# Need help with Drain flies coming from under concrete slab/foundation with no access



## Nik333 (Mar 1, 2015)

I feel your pain. . . they are awful. I'm not a pest guy & hopefully they will be along.

Temporarily, buy a few bags of lemons, cut them & place them where the flies bother you the most. They really help. The science behind it is that the d-limonene in the peel repels them. It works.

Also, fly tape, although unsightly, works well.

I think this will be an up & coming problem since they kill the honeybees that fertilize crops.

I don't have a long-term solution except that the colony living on the wet foundation is where they're from. There are many threads on here about drain flies/phorid flies. The owners seem to spend a fortune on having drains cleaned, with no success.

The house has to be kept spotless as they will even grow in wet coffee grounds, or a tiny puddle of coffee on a sink corner. Kitty litter seems to be a common 
item in these houses.

I got so desperate, at one point, I duct-taped around the crooked steel doors. I should have put cut lemons around the doors.

Good luck!


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## motosonic (Jun 3, 2019)

Thank you for the advice!
Lemons.. Hmm, I have not seen that suggestion online yet. I've heard everything from water/sugar/vinegar/dish soap(which doesn't work AT ALL) to bleach.

My hope.. Is that eventually that ground will dry out and the flies will lose their breeding ground. It was very saturated and they sucked out as much of the grey water as they could reach/find with a massive vac truck.. but, clearly they missed some. 

We've been meticulously cleaning around the house to get rid of any additional breeding grounds they may be creating once they get inside.

I do NOT want to pay to have that slab opened up again because this whole process cost me a fortune.. of which I do not have. I can't afford any more huge bills.


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## MTN REMODEL LLC (Sep 11, 2010)

I will be interested in what some of our pest control ideas are...... 

but have you tried just an Ortho or Spectracide treatment around your interior and exterior perimeter....?????


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## Nik333 (Mar 1, 2015)

The d- limonene has actual science behind it. I didn't try orange peels. Once the volatile oil evaporates?, you need to cut new lemons. They were good for several days each in my humid home. The oil can be bought, also.

Btw, after battling this for months, the city stated they needed to replace the city's leaking sewer pipes! So there was not only leaking pipes onto the slab but leaking sewage in the area. We had corpse flies, too.


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## Nik333 (Mar 1, 2015)

I also just realized that where I feed feral cats & TNR, there are lemon & grapefruit trees all around where I sit. There are no flies! Ants & cockroaches, yes, but no flies. It's 90 degrees in the day.


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## motosonic (Jun 3, 2019)

MTN REMODEL LLC said:


> I will be interested in what some of our pest control ideas are......
> 
> but have you tried just an Ortho or Spectracide treatment around your interior and exterior perimeter....?????


I spoke with some folks at Terminix and they said the spraying won't help unless we can get rid of where they're breeding.


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## MTN REMODEL LLC (Sep 11, 2010)

motosonic said:


> I spoke with some folks at Terminix and they said the spraying won't help unless we can get rid of where they're breeding.



I sure am no pest control specialist... but any chance of injecting a proper fly killer directly through a 1/2 hole drilled above where the sewage crap/breeding ground is likely to be.

That is the method with subteranian termites on slab foundations...should not be that expensive....just drilling a couple of 1/2 holes in the slab...and pest control has a wand with a rubber tip ...and stands there while injecting under some pressure.....

.... or southern engineer it and use a garden hose and a tree root feeder.:wink2:


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## motosonic (Jun 3, 2019)

MTN REMODEL LLC said:


> I sure am no pest control specialist... but any chance of injecting a proper fly killer directly through a 1/2 hole drilled above where the sewage crap/breeding ground is likely to be.
> 
> That is the method with subteranian termites on slab foundations...should not be that expensive....just drilling a couple of 1/2 holes in the slab...and pest control has a wand with a rubber tip ...and stands there while injecting under some pressure.....
> 
> .... or southern engineer it and use a garden hose and a tree root feeder.:wink2:


You know this might not be a bad idea!! I can ask and see!!


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## PestGuy (Jan 15, 2018)

motosonic said:


> but they're still coming into the home from what looks like the space between wall/floor, and under the slab.


Is this a space that you can caulk or seal off somehow to stop them from getting in?


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## motosonic (Jun 3, 2019)

PestGuy said:


> Is this a space that you can caulk or seal off somehow to stop them from getting in?


A few folks have asked this. Not from what I can see "yet". There's still drywall in the way, so.. we're supposed to have a contractor in to 'fix' all the mess created by this sewer line failure.. I'm going to see if we can tear down/rebuild the drywall so we can look for cracks (and seal them all up). This is a good idea
thank you


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## DoomsDave (Dec 6, 2018)

@motosonic, can you get a good, close up picture of the flies? It's crucial to ID them properly to do a real job of eliminating or at least controlling them. Otherwise you'll be doing a band-aid when you might need surgery, so to speak.

If you can't get a picture, can you find a picture of what they look like online and show us?

That will help hugely.


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## motosonic (Jun 3, 2019)

DoomsDave said:


> @motosonic, can you get a good, close up picture of the flies? It's crucial to ID them properly to do a real job of eliminating or at least controlling them. Otherwise you'll be doing a band-aid when you might need surgery, so to speak.
> 
> If you can't get a picture, can you find a picture of what they look like online and show us?
> 
> That will help hugely.


https://www.bobvila.com/articles/how-to-get-rid-of-drain-flies/

These. I've had them ID'd already that's how I know what they are specifically.


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## DoomsDave (Dec 6, 2018)

motosonic said:


> https://www.bobvila.com/articles/how-to-get-rid-of-drain-flies/
> 
> These. I've had them ID'd already that's how I know what they are specifically.


Yes, you've ID'd them correctly. I ask because many people just slap names on things, and they turn out to be something else with a different remedy.


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## motosonic (Jun 3, 2019)

DoomsDave said:


> Yes, you've ID'd them correctly. I ask because many people just slap names on things, and they turn out to be something else with a different remedy.


Thank you!

We've had a couple dry (but cool) days and the #'s have gone down significantly. A good rain or some warming will be able to tell me if our problem is working itself out or not.


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## kmf80 (Sep 19, 2019)

I'm curious to know if your problem cleared up on its own, and if so, how long did it take? I just had a broken drain pipe under slab replaced about a week ago but haven't seen a noticeable reduction in the number of flies yet.


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## KRA (Oct 24, 2019)

I’m curious as well. We had a leak in our kitchen drain line under the slab fixed 3 weeks ago but a new batch of phorid flies have just appeared. I’m wondering if it will just take months to dry out since it had been leaking for over a year?


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## PestGuy (Jan 15, 2018)

Just because the broken pipe has been fixed does not mean the problem may be solved. They could still be breeding in the damp soil under the floor. In cases like this you will most likely need to checkerboard the floor and inject an insecticide properly labeled for such an application, like a termiticide, to kill the breeding site in the soil.


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## KRA (Oct 24, 2019)

Finally got rid of all the phorid flies. There were more breaks in the cast iron drain which weren’t clearly visible on the drain camera. Ended up replacing 30 feet and that did the trick.


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## angsor1 (Jun 20, 2020)

@motosonic and [MENTION=561165]kmf80[/MENTION ], how did it turn out? We’re facing the Same issue. Our slab is opening on Monday and I’m fearing the worse. How did things turn out? We have tons of flies and I’m so worried that because the leak has lasted for so long, It’ll take forever for the flies to go away even though we’re replacing the 15’ pipe under the slab. Looking for positive stories to ease my anxiety. Thank you!


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## angsor1 (Jun 20, 2020)

KRA said:


> Finally got rid of all the phorid flies. There were more breaks in the cast iron drain which weren’t clearly visible on the drain camera. Ended up replacing 30 feet and that did the trick.


. @KRA I find your post very encouraging! Once all the pipes were fixed, the flies stopped coming in despite all the moisture under the slab from months of leaking? Did it just dry over time? I’m seeking any updates or as many details to help ease my anxiety. I’m expecting to see a ton of flies and sludge when they open the slab on Monday and I’m worried that fixing the pipe alone won’t get rid of the flies because of all the sludge under the slab having collected there for many months .... any additional information Or updates would be great. Thanks


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## CathyNj (Mar 15, 2021)

Hi! We have had drain fly problem for 3 years . It goes away when heat is on but as soon as we turn off heat/turn on ac they come back . We are ok slab and 95 percent sure that he where they are coming from. We want to sell in 3 yrs and am concerned we really can not sell during spring /summer . I want to resolve once and for all but how do u identify where the break is ?


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## Tiger927 (Aug 20, 2021)

angsor1 said:


> . @KRA I find your post very encouraging! Once all the pipes were fixed, the flies stopped coming in despite all the moisture under the slab from months of leaking? Did it just dry over time? I’m seeking any updates or as many details to help ease my anxiety. I’m expecting to see a ton of flies and sludge when they open the slab on Monday and I’m worried that fixing the pipe alone won’t get rid of the flies because of all the sludge under the slab having collected there for many months .... any additional information Or updates would be great. Thanks


Did this end up going away on its own without digging up the soil? I've been getting conflicting answers on whether it can go away on its own if a broken sewer line is properly fixed.


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## Jdimarco63123 (10 mo ago)

angsor1 said:


> @motosonic and [MENTION=561165]kmf80[/MENTION ], how did it turn out? We’re facing the Same issue. Our slab is opening on Monday and I’m fearing the worse. How did things turn out? We have tons of flies and I’m so worried that because the leak has lasted for so long, It’ll take forever for the flies to go away even though we’re replacing the 15’ pipe under the slab. Looking for positive stories to ease my anxiety. Thank you!


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## sidearms2055 (4 mo ago)

Going thru this issue right now. Tore up the carpet and wall where there mostly resides. Found where they were coming in from. Little gap where the wall and floor met. Did not know that was an actual opening to the ground. I watched that opening, there was one that came up every 15-30 seconds. Sealed that open with cement calk. Will go all along the wall/floor w/ calk in the basement that I have access. So, does this mean I have a break in the pipes under the slab?


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## chandler48 (Jun 5, 2017)

@sidearms2055 it is always best to start your own thread and refer back to this one if needed. You'll get more responses than you will from a 2 year old thread.


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## sidearms2055 (4 mo ago)

motosonic said:


> A few folks have asked this. Not from what I can see "yet". There's still drywall in the way, so.. we're supposed to have a contractor in to 'fix' all the mess created by this sewer line failure.. I'm going to see if we can tear down/rebuild the drywall so we can look for cracks (and seal them all up). This is a good idea
> thank you


Did you end up tearing down the dry wall and sealing the cracks?


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