Drain flies are small and gray. They do not bite, sting, or spread diseases, but their decaying bodies may cause allergic reactions. They can also spread bacteria from trash, decaying vegetables and fruits.
Drain flies breed in areas that are moist and have a lot of organic remains, including:
Drain flies can enter homes from drainpipe openings. Adults live for two to three weeks.
To control drain flies, you need to get rid of their breeding site. To find a breeding site, place a clear plastic disposable cup on the openings of all the drainpipes in your home. The adults will collect in the cup if the opening is infested. Pouring hot water down the drain into their breeding site may provide short-term control.
To prevent drain flies, clean your drainpipes each week. Use wooden sticks that have flagged margins or a stiff brush to remove slimy, gelatinous material and hair plugs from the drains. You can also use a bacterial digester to stop the formation of gelatinous material. Finally, use a plumber’s rod to clean up to two feet of the drain.
If you are unable to control an infestation, contact an exterminator or a plumber.