I am beside myself with this problem, they are either drain or moth flies, but they are coming into my home from all over, through the screens, windows, dryer vents, window air conditioners...this has been going on for 3 years now, and i am on my last nerve. they are litterally running me crazy, i cry all the time, because they won't go away. me and my husband took up our mulch, caulked everything, but no matter what we do they don't stop. this is in the front and back of our home. what can we do!!!!!
You must get a positive identification as to specifically what they are. Catch some and take them to a county extension office, agricultural office, etc. Here in Pa. it would be an extension of Penn State.
If they have already been identified as moth or drain flies, also know as sewer flies (psychoda), then you have a drain or sewage problem. These flies indicate a broken pipe, slow or clogged drains. Could be broken right outside the house, since you say the come in from outside, which is unusual.
Search "psychoda" on internet. If this is what you have, then forget about caulking, mulch, etc. You may have a serious septic/sewage problem. Could be right outside foundation wall, or under a slab. Lets us know what you find out, but get a positive ID first, then we have a direction to go. What part of the country are you in?