Anybody ever have to deal with the little gnats that come out of your sink drain? I need some advice.

They’re not fruit flies. I have apples in the kitchen and they have not one gnat flying around them. For that matter, I’ve not seen any of these little flying critters except in my bathroom. They are centered around my bathroom sink, and it is driving me crazy. Right now I have the drain closed, and a piece of tape over the overflow hole so that no more can come up. I put a couple traps out on the sink ledge but I’m still seeing some around. I also poured some boiling water down the drain about an hour ago, and it did seem to help, but I can’t be doing that around the clock.

I know that the people living in the apartment below me had some water damage and I’m thinking that maybe maintenance did not clean up properly from that. Also, I think the people may have moved out as of yesterday and I don’t know if they left a mess. I can let maintenance know tomorrow, but I hate having them having to come into my apartment if it’s something I can handle on my own. But I’ve never once had gnats in the year that I’ve lived here so I’m thinking this is coming from somebody else’s apartment.