Sounds like a psycoda sp.- the " moth like fly" is a dead give-away. These don't usually cause too many problems ( except that they'll fly right up your nose- first time I saw them, they were being referred to as "nose flys").

There's about a bazillion sub-specia.

Pyrethrins will kill the adults as they emerge. The larval stages are pretty damned indestructible, as they're well insconced in the root zone.

Just put up with them for now- when you harvest, dispose of all root tissue outside of your dwelling and pyre-bomb the room.

If it is a psychodid,( google "psychoda" for images), suggests that you may have something else going on- food source is decaying organic material.

Do you have a sewage treatment plant nearby? Psychodids are considered to be beneficial in that trade, and may be endemic.

Seriously, look @ on-line images- if you have a match, don't worry about it- they're annoying as all get out, but do little actual damage. Do figure out why you have root zone decay- if they're psychoda, then that's what they're feeding on. Adults do not feed ( at least in any of the specia that I've encountered), so eliminating the food source should take care of the problem.

Oh, and if the images do match, have a look at your sink and shower drains ...ya may have more.