Signs
for Drain Fly
The first sign is the flies themselves — small fuzzy adults on bathroom or kitchen walls, on tub surfaces, or drawn to lights. Their appearance usually means a slow or clogged drain has built up enough organic slime to feed a brood. 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