely get used. This should be done at least once weekly. Even better, make sure these drains are protected from gunky buildup by placing a Green Gobbler Drain Strip inside them.

If you plan to leave on vacation, close the drains with a stopper or cover them with tape. This prevents new drain flies from moving in and creating families while you’re gone.

Flush unused toilets

Same thing applies with toilets that are rarely used, make sure you flush them at least once a week to get rid of any drain fly eggs that may have been laid in the standing water.

Remove standing water

It’s not just drains that can attract drain flies. Any area with standing water and organic residue is a potential home. That includes mops left in buckets of water, potted plants with water collected at the bottom, garbage disposals, condensation pans, and even moisture that collects under loose tiles. Check and clear these spots immediately.

Be vigilant

If you start to notice a couple adult drain flies showing up in your bathroom, it could be the start of a new drain fly infestation. The adults could have already laid the eggs to create the next generation of drain flies. Take precautionary steps to prevent the problem from escalating.

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