When it comes to insects in your home, sewer gnats can definitely be considered harmless, but that doesn’t make them any less irritating. Sewer gnats keep their nests inside of your sewer pipes, and they can be really difficult to get rid of. Even pouring bleach or boiling water down the drain usually doesn’t work. This is because they won’t remove the nest with eggs and larvae in them, leaving the next generation of sewer gnats alive. The only way to completely remove all traces of them is with a mechanical cleaning of your pipes.
Sometimes sewer gnats are mistaken for fruit flies, but there are several ways in which they differ.
Sewer gnats have dark, opaque wings, and they have a more triangular shape, similar to moths. They also leave behind a gray powder when you swat at them. Sewer gnats are usually found in areas around sinks and drains, while fruit flies prefer areas around the garbage, your fruit bowl, and similar places.