A reader recently wrote to us about worms in the toilet. He found worms in the toilet three times, and every time he has found the worms they have been in the toilet (i.e., the worms have been nowhere else in his bathroom or house). Finding worms in your toilet is always mildly concerning, for the fear is that they might have actually come out of your body. However, the reader doesn’t think this is the case because the have always been found before any one has used the toilet, and he has taken the further measure of instructing everyone in his family to check the toilet before and after they use it, a sage approach. In every case, the worm is found before the toilet is used. So, what are these worms in the toilet, and how might our reader get rid of them?

First, the reader sent us this picture:

It’s not the clearest picture, but it does show the worm in question fairly well. We also know from the reader’s email that the worm is about a quarter of an inch long, which is always helpful to know.

It is rare to be certain when working the worm-identification beat, but we are virtually sure the reader found a moth fly larva (or rather, larvae, as he found them on multiple occasions), which we have written about several times because readers find them all the time (simply because they are quite common). Sometimes we are only able to speculate that a reader found moth fly larvae because of the circumstances in which the creatures are found, even though the physical descriptions we are presented with do not perfectly match the larval form of the moth fly (not that they all look alike). However, the creature pictured above clearly looks like moth fly larvae, and our answer is made all the stronger by the place in which they were found.

Moth fly larvae are of course larvae, meaning they are not worms, even though readers almost invariably refer to them as “worms.” As larvae, they are the immature form of the moth fly. If given time to grow into their adult form, which tend to be a dark gray color, our reader will soon find moth flies around his bathroom. Moth flies are attracted to moist places with decaying matter, such as shower and sink drains (so much so that moth flies are often called “drain flies”), as well as toilet bowls. Indeed, a toilet bowl is a perfect place for drain flies to start their reproductive cycle because of the various bacteria and decaying matter, which serve as food sources, found here. This is particularly true if the toilet isn’t used very much, as drain flies especially like stagnant water.

So our reader is probably dealing with moth fly larvae, but how should he get rid of them? If this were a one-time occurrence, the answer might be as simple as “flush the toilet.” However, the larvae keep coming back, so there is likely some contaminant in the toilet that keeps pulling the moth flies in again. As such, the reader should thoroughly clean his toilet bowl and the surrounding area (like the floor beneath the toilet). To do a really thorough job, some type of cleaning agent that kills bacteria could be used. If the larvae keep appearing, it is possible that some decaying matter is further down the toilet drain, and to remove this, the reader should use a longer toilet brush (or a so-called “plumber’s snake”) to clean the drain.

This should fix the reader’s problem of the “worms” that are in his toilet. No one likes to find worms or other creatures in their house, but we suppose the toilet is a better place to find a worm (or larva or whatever the case may be) than most areas of the house.