To eliminate drain flies, identify the area where the flies are breeding, and clean the affected pipe. Repairs may be necessary if the flies are breeding near a damaged drainage pipe. Eliminating a drain-fly infestation may require several days to allow time to locate the source of the infestation.
- Identify the affected drains
To identify the specific location of drain fly larvae within the home, coat the inside of a disposable cup with petroleum jelly, and place the cup over the drains in the affected area for 24 hours. If the flies are present inside the cup, the drain is infested. Examine the home's plumbing system for leaks, which attract drain flies.
- Clean the affected pipes
To eliminate drain fly larvae, remove the drain covers in the affected areas of the home, and scrub the drain pipe with a firm brush and household cleaner. Bends in the pipe, such as J-shaped traps, should be removed and thoroughly cleaned. Snake slow-draining pipes to remove debris before cleaning. Repair leaks in water or sewage lines as needed.
- Use an enzymatic cleaner
To prevent the buildup that causes drain flies, use an enzymatic cleaner that is designed to clean drain pipes on a regular basis.