Drain Fly (Moth Fly)

Where it lives

Gelatinous organic film inside drains, shower traps, floor gullies, sewage pumping chambers, air conditioning condensate trays and septic tanks.

Signs

• Small furry moth-like flies resting on bathroom and kitchen walls
• Flies emerging when a rarely used shower or gully is run
• Numbers concentrated in a single room or around one drain
• Slow-draining or odorous waste pipes

Risks

• Can mechanically transfer bacteria from sewage film to surfaces
• Persistent nuisance in bathrooms, spas and commercial washrooms
• Indicates a drainage fault that may lead to a worse problem

Prevention

• Run water through every drain and gully weekly, including guest bathrooms
• Clean hair and soap build-up from shower traps
• Service air conditioning condensate trays
• Repair cracked or blocked waste pipework
• Avoid pouring bleach as a “fix”. It does not touch the organic film

Treatment

We identify the exact drain with sticky traps placed over each outlet overnight, then apply a bio-enzyme foam that clears the biofilm the larvae live in, followed by a residual treatment around the outlet. Where a broken pipe or dry trap is the cause we report it so the underlying defect can be repaired.