Biology
for Drain Fly
Drain flies undergo complete metamorphosis — egg, larva, pupa, adult. A female lays a cluster of eggs (a few dozen up to about a hundred) in the wet organic film, and they hatch within a day or two into slender, legless larvae. 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 Source: https://cfaes.osu.edu/fact-sheet/drain-flies-moth-flies The larval stage is the long one (roughly nine to fifteen days); a brief pupal stage then yields the adult. Estimates of the full cycle range from one to three weeks (Ohio State) to about three to four weeks (UF/IFAS). Source: https://cfaes.osu.edu/fact-sheet/drain-flies-moth-flies Source: https://ask.ifas.ufl.edu/publication/IN1226