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Extension > Garden > Diagnose a problem > What insect is this? > Insects found indoors > Winged Insects - Less than 1/4 inch long > Moth flies (also called drain flies)

Moth flies (drain flies)



Jeff Hahn, University of Minnesota


Joseph Berger,

Size: 1/12 inch long

Description: Dark colored and hairy; pointed wings held roof-like over the body (they can also be held flat); wings with many parallel longitudinal veins; moderate length antennae.

Where/When: Moth flies are found indoors, especially in bathrooms, kitchens, and other rooms with drains. They can also be associated with sewer breaks. They can be active anytime during the year.

Significance: Moth flies are primarily a nuisance because they can occur in large numbers. They are generally not considered a health problem; however, since they breed in drains, they could potentially transmit disease-causing bacteria mechanically.

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