Pour vegetable or olive oil in your kitchen sink. This will catch any gnats that hang around the drain or garbage disposal. The gnats will fly into the oil but will be either unable to free themselves from it, or simply unable to mate afterward, as they are coated in the oil. You may need to repeat this process several times to get all of the gnats, but it is very effective.
Today the guy who sprays my house was here. I told him I had a lot of what looked like gnats, but there was no food out. He said: buy a bottle of degreaser and pour it for sure in both your kitchen sink drain before you go to bed. Then in the morning before you put any water down the drain pour very hot water in each drain. Gnats fly down to the gunk in your J pipe lay their eggs and a new crop hatches over night. Repeat nightly until your gnat problem is gone.
The gnats you see in and around your drain could be one of many different small flies. Fungus gnats, for example, typically breed in soggy soil in container plants. Fruit flies are drawn by ripening fruit and the recycling bin. Drain flies begin in the sewers and emerge from the drain into the home. These species of small flies and other gnats can...
Our trick for getting rid of fruit flies is simple: put three drops of dish soap (whatever kind you use) into 1 cup of vinegar and leave it out in a bowl. The vinegar will attract the flies to the bowl and the soap will reduce the surface tension so the flies sink to the bottom.