After leaving her house in South-East England empty for three months, this reader has found a worm in her toilet and wonders if we have any ideas about what it could be. The worm is described by our reader as having “yellow and reddish-brown stripes”, and zooming in on the photograph she sent us confirms, at the very least, that the worm is striped.
To answer our reader’s question, we do indeed have an idea what this “worm” is. Given the location it was found, its physical description and appearance, as well as the period of time during which our reader was absent from her home, we have identified this worm as a drain fly larva. Often referred to as moth flies, sewer flies or filter flies, the adult drain fly is 1/8-inch in size and fuzzy to the touch. In fact, one of the reasons people call them moth flies is because they mistake them for moths, when they are in fact a species of fly.
Now, drain flies and their larvae are not harmful in any direct way to humans, but can easily infest a bathroom if nothing is done about them. Of course, there is nothing much one can do if one is not home for a long period of time, which is precisely when drain fly larvae tend to move in. As they feed on the decaying organic matter that builds up in drains, they are more likely to be attracted to a bathroom (or kitchen, basement or laundry room) after a long time of neglect. Usually just regularly using any given room with a drain and regularly running the faucets and using the toilet is enough to discourage drain flies from paying the room a visit. But in addition to that, maintaining a consistent cleaning routine is the most important thing in preventing and controlling drain fly infestations.
So, what our reader will want to do immediately is look for any film that would have formed inside the lip of any given drain (as there may be more larvae present than the one she found in her toilet) and clean it out using a bleach-soaked brush or cotton swab. This is where the eggs of the drain fly are laid, and are the source of any drain fly infestation. Of course, that is not to say that our reader is experiencing an infestation, but it is better to be safe than sorry. Then, she will want to clean out her bathroom as she normally would when cleaning it, including pouring bleach down her toilet before flushing and running hot waters from the taps before pouring bleach down those drains as well. She will then want to repeat this routine a few more times than usual for a couple of weeks, to make sure no more organic matter builds up for the larvae to latch onto and feed off. In regard to the larva she found, we recommend that she moves it outside (and any other larvae she might find roaming). They do not tend to wander back into the home, so she needs not worry about this.
To conclude, the worm our reader found in her toilet is a drain fly larva. We hope for her sake that she will only find the one, as infestations of these critters can be quite the nuisance, despite them being — typically — short-lived. We hope that the advice detailed in the article will prove useful to our reader, and that her home is larvae-free soon!