One of the most annoying, persistent insects I have ever encountered in my life is the gnat. I am still in direct combat with them to this day. One thing that I have seen even make a dent in them is to put out bottles of vinegar near problem areas (like sink drains, trash bins, or anywhere that could be smelly that you see gnats). Take an empty bottle or container and pour in some white vinegar, about 1/4 of the bottle. If you don't have vinegar, beer is a gnat magnet, as well as anything sweet smelling like fruit juice. ( A combination of these really attract the little punks.) Just leave the cap off and they will follow the smell. When you see some of them congregating inside, cap the bottle very quickly and shake vigorously! The little pests will drown inside and you can smile knowing that those guys won't bug you anymore! It also helps to keep the dishes clean and the trash low or taken outside.