# Drain Flies



## Electric_Andy (12 Apr 2022)

I've had what I think are drain flies for several weeks now; tiny little things a bit like midges. They seem to be coming up through the bath (there are a few dead ones in the bathtub). But I've never seen any coming out of any other drains in the house. But, they all seem to go to my downstairs window, I killed about 15 of them yesterday that were around the window.

I've dumped a load of bicarb and vinegar down every drain, but it hasn't worked. If anything, there are more of them now. I inspected the drain outlet outside (looks like 3 x 4" pipes, I assume one for bathroom, one for toilet, one for kitchen sink?) 

I've ordered a pressure washer attachment with a backward facing spray head.

Any other ideas? Could they be coming from anywhere else, or could they in fact be a different type of fly? I don't know how so many are coming through the bathtub upstairs yet congregating downstairs in the kitchen and lounge?


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## classic33 (12 Apr 2022)

Quick search says pour boiling water down the drains, 1-2 times a day for a week.

https://www.thisoldhouse.com/pest-control/21339927/how-to-get-rid-of-drain-flies


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## presta (12 Apr 2022)

You learn something new every day, I'd never heard of them.


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## Cycleops (12 Apr 2022)

I had a problem with these in a shower tray as it didn’t have a proper trap. There was water collecting, I installed one and the problem stopped. 
They will come if there is standing water somewhere so check that and there is a proper trap.


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## Electric_Andy (12 Apr 2022)

Thanks. That is what I can't understand, there is no visible standing water anywhere. It could be becasue I'm often away from the house for a couple days so maybe that gives them chance to breed in the drains. I will try the frequent boiling water trick though


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## classic33 (12 Apr 2022)

The water will be in the traps, with any "biological matter" on the water surface and inside the traps.


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## dave r (12 Apr 2022)

presta said:


> You learn something new every day, I'd never heard of them.



I hadn't heard of them before either, we get fungus gnats sometimes, little tiny flies like midges, the eggs are laid in the compost in our house plants and the larvae live in the compost before becoming flies.


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## Electric_Andy (12 Apr 2022)

dave r said:


> I hadn't heard of them before either, we get fungus gnats sometimes, little tiny flies like midges, the eggs are laid in the compost in our house plants and the larvae live in the compost before becoming flies.


Oh, maybe I'll check my plants too. All my plants are near the window where most of the flies are


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## dave r (12 Apr 2022)

Electric_Andy said:


> Oh, maybe I'll check my plants too. All my plants are near the window where most of the flies are



https://www.rhs.org.uk/biodiversity/fungus-gnats


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## Arrowfoot (12 Apr 2022)

Cycleops said:


> I had a problem with these in a shower tray as it didn’t have a proper trap. There was water collecting, I installed one and the problem stopped.
> They will come if there is standing water somewhere so check that and there is a proper trap.


I am with you on standing water. Had it my shower and I suspect the hot/cold shower temp seem attractive. The trap always has water. From shower it heads out. Bicarb - vinegar did not work. Hot water did not work. Amazingly frequent spraying of ordinary pest can stuff broke the cycle.


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## DRM (12 Apr 2022)

We used to get them at a place I worked at, the business next door was a foundry and it was when the sand from the casting moulds was blocking the drains, they got the drain people in to clear the drains out, and all was well till next time


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## Electric_Andy (25 Apr 2022)

Electric_Andy said:


> Oh, maybe I'll check my plants too. All my plants are near the window where most of the flies are





dave r said:


> https://www.rhs.org.uk/biodiversity/fungus-gnats



Well @dave r you were right. I had no standing water but washed and checked all the drains thoroughly. After washing through with vinegar and bicarb, the little beggars where still flying around the house; more than before if anything. So I re-potted my (5) houseplants and hey presto I haven't seen another fly since. My partner has exactly the same problem so will be re-potting hers too. At least our drains are now clean anyway


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## Electric_Andy (25 Jul 2022)

Bit of an update. The flies came back after I re-potted my house plants. Same thing happened with my partner's plants. Then we realised we'd re-potted with the same cheap compost we'd used before (from The Range or Lidl I think). So we bought some more from a garden centre, I've now re-potted again and kept the plants out in the garage. The flies have completely gone from the house now, so I'm going to leave it another couple of days and bring the plants in. I hope I don't go out to find the garage full of flies too! If that happens then I'm replaceing plants with ornaments


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## dave r (25 Jul 2022)

Electric_Andy said:


> Bit of an update. The flies came back after I re-potted my house plants. Same thing happened with my partner's plants. Then we realised we'd re-potted with the same cheap compost we'd used before (from The Range or Lidl I think). So we bought some more from a garden centre, I've now re-potted again and kept the plants out in the garage. The flies have completely gone from the house now, so I'm going to leave it another couple of days and bring the plants in. I hope I don't go out to find the garage full of flies too! If that happens then I'm replaceing plants with ornaments



Mine came back as well.  persistent buggers, I haven't seen any since I left the Spider plant without water for a month.

Edit, I've just looked at the plant and there's a few dead ones under the plant on the tray, but no bodies elsewhere and none flying about.


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## Electric_Andy (26 Jul 2022)

dave r said:


> I left the Spider plant without water for a month



Yes they do say keeping the plant drier helps break the cycle of larvae. But I couldn't do that to mine because they started to wilt and go brown (Elephants ears, peace lilly, christmas cactus and dragon tree). Fingers crossed the change to larvae-free compost has worked


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