I've successfully dealt with them for years with Tanglefoot / Tangle-Trap.
Sticky goop that attracts them - they land on it - and are stuck!
Brush it onto 2 or 3 inch squares of paper or cardboard
and place
around your indoor plants. When the card is 'full' -
toss it away and replace it with a new one.
I learned about the stuff from my dad. He used to propagate azalea and
rhododendron cuttings, forsythia, day-lillies, et-cetera in his garage.
The fungus gnats were a problem until he started using this tangle stuff.
May God Bless my dad's green-thumbed soul - he would be 96 now!
