Black Worms in the Toilet

A reader has been finding black worms in his toilet over the last couple of months. The worms in the toilet (we should actually say worm in the toilet, as only one is ever found at a time) appear seemingly out of nowhere, and they do not appear to be linked to anybody using the toilet. (In other words, the worms aren’t coming from somebody, which is good.) What are these black worms in the toilet? Is our reader finding a type of worm at all, or might he be finding some kind of larva (or larvae, since he’s found five)?

Before submitting his question, the reader did a decent amount of research, which we appreciate. The reader looked into moth fly larvae (also called “drain fly larvae”), but concluded that he likely didn’t find this type of larvae because they are smaller than whatever he’s finding in his toilet. The creatures in our reader’s toilet are about 3/4 of an inch to an inch long, and moth fly larvae are less than half this size, tending to be around a quarter of an inch long. On a number of occasions, we’ve written about moth fly larvae. In fact, we wrote about moth fly larvae recently, and in the context of finding them in the toilet interestingly enough. Although moth fly larvae are found in toilet bowls with some regularity, we agree that our reader probably didn’t find this type of larvae, not only for reasons related to their size, but also because the creature our reader found doesn’t look like moth fly larvae. (If you click on the link above, you will find a fairly clear picture of a moth fly larva that a reader submitted.)


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Speaking of the appearance of our reader’s find, he sent us two nice pictures:

Black worm in Toilet

Black worm in Toilet 2

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Based on the creature’s appearance, the reader speculated that he might have found black soldier fly larvae, and we think this is as good a guess as any (because when we saw the pictures this is immediately what came to mind). Black soldier fly larvae – which commonly go by their acronym, BSFL, and not so commonly by their scientific name, Hermetia illucens – are creatures that, like moth fly larvae, we have written about several times before. They most frequently come up in connection with certain kinds of composting operations, for which they are often used. So, when people find BSFL, they almost always find them in a compost heap (or a naturally occurring counterpart, like a pile of decomposing organic matter in the forest). For this reason, it is fairly bizarre that our reader is finding BSFL in his toilet (if indeed he is), but it’s not unthinkable, as they can sometimes be found in toilets that haven’t been cleaned in awhile, where waste has accumulated. Obviously, we have no idea what shape our reader’s toilet is in, but he did mention it was downstairs, so perhaps it escapes regular cleanings. If the toilet is in need of cleaning, then it ought to be cleaned to get rid of the BSFL, which our reader expressed interest in doing.

Unfortunately, we can’t be sure the black worms in the toilet our reader found are black soldier fly larvae. They normally aren’t in toilets, unlike moth fly larvae and other similar creatures, such as black scavenger fly larvae, which is another type of creature we considered in the course of writing this article, but they don’t really look like our reader’s find. On the other hand, the pictures we were sent really look like black soldier fly larvae, so that is our best guess, and we would suggest that our reader looks into them (he can start on this site) if he cares to know more about them.

10 thoughts on “Black Worms in the Toilet

  1. At the end of the article it says they appear to be a black soldier fly larvae. it also said to reference this on this site for how to get rid of. hope this helps.

  2. I found one in my bathtub the other day, and then another one this morning in my closet on a shirt!! I almost died!! It looks just like the top picture. Black and wormy, with some fur on bottom maybe it’s the legs?! What is this and why are they in my apartment?! Do I need to do something to get rid of them?

  3. I found one today in my toilet bowl – gross!!! Put Harpic toilet cleaner, didn’t work. Tried Mould Killer, didn’t work!! Put salt on it. Finally stopped crawling. Came home from work, it had crawled from where I had left it, and is dead! So I think salt is the way to go!! Good luck!

  4. I have these exact bugs coming up in my tiolet. I have seen up to 5 on the floor and 2 in the toilet all at once. Shortly after cleaning. I live in a motor home and feel it is a issue with the R.V. park. It is very gross and I have to check the toilet even in the middle of the night before use. What can a get to eliminate these discusting bugs

  5. I have these exact bugs coming up in my tiolet. I have seen up to 5 on the floor and 2 in the toilet all at once. Shortly after cleaning. I live in a motor home and feel it is a issue with the R.V. park. It is very gross and I have to check the toilet even in the middle of the night before use. What can a get to eliminate these discusting bugs

  6. We are trying to get rid of these wormy things in our toilet & sewer pipes. We live in our RV and they keep coming back even when we think we’ve gotten rid of them.

  7. Did anyone find anything more about these? I found the exact same thing this morning. we keep our house very clean and have no idea where this would have came from!

    Look forward to leaning more and how this got in there!

  8. Did anyone find out exactly what this is? I found one of these today and we keep the house and bathroom very very clean. Anyone have any thoughts?

  9. I also have this larvae in one toilet, sometimes up to 20! I have also seen the mature fly. How do I get rid of them?

  10. I am very interested in this because I have found two of this exact same thing now on two different times! only one in the toilet at the time! I clean mine pretty regularly and just did yesterday and found one tonight! We live in the country and have a septic system. Could it be something in the septic system and one finds it’s way up from there? I have a total of 3 bathrooms. One upstairs and two downstairs. I have only found the culprit in one of the downstairs bathrooms only! Please help me find out what they are and how to get rid of them! I hate bugs and worms and such and do not wish to have them in my house!!!!!!!! The ones I two that have appeared thus far look exactly like this fellows!

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