How to Bug Proof Your Home: Moth Flies (Drain flies)

Pest Management In and Around Structures October 18, 2011 Print Friendly and PDF
Moth Fly (Drain fly)
Joseph Berger,


Moth flies are named because their furry wings and feathery antennae make them look like miniature moths; however, they are actually a unique group of small flies. They are also known as drain flies, filter flies, and sewage flies, named after the breeding sites in which they reside.

These breeding sites consist of rich organic decaying material. In the urban environment, they are commonly found in clogged roof gutters, under potted plants, in garbage cans, around septic tanks, in moist compost, and poorly cleaned drains, particularly in outflow pipes of toilets and sinks.



  1. Unused sewage pipes must be cleaned and capped off.
  2. Clogged sink overflows must be cleaned. Use an enzymatic drain cleaner followed by very hot water, and if necessary by manual cleaning with a stiff brush. Bacterial or enzymatic cleaners are effective. Some cleaners contain live, beneficial bacteria that destroy organic material inside the drains, removing the habitat in which the moth flies breed.
  3. Water leaks must be fixed along with any other moisture problems around the home.
  4. Ensure your compost bin is a dry environment. Scatter moist compost around the bin to dry it out faster.
  5. Regularly clean out roof gutters.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.