Moth fly


Hope everyone had a great holidays! I’m a little late with this week’s post as a result of my own. I’m digging back into the archives again for this one. I spent some time this fall helping my sister and her boyfriend out with a bit of house and yard work. I happened across this little guy while scraping old paint from exterior trim; he was sitting right next to the frame so I wouldn’t miss him.

It’s a moth fly, a member of the family Psychodidae, a group of flies whose hairy bodies and long antennae give them the look of moths. I was absolutely delighted by this find; I’d seen the photos of moth flies in my Kaufman Field Guide to Insects and kept watching for one, unsuccessfully.

Moth flies are pretty small, only a 1/4″ (1/2 cm) long at most (some are only a third that length). They favour wet habitats, and apparently can become nuisance pests in kitchens, where their preference for sink pipes lends them another of their common names, drain flies. The larvae eat algae and bacteria that are growing in the damp environment of the drainpipe (or other more natural situations); adults are nectar-feeders. Because they utilize habitats in human homes, they can be encountered at any time of year.


There are 113 species in North America, but some 3000 worldwide. A particular subfamily are blood-suckers and can transmit diseases, but the ones found in your home are generally harmless. In fact, the larvae of some moth fly species are actually useful and important in the purification process of sewage treatment plants.

I’m pretty sure this one is Clogmia albipunctata, for which BugGuide gives the common name Filter Fly. BugGuide notes that the species used to be primarily tropical but is now found through much of North America.


Author: Seabrooke

Author of Peterson Field Guide to Moths. #WriteOnCon Mastermind. Writer of action/thriller SF/F YA. Story junkie. Nature nut. Tea addict. Mother. Finding happiness in the little things. Twitter: @SeabrookeN / @SeabrookeLeckie

4 thoughts on “Moth fly”

  1. Oh, yes, I get them in the bathroom here — mostly during winter when it’s dry. I suspect in summer it’s soooo wet, they don’t need to be inside.

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