“What is it in the bathroom (live, ~8-10 mm)? Best regards,” is all this reader writes in his submission regarding the black, worm-like creature pictured below. Although our reader does not give a lot of context surrounding the worm’s discovery, knowing the location it was found in, and seeing what it looks like, leads us to believe that this is a drain fly larva. Commonly known also as sewage flies, sink flies, filter flies and moth flies (due to the adult insect’s stout furry body), drain fly larvae are common household pests that show up near people’s drains, hence the name.