We recently received a short message and a photograph from one of our readers. She explained that she found a few dozen worm-like organisms in her toilet. This is the first time she has ever seen these creatures, so it isn’t a recurring event. She would like to know what they are and how she can get rid of them. The photograph is taken pretty far from the creatures, but we can see that they are small, thin, and black:

We are confident that our reader has discovered drain fly larvae in her toilet. Drain fly larvae are common household pests. These larvae live in the gelatinous film inside a drain or pipe. Drain fly larvae eat decaying organic matter and sewage, which makes a toilet a good home for these larvae. Although the presence of these creatures is not ideal, there is some good news. Drain fly larvae are relatively easy to get rid of and they don’t transmit any human diseases (they are harmless!)

Saying goodbye to these larvae will just require cleaning to make the toilet less hospitable. Our reader should use a cleaning agent that is designed to kill organic matter and a pipe brush to scrub out her toilet. She should be thorough while cleaning to ensure she removes all potential food sources for these larvae. Adult drain flies lay eggs in the gelatinous film that the larvae will eventually eat. So as long as this grime is removed, there will be no place for adults to lay eggs and nothing for the larvae to feed on, which will mean no more drain fly larvae!

In summary, one of our readers discovered some small black worms in her toilet. We believe she found drain fly larvae, which are easily removed by cleaning!