# Drain Flies from pipe in Sump Pump Area

We've been in our home for two years now. For the first year, we were fine, but this year, we've had record rainfall and billions of drain flies since late February. We didn't know where they were coming from at first, but now we know where... the pipe where the sump pump is located. This is the sump pump and the black pipe that all the drain flies are coming from (located in the storage closet under the stairs of the walkout basement). Please see attached image. If it weren't for the fly strips and the light bulb, those thousands of flies would be all over our house... right now they are contained in the closet but not dying despite pouring about 5 gallons of bleach down there and 16 oz. of Invade Bio-Foam. The flies are not in the sump pump itself but they are coming in from the rain water drain off pipe (the black one) that comes into the house; the water drains off into the sump pump area where the pump takes it out of the house through another pipe. So the black pipe is where it's coming from. The pipe itself is clean up to what my husband could reach. He even ran a 25 foot snake down there and still nothing. I would really appreciate any help or suggestions you could give us. We didn't have this problem last year, but we didn't have the record rainfall either. What can we do? As you can see, it is really gross! Help! Oh, and we are on City Utilities, not a septic tank. We have called five different pest control places who won't touch it (either told us to pour bleach or keep doing what we are doing), one plumber who cleaned sewer lines but told us to call pest control, and an online seller of DYI pest control. We just need some help:(.

Last edited by Val08; Jul 16, 2008 at 09:12 PM.
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 hkstroud Posts: 11,867, Reputation: 891 Home Improvement & Construction Expert #2 Jul 16, 2008, 08:52 PM
Is enough of the pipe expose so that you could install a trap?
 Val08 Posts: 7, Reputation: 1 New Member #3 Jul 16, 2008, 09:10 PM
The pipe is exposed but we can't get to all of it (that's the sticky fly trap you see there in the photo covered in flies!) We have to change the fly strips every week because they are so covered that there is literally no stick to them. Oh, I forgot to mention that we called five different pest control places who won't touch it (either told us to pour bleach or keep doing what we are doing), one plumber who cleaned sewer lines but told us to call pest control, and an online seller of DYI pest control. We just need some help:(.
 hkstroud Posts: 11,867, Reputation: 891 Home Improvement & Construction Expert #4 Jul 16, 2008, 09:41 PM
This is just a suggestion but I don't know if its doable because of the lack of room.
That looks like 6" corrugated drainage pipe. Get some 4' PVC pipe and a 90 degree ell. Can be Schedule 40 or thin wall. Cut one piece long enough to go up in the drain pipe a foot or so. Put that inside the drain pipe and put on the 90 degree ell. Add another piece of pipe long enough to reach about 1" above the bottom of the sump crock or hole. You want the end of the pipe to be below the water level that is left after the sump pump shuts off and far enough from the bottom to let the water out. Reset the float level of the pump if necessary. You will probably have to temporarily remove the pump to do this. Seal between the PVC pipe and the drainage pipe. Use cloths or even those large sponges. Anything to block the opening, it doesn't matter if it gets wet. You are not trying to seal for water, just seal out the insects. With the end of the PVC pipe below the water level they should not be able to enter. You should not even have to glue the pipe together.
 speedball1 Posts: 29,303, Reputation: 1939 Eternal Plumber #5 Jul 17, 2008, 10:19 AM

I had drain flies in my shower so I realize what you're going through. A trap or bleach won't stop them. The following may help.

MOTH OR DRAIN FLIES

Moth or drain flies are small black flies which
Thrive in drain pipes and sewer lines. They need
A lot of moisture to complete their life cycle.
Drain flies do not fly well. They tend to drift
And seem to float along more than fly. Their
Wings are shaped like a leaf of a plant and one
Can see hair like fibers on all parts of their
Body which is why they are also called moth flies.
I have dealt with drain fly infestations in
Many homes which start in the sink or bathroom
Shower. The drain lines which have the most
Activity seem to be the ones most likely to have
An infestation. I have also observed that homes
With septic tanks seem most likely to get them.
I am not sure if there is some kind of build up
Which occurs more with this type of drainage
Or if there is something in the tank which allows
These flies to prosper. Although these homes
Seem more likely to get drain flies, once the
Cycle begins it takes place in the home. I have
Encountered several infestations where the larva
Were found crawling out of shower or bath tub
Drains. The homeowners thought they were some
Kind of leach. In fact, the larva of drain flies
thrive in a slime buildup which is on virtually
any drain pipe which is used a lot. This slime
enables the eggs which are laid to be protected
and sheltered. The eggs and hatching larva
embed themselves in this slime so they don't wash
away. The cycle of these flies takes around
a month to complete. Don't waste your time with
bleach or other cleaning solvents.
Showers and tubs
Which have ceramic tiles may also supply a moist
Slimy environment in which they can live. Sump
Pumps and wet crawl spaces are other environments
Where I have seen them live. Drain flies can be harder
To control than other small flies. Although
There are several products to kill adults, the
Key is maintaining and minimizing their breeding
Areas. This could prove to be difficult and
Ongoing.
Like most flies, there are several products
Available for their control. Use a "SPACE SPRAY"
For immediate relief of the adults. There are
Several to choose from in the section below.
This will quickly control the adults, but the
Secret to getting rid of them is to use a
Product we sell which removes the slime build
Up on drain pipes. By removing this slime, the
Larva cannot develop. This will stop the cycle.
In the "SURFACE SPRAY" section below, look for
The product called SURVIVORS. This is applied
Down drain pipes and will remove the nest sights
These flies need. You may also use the product
Called PT-CYKICK which is located in the same
Section. It is ideal for treating in cracks and
Crevices where these flies like to lay eggs. Such
Cracks will develop around ceramic tile, windows
And grout joints.
Good luck, Tom
 Val08 Posts: 7, Reputation: 1 New Member #6 Jul 17, 2008, 07:03 PM
Thank you everyone! I really appreciate the expertise!:)
 lamereee Posts: 2, Reputation: 1 New Member #7 Jul 15, 2009, 06:24 AM
I notice that you posted this a year ago. I hope that by now you have found an answer to your problem. However if you have not, this might help. We are having a similar problem as you have/had. We have been in our house for 6 years and this is the first time we have had an issue with flies in our sump pump. Also like you, I have called every pest control business in town and no one would help me. The last place I called said, "You don't need me. All you need is cooking oil." He told me to pour cooking oil down my sump pump. It lies on top of the water and coats the pipe and also covers the eggs of the flies not letting them breath and therefore die. We only did this yesterday and I'm not ready to say we are fly free, but I do see an improvement. Hopefully this is a non issue for you anymore, but if not here's something to try. Good luck (To both of us)!
 speedball1 Posts: 29,303, Reputation: 1939 Eternal Plumber #8 Jul 15, 2009, 06:56 AM

Please let us know if cooking oil will interrupt the cycle. If it works then you've discovered "a miracle cure". Good luck and let us kinow. Tom
 lamereee Posts: 2, Reputation: 1 New Member #9 Jul 15, 2009, 03:52 PM
The cooking oil does not interrupt the cycle. In fact I put the oil on yesterday and early this morning it rained and the sump pump worked fine. I'm hopeful that this solves our problems. It looks good, but we'll have to just wait and see.
 speedball1 Posts: 29,303, Reputation: 1939 Eternal Plumber #10 Jul 15, 2009, 04:02 PM

Originally Posted by lamereee
The cooking oil does not interrupt the cycle. In fact I put the oil on yesterday and early this morning it rained and the sump pump worked fine. I'm hopeful that this solves our problems. It looks good, but we'll have to just wait and see.
I meant the drain fly cycle of breeding. Let us know if it works. There are a lot of people out there that will be interested. Cheers, Tom
 Val08 Posts: 7, Reputation: 1 New Member #11 Jul 16, 2009, 11:45 AM
The drain flies are gone! Okay, not DEAD, but we will never see them again. Our sump pump was improperly installed (we were not the owners at the time of installation), so it was basically an open pit. After a $2,000 plumbing job that placed the whole thing underground, bolted it in, and redirected the water pipes outside, our house is fly free. It was worth every penny... the plumber we hired had 15 years of experience and said he had seen people move because of the flies... they are horrid little devils who just love that high moisture environment and will continue to thrive and reproduce for all of eternity. Oh, I feel for anyone who has this problem. I am so thankful it was a one-shot solution after all we tried! Good luck to you!  rmdobson Posts: 1, Reputation: 1 New Member #12 May 2, 2012, 09:29 AM Originally Posted by hkstroud This is just a suggestion but I don't know if its doable because of the lack of room. That looks like 6" corrugated drainage pipe. Get some 4' PVC pipe and a 90 degree ell. Can be Schedule 40 or thin wall. Cut one piece long enough to go up in the drain pipe a foot or so. Put that inside the drain pipe and put on the 90 degree ell. Add another piece of pipe long enough to reach about 1" above the bottom of the sump crock or hole. You want the end of the pipe to be below the water level that is left after the sump pump shuts off and far enough from the bottom to let the water out. Reset the float level of the pump if necessary. You will probably have to temporarily remove the pump to do this. Seal between the PVC pipe and the drainage pipe. Use cloths or even those large sponges. Anything to block the opening, it doesn't matter if it gets wet. You are not trying to seal for water, just seal out the insects. With the end of the PVC pipe below the water level they should not be able to enter. You should not even have to glue the pipe together. I am going to do what HKStroud suggests. It seems like a permanent solution vs having to keep pouring cooking oil down the sump pit or insecticide. My sump pit is similar. However I must say I have been having good luck filling my basement utility tub with hot water and a bunch of pine oil then letting it go all at once into the sump pit. I can hear the sump pump cycle about 3 or 4 times so I know its working. I think the scalding hot water itself is enough but use the pine oil anyway. hkstroud please send me a private message to discuss. Thanks  speedball1 Posts: 29,303, Reputation: 1939 Eternal Plumber #13 May 2, 2012, 01:57 PM Originally Posted by Val08 The drain flies are gone! Okay, not DEAD, but we will never see them again. Our sump pump was improperly installed (we were not the owners at the time of installation), so it was basically an open pit. After a$2,000 plumbing job that placed the whole thing underground, bolted it in, and redirected the water pipes outside, our house is fly free. It was worth every penny....the plumber we hired had 15 years of experience and said he had seen people move because of the flies...they are horrid little devils who just love that high moisture environment and will continue to thrive and reproduce for all of eternity. Oh, I feel for anyone who has this problem. I am so thankful it was a one-shot solution after all we tried! Good luck to you!
We thank you for the update. I've been infested twice now and have learned that there is no " miracle cure" It takes time and a lot of patience. You must first locate the source and seal it off, Then close off all the drains until used so they can't get down there and lay eggs. ( I used anything that would cover the drain,) Sticky fly strips worked the best after I "bug bombed" both bathrooms. For some reason they're attracted to black coffee with a lot od sugar in the cup. They just fly in and drown. Good luck, Tom

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