Little silver-winged flying bugs in my drain.... what are they?

[DavidTu]

Well the subject gives the description... I can take and post a photo if needed... anyway, at this point I've had to remove the main stack completely down to the foundation floor to clear out debris at the bottom of the drain (yes, I had to reach down there!) and now I notice that there are these little bugs flying around and walking on the remaining pipe below, going to the sewer. Are these things anything to worry about? What are they? How to get rid of them?

(They're smaller than a fly, bigger than a knat and have silvery wings that fold up like a windsurfing sail.)

Thanks!

[Redwood]

They are referred to as filter flies, drain flies or, sewer flies.

They can be difficult to control... Google "Filter Fly"

Usually they are an indicator of a dried out trap or other breech of the drain and vent system of your home.

[DavidTu]

Usually they are an indicator of a dried out trap or other breech of the drain and vent system of your home.

Thanks for ID'ing these for me! In this case I am seeing them right at the point where the building drain exits the foundation... basically there is a cast iron hub right at floor-level and nothing above it... so there is no trap, obviously, between that and the sewer. Given this does it imply there is a breech in the sewer or pipe leading from sewer to the foundation or were you assuming I was seeing these "upstream" in the drainage system?

[Redwood]

Oh I'm sorry I misread your post...
I guess you could say If you have cut the pipe and it is open you have a breech in the drain...

It would be quite normal for them to be inside of a sewer pipe.

Usually traps on fixtures keep them at bay....

[DavidTu]

Thanks for clarifying Redwood... so sounds like don't have to do anything on it. However, once the plumbing system is reattached it will be a while before we have filled traps... so I am wondering if anyone recommends the product "Invade Hot Spot" (http://store.doyourownpestcontrol.com/product.aspx?iid=23) or another product that would keep them at bay meanwhile?

[MACPLUMB 777]

Go whole "hog" and spend $5.00 or so at the box store and put in a sewer plug like real

plumbers do all the time while working on remodel ! !