Treatment
for Drain Fly
The target is the larval food source, not the adult fly. At the confirmed breeding drain, mechanically strip the gelatinous film: scrub the opening, pipe, and trap with a stiff, long-handled brush, then flush with boiling water. Source: https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/ENTO/ENTO-414/ENTO-414.pdf Source: https://extensionentomology.tamu.edu/wp-content/uploads/2017/09/Drain-Flies-Publ.-E-184.pdf For buildup a brush can't reach, a biological or enzyme product that digests the slime is an effective non-insecticidal follow-up; harsh chemical cleaners barely help, since larvae shelter inside the film. Source: https://wpcdn.web.wsu.edu/wp-puyallup/uploads/sites/415/2014/12/PNW_PPDrainFlies.pdf Source: https://cfaes.osu.edu/fact-sheet/drain-flies-moth-flies