Will Drano Kill Drain Flies? What About the Larvae?

Oh no. Drain flies are buzzing around the garbage disposal again. It seems every time summer arrives and the weather gets warm, these little annoyances appear out of nowhere. And thus we ask, will Drano kill drain flies?

Fortunately, you can kill off these pests overnight with a little of America’s favorite household drain product – Drano. Drano kills the flies, eggs, and larvae in no time. Presto, Drano, and the flies are as good as gone. This post gives you everything you need to know about drain flies and how to permanently remove an infestation with Drano.

What Are Drain Flies?

Whatever you want to call them; filter flies, sink flies, or moth flies - drain flies are a pain to have them buzzing around. The fuzzy, dark-colored body of the drain fly is around the same size as a fruit fly, with oversized wings for its body, giving them a moth-like appearance. They have 6 legs and are between 1.5mm to 5mm in length as adults.

The flies range in color from black to light grey or tan and aren’t as good at flying as fruit flies. Despite their large wings, they prefer hopping around the drain. With short lifespans, drain flies make the most of their time around your drain, laying as many as 300 eggs in 48 hours, meaning they can infest the drain fast.

If you have an infestation you may see little black worms in your shower, and they're not worms. They're the larvae stage of the drain fly, and given enough time will grow into the adult that can fly around.

Why Do I Have Drain Flies in My House?

If you have stagnant water around the washer, garbage disposal, or dishwasher, you’re giving drain flies the perfect conditions to set up shop and multiply. These pests feed on microscopic bacteria, sewage, and algae; you’ll find them in drainage areas inside and outside the house.

Bathtub and shower drains, outdoor, kitchen, and basement sinks, septic tanks, and sewers all provide the ideal conditions for drain fly infestations. These tiny bugs in your bathroom prefer drains that don’t have a lot of activity. So, if you have a shop sink in your garage or a guest bathroom that’s rarely used, drain flies will find them sooner or later and start breeding.

They enter your home from outside when they smell the stagnant water and start laying eggs in the drain pipe. If you have drain flies, it doesn’t mean you have a dirty home; they can show up if you take a weekend down at the lake. All it takes is a few days of undisturbed breeding conditions, and you come home to an infestation.

So now the question is will Drano kill drain flies, and the answer is yes. But let's talk about how it actually does that. But be mindful about pouring it into a dishwasher drain or your disposal. Some seals could become weakened and you can end up with a garbage disposal leaking from the bottom, for example.

How Does Drano Kill Drain Flies?

Enter Drano – the mortal enemy of the drain fly. Drano is effective at killing these pests because it stops them at the source, the drain pipe. Partially-clogged or slow-draining drains collect water which breeds the bacteria attracting drain flies to the party.

The eggs hatch into larvae, feeding on the bacteria in the drain until they turn into adult flies. Drano eliminates drain clogs, removing the standing water and discouraging bacteria from growing in the drain pipes.

The active compounds in the Drano formula kill the eggs and larvae in the drain pipe, turning it into an inhospitable environment for the drain flies. Since Drano is formulated to degrade organic materials causing clogs, it also eradicates the drain fly eggs and larvae, removing the infestation almost overnight.

One of the most effective chemicals in Drano for killing drain flies is sodium hydroxide, or lye. Even short-term exposure will wipe out the adult drain flies and their larva, as well as the eggs. You may need to smush a few flies that weren't in the drain at the time, though, so be on the look out.

Which Drano Product Is the Best for Killing Drain Flies?

We recommend going with the gel formula in the Drano range. Liquid products are effective, but the gel will have better results. It coats the walls of the drain pipe, clinging to the surface for longer than liquids.

As a result, the active ingredients in the Drano gel work longer, killing the larvae and eggs while eliminating the bacteria. The adult flies won’t lay eggs in a coated pipe; they’ll just end up reaching the end of their life cycle and dying without getting the chance to propagate the infestation.

If you use the liquid Drano product, you’ll have to make several applications six to eight hours apart to keep the drain flies from re-infesting the plumbing. There’s not much price difference between the liquid and gel formulations, and it’s readily available from most retailers.

How Long Does It Take Drano to Kill Drain Flies?

With the right Drano product and strategy, you can wipe out a drain fly infestation within 48 to 72 hours. As soon as you pour the Drano gel into the plumbing, it gets to work on eliminating the eggs and flies instantly.

You’ll need to apply the gel every morning for two to three days, and you’ll notice a marked reduction in flies after the first day, killing the infestation by the fourth.

The eggs and larvae die right away. Nothing can stand up to the powerful chemicals in Drano gel. However, the adult flies will hang around for a day or so. As mentioned, they’re a short-lived fly species and don’t last long.

In some conditions, drain flies can live up to two weeks, but adding the Drano kills them faster because they have nothing to feed on, and they’ll die after coming in contact with the Drano gel on the walls of the pipes. Will Drano kill drain flies? Oh, yes... very effectively.

We recommend adding Drano gel to all the neighboring drains around the infested area. This strategy prevents the flies from finding another spot to overrun, and they have nowhere to move on to start a new infestation.

Is It Safe to Use Drano to Kill Drain Flies if I Have a Septic Tank?

All Drano products, including Drano gel, are safe for septic tanks according to the manufacturer. It’s a plumbing-friendly product, and you can’t damage your pipes or drains by using it, even with repeated applications. Drano gel is also safe on plastic and steel drains, making it the ultimate all-purpose drain fly killer.

Many plumbers will argue against using Drano with septic systems (or at all, which is a bit aggressive). They fear that the chemicals will kill beneficial bacteria inside the septic tank. Some argue that the heat from Drano's chemical reaction will harm your pipes in general, but will suggest in the same article to use boiling water instead... so take that contradiction how you will.

Drano works well in removing drain fly infestations inside and outside the home. Regardless of where the drain flies choose to set up their home, they aren’t safe from the powerful bacteria-busting effect of Drano, removing their food source from the plumbing.

Will Drano Permanently Remove Drain Flies?

If you keep up the application of Drano gel for three to four days, you’ll permanently eradicate the infestation from the drains. However, a single application of Drano gel might not be enough to resolve the problem.

A single application may slow things down for a bit, but the chances are it will return in a few days after the Drano dilutes and leaves the plumbing system. This is especially true if you use the infested drain in the interim. It’s best to leave the drain for a few days while it clears.

Also, remember that if you decide to go with the liquid Drano over the gel, you’ll need to make regular applications two to three times a day. We recommend dosing the drain flies in the morning, midday, and night for the best results with the liquid Drano product.

FAQ’s Regarding Drano for Drain Flies 

When you asked will Drano kill drain flies, undoubtedly your mind started producing some common questions surrounding the details of this topic. Let’s cover these questions now.

Why Is it So Challenging to Eliminate Drain Flies Permanently?

Trying to wash the drain flies away with water won’t work. These pests have tiny hairs all over their bodies that repel water. Drain fly eggs, and larvae create air bubbles around their bodies, preventing them from being washed away or drowning when submerged. While bleach can kill drain flies you'll encounter similar issues with more downsides.

Should I Pour Boiling Water Into My Pipes to Kill Drain Flies?

We recommend avoiding the practice of pouring boiling water down your drain to eliminate drain flies. Most types of PEX pipes and PVC plumbing will crack when exposed to hot water, especially repeated doses of it. Cracking your plumbing pipework will present more of a hassle than the flies, and it’s expensive to repair.

How Do I Stop Drain Flies From Returning?

Pour Drano gel into the previously infested drain once a week to ensure the drain flies don’t return. This preventative strategy ensures the flies don’t have access to the bacteria they need to feed the larvae and start an infestation.

Will Fruit Flies Infest My Drains?

Like drain flies, fruit flies also love setting up shop in a bacteria-laden drain. They get attracted to rotting food in the sink drain, providing them with the sustenance they need to feed their young and start an infestation.

What Is the Most Effective Product for Killing Drain Flies?

All Drano products are effective for killing off drain fly infestations. However, we recommend going with the gel product. The gel clings to the walls of the plumbing, providing long-lasting results.

Will a Drain Fly Problem Go Away By Itself?

In most instances, a drain fly infestation will resolve itself. However, it could take weeks or months for that to happen. You’re better off pouring some Drano gel into the plumbing to kill it off early. Drano is an affordable product and worth it to remove drain flies from your home.

Key Takeaways on Using Drano for Drain Flies

Let’s do a little summary recap for the main points we’ve learned above so we don’t forget:

• Drano kills the bacteria in the plumbing that the drain fly larvae feed on.
• Drano also kills the eggs and larvae on contact.
• We recommend going with the gel formula for the best results.
• Pour the Drano gel into the infested drain once a morning for three days; the infestation should be dead in four days.
• The Drano won’t kill adult flies, but you can use pesticide sprays and paper traps to catch and kill them. They won’t be able to re-infest the same drains once the Drano gel is in place.

The main thing to remember here is you’ll still need to take care of any adult drain flies in the room. Their nest, larvae, and eggs, on the other hand, will be toast from the Drano.

So, Will Drano Kill Drain Flies?

Does Drano get rid of drain flies? It does and does so effectively. Let me state again that I recommend you use the gel formula of Drano because it will cling to the sides of the pipes, not only killing eggs and larvae but also it will eat away at the gunk and bacteria that the drain flies are in there feeding off of. So, will Drano kill drain flies? It will get rid of the infestation if you can otherwise manage the adults flying around.

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