Home drains are prime spots for stagnant water and bacteria to accumulate, especially if the sinks or drains sit unused. If you’ve suddenly noticed an abundance of very small, mothlike insects hanging around your sinks, showers, or bathtub, you may have drain flies. These common pests can reproduce in just 48 hours, making it easy to find yourself with an infestation in days.

Unlike some other pest infestations, getting rid of flies can be quick and simple. With a little diligence, you can stop them in their tracks using basic products or pantry items and create a plan to prevent them in the future. In this guide, we’ll explain how to get rid of drain flies and mention which professional pest control companies to call.

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What Are Drain Flies?

Drain flies go by a few nicknames such as moth flies and sink flies. They’re about the same size as gnats and fruit flies—between 2 and 5 millimeters—but can be distinguished by their small, mothlike wings and round, fuzzy bodies. Drain flies also differ in color compared to other house flies, typically ranging from pale gray to black. While they look like moths, these little creatures can’t fly far. You’ll notice that they make large hops from place to place instead of buzzing around like other pests.

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Where Do Drain Flies Come From?

Drain flies live and breed around the following areas:

• Kitchen and outdoor sinks
• Shower and bathtub drains
• Basement sinks (especially those that go unused for some time)
• Sewers
• Septic tanks
• Soil that contains sewage

One common denominator among all of these places is slow-running or stagnant water. Drain flies can lay eggs in the film that forms on the inside of pipes and drains when water pools and collects sewage. For this reason, drain flies may also be attracted to:

• Wet mops and buckets
• Compost piles
• Storm drains with standing water
• Wet areas around garbage, birdbaths, or barns

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What Do Drain Flies Eat?

Drain flies primarily live on organic material found in standing water, typically when these contaminants cause a film to build up in humid, enclosed environments. Because of this, your drains are an ideal place for drain flies to thrive and reproduce. They can also find food and moisture near a collection of garbage, animal waste, or compost.

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Are Drain Flies Harmful?

In short, drain flies are not harmful to humans. Though drain flies consume and live in sewage and bacteria, they aren’t disease-carrying insects and don’t bite or sting. They could potentially spread bacteria from drains, but no disease transmission has ever definitively been linked to drain flies. Overall, they cause no proven harm to your health, though they can be a serious nuisance in your home. As noted before, drain flies reproduce quickly, spreading nests throughout your pipes that can be costly to clear out if left unchecked.

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How To Tell if You Have Drain Flies

If you’ve started to spot these tiny mothlike flies around your home, you may not immediately realize you have an infestation growing in your pipes. There are a few sure ways to check if more drain flies are living and breeding in your pipes.

Duct Tape Test

Place a piece of duct tape on top of your drain and seal it off overnight. Drain flies will eventually try to come up to the surface but will get stuck to the tape on the way out. Not only does this take care of some of the flies in your drain, but it can indicate the size of the infestation. Repeat several nights in a row to fully assess the issue.

Check for Larvae

Drain flies frequently lay eggs in the organic material that builds up right at the opening of your drain. Remove the drain cover, scrape some of the slime off the sides, and look for thin, tubelike drain fly larvae. If you don’t spot any but are certain about an infestation, the eggs may have been laid deeper within your pipes.

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Ways To Get Rid of Drain Flies

To control drain flies, the University of Kentucky Department of Entomology recommends eliminating their breeding grounds. Depending on the degree of the drain fly infestation, you can take a natural or chemical route to get rid of the pests. In many instances, it’s possible to quickly get rid of drain flies with common items found in your kitchen or under the sink.

Natural Ways to Get Rid of Drain Flies

In some cases, flushing out your drains can remove both the drain fly larvae and the conditions needed for them to return. Use these methods both as preventive and management tactics for dealing with your infestation.

• Boiling Water: The simplest method to clear out a drain fly issue is by pouring boiling water carefully down your drain 1–2 times a day for about a week. This will ensure that the flies don’t return overnight if the water fails to catch all of the organic material built up inside. Note that you should only use boiling water in metal pipes, not PVC pipes.
• Clean the Drain Manually: If you can’t use boiling water or if the infestation continues after doing so, take a pipe brush or drain snake and scrub the drain and pipe interior by hand. You can use mild soap, but scrubbing is what’s most effective. If the drain has a U-trap, remove that and clean it as well.
• Soap + Water + Sugar + Vinegar: Add a few drops of dish soap to a bowl of water, sugar, and apple cider vinegar. Leave the bowl out for a few days close to the drain to attract drain flies to the sweet solution. The thickness of the added soap will trap the flies in the water. Note that this will only kill adult flies, not larvae.
• Apple Cider Vinegar + Plastic Wrap: Create another common do-it-yourself (DIY) fly trap by covering a bowl, jar, or mug with plastic wrap. Fill the bottom of the container with an inch of apple cider vinegar. Punch small holes in the top of the plastic to allow the flies in but not let them escape. This will also only kill adult flies.
• Drain + Duct Tape: Use our detection method mentioned above to eradicate some of your drain fly issues. Seal off the drain with duct tape overnight for several nights in a row to catch the flies that try to reach the surface. This is only effective for minor infestations.

How To Get Rid of Drain Flies With Cleaners

Experts at Ohio State University mention that no insecticides are safe to pour down the drain. However, some products marketed as “drain fly killers” are instead drain cleaners that kill the bacteria and film that flies feed on. When you do use chemical cleaners, always read the instructions, and don’t mix them with other chemical or natural cleaning products.

Traditional Drain Cleaner:

After flushing your drain with warm water and giving it a pass with a metal pipe brush, you can clean out the remaining residue with products like Drano or Bio-Clean. Check if it’s safe to use these products more than once if necessary and see whether they can be used in drains outside of the bathroom.

Enzymatic Cleaners:

These products aren’t insecticides at all. Instead, they’re gels or cleansers that coat the insides of drains and pipes to kill drain fly larvae. Never pour pesticide down the drain as it could harm your pipes, septic system, and the environment.

• Green Gobbler: This popular fly killer is safe to go down drains, septic systems, and even garbage disposals.
• Natural Armour: This gel-based drain cleaner is ideal for tricky pipes that require an expansive cleaner to catch any additional nests or flies.
• American Biosystems: Typically recommended for commercial drains, this is an extreme option for clearing bacteria out of drains, specifically when dealing with a drain fly infestation.

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How To Prevent Drain Flies

Drain flies look for pools of sitting water containing sewage and other organic material. Preventing drain fly infestations requires clean pipes that are frequently flushed out with water or cleaning solutions in extreme cases. If you have a drain that frequently goes days or weeks without use, close it up with a stopper so drain flies can’t find a home there in the meantime.

Always keep an eye out for early signs of an infestation, even if you just see a few drain flies. Taking precautionary steps to check and treat a potential problem could save you time, effort, and money in the future.

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Professional Drain Fly Control

Some drain fly infestations are too stubborn or deep within pipes to go away using DIY treatment. Seasoned professionals can eliminate drain flies quickly and effectively using better tools and products than most homeowners have access to.  We’ve reviewed the nation’s top pest control providers. Here are our favorites for drain fly control based on experience, price, and customer reviews.

Terminix

The Terminix team offers extensive pest control services in all states except for Alaska, Vermont, Montana, North Dakota, and South Dakota. Terminix provides different tiers of plans depending on your needs. This pest control provider has outstanding customer service, flexible prices, and more than nine decades of experience.

Orkin

Orkin has been tackling pest control issues for homeowners across the U.S. for more than a century in all states except for Alaska. The company practices integrated pest management and has excellent reviews.

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FAQ About Drain Flies

What causes drain flies?

Stagnant pools of water, especially in pipes and other drainage areas, attract drain flies. These small, gnatlike insects feed on and breed in bacteria-ridden waste. Organic material can build up along the side of drains quickly, welcoming drain flies to eat and reproduce.

How long does it take to get rid of drain flies?

Most drain fly infestations can be managed in under a week with persistent treatment. If the issue doesn’t respond to DIY solutions, you may need to consult a pest control professional to get to the root of the larger issue.

Will Drano kill drain flies?

In most cases, Drano will kill drain flies, especially if it’s a Drano variety that expands within the pipes. For long-term treatment, however, you’ll need to take precautionary steps to keep the drain flies from returning.

Will drain flies go away on their own?

If you allow the standing water in your pipes or property to go unchecked, drain flies will rarely go away on their own. Warm homes even allow drain flies to live throughout the winter. Be sure to take preventive measures after flushing out your system to keep drain flies in check.

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Our Rating Methodology

We back up our pest control recommendations with a detailed rating methodology that we use to objectively score each provider. We review pest control plans, navigate the provider website, speak with customer service representatives by phone and online chat (if available), request quotes, and analyze customer reviews for each provider. We then score the provider against our review standards for plans and services, reputation and customer responses, customer service offerings, workmanship guarantees, financing, and availability to arrive at a final score on a 5-point rating scale.

To share feedback or ask a question about this article, send a note to our team at reviews@thisoldhousereviews.com.