Drain flies do not bite or sting. But their presence can become a nuisance because of their large populations. [pic source]
Drain flies reproduce in polluted, shallow water or highly moist organic solids. The eggs, larvae and pupae can be found in the muck, slime, or sticky film often accumulating on the sides of drains and overflow pipes in homes, or in sewage disposal beds, septic tanks and moist compost. They have also been found in dirty garbage containers, rain barrels and tree holes
Drain flies sometimes appear suddenly and mysteriously, becoming a nuisance in homes. Adult flies may become so numerous indoors that they congregate at windows, darken lamp shades at night, fall into food and accumulate around showers, bathtubs, sinks and floor drains, especially in the basement.
- Tips For Control:
Alternative recommendations include cleaning pipes and traps with a good, stiff, long-handled brush.