A reader found a worm-like organism in her toilet. She photographed it on the side of a toilet paper roll so we can visualize the size of the specimen. It is black, long, and thin. So, what is this specimen?

We often hear about two creatures found in toilets: Bloodworms (midge fly larvae) and earthworms. Bloodworms are bright red, small little creatures that inhabit bodies of water. Earthworms are annelid worms that live in wet soil and require moisture for survival. They have segmented bodies that range from purple to brown. However, the worm featured in the photograph our reader sent isn’t red, or brown/purple. So, what did she find in her toilet?

We think it is very likely that the specimen is a drain fly larva. While we can’t make out very much detail in the photo, it roughly resembles the general shape and size of a drain fly larva. Also, a toilet is a likely environment to find a drain fly larva in since drain fly larvae feed on organic matter and sewage.

Female adult drain flies lay their eggs in most places that decomposing organic materials are found. The best way to control the presence of drain flies and their larvae is to remove the breeding site, which is the organic matter lining the drain. In other words, she needs to physically clean out her toilet using a brush and cleaning product. She should purchase a product that is designed to destroy organic material, and scrub until she is confident all the potential breeding site and food source is gone.

In summary, we think our reader found a drain fly larva in her toilet. She will need to thoroughly clean her toilet to get rid of these creatures. In the mean time, she shouldn’t stress about the presence of these specimens because drain fly larvae aren’t known to transmit any diseases to humans.