Drain flies are poor fliers and are commonly seen walking or running along walls and other resting surfaces. The drain fly’s flight only covers a few feet. The flight is short with jerky lines. Most of their activity is at night, where they are seen hovering about sinks and drains.

It is necessary to inspect for breeding sites and remove them. There are many potential areas that serve as breeding sites for the flies. Removing the breeding site is the most important part of a drain fly control program.