As with most pest problems, proper identification is as important or more important than the actual treatment. Identifying the type of gnat will direct us on where to look for their breeding sites. It may require anything from new caulk around the tub, deep cleaning a drain or pantry, dehumidifying a garage, or even locating a deposit of organic material from a leaking drain. Without eliminating the source of the problem, it can only be managed rather than eliminated. We liken it to bailing water from a boat without ever plugging the leak.
Are they inside or outside the house, if they are inside the house the are most likely fruit flies. Best thing to do in this case is to find the source it could be fruit, an old wine bottle or the funky stuff that gets caught in a sliding window. Find the source and clean it up and them most of the time the problem is solved.
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