Elimnation

• 1). Eliminate the source. Find out where the gnats are coming from, and remove the source. If the flies have laid eggs in the soil of a plant, remove the plant. If the gnats appear to be coming from an outdoor garden or crop, try picking the fruit early, or planting between the gnat's life cycle.
  
  
• 2). Surround your crop or garden with poisonous border plants. The fungus-eating fruit flies will eat the roots. This will not only kill the adult gnat, but the effect will also be passed on to the larvae.
  
  
• 3). Clean the house. The gnats are attracted to rotting food as well to as fruit and plants. Dirty dishes left in the sink or old food left sitting out on plates can draw them. Go through the house, and make sure all sources of rotting food are gone. Clean up, and run the garbage disposal as well.
  
  
• 4). Fill a glass half-way with orange juice or vinegar, and let it sit out over night in a place where the gnats are often found. The gnats will be attracted to the acidity, and climb in to eat. They will not be able to climb out, and in the morning, the glass will be full of dead gnats. Repeat this process until all of the gnats are gone.