Worm in Toilet Bowl Probably Drain Fly Larva

One of our readers found a black worm-like-organism in her toilet bowl after urinating. Like any bug-fearing human, her initial thought was that she must be dying from an internal worm infestation. However, after calming down and doing more research she thinks it might be a drain fly larva, not some deathly parasite. She described the specimen as: black, 1/2 inch long, segmented-ish, with a small head, and maybe a tiny split at the tail. She says is swam/crawled up the toilet bowl. What kind of creature is this?

We agree with our reader, we think the creature might be a drain fly larva. Drain fly larvae are commonly found in toilets, and they roughly match the appearance of the specimen in the photograph. While drain fly larvae aren’t segmented, they can appear that way. Here is an example of a drain fly larva photographed under a microscope from another reader:

ATTENTION: GET PARASITE HELP NOW! At All About Worms we get a lot of questions about skin parasites, blood parasites, and intestinal parasites in humans. Because we can't diagnose you, we have put together this list of doctors and labs who understand and specialize in dealing with parasites in humans! That resource is HERE

drain fly larva

As you can see, the texture and pattern of the body makes it look “segmented-ish.”

We are hesitant to confirm that she definitely found a drain fly larva for two reasons: the color and the size. First, drain fly larvae are often translucent with a black head. The specimen our reader found is very dark black, or at least appears that way in the photo. Of course, not all drain fly larvae look the same, and it is totally possible that this one is simply darker. Second, drain fly larvae are typically really small. At their largest, they are 10 mm long, which is only about .4 inches. However, the average size is about half of that, around .2 inches. So, either our reader found an especially large drain fly larvae, which is possible, or the creature isn’t a drain fly larva.

No Paywall Here!
All About Worms is and always has been a free resource. We don't hide our articles behind a paywall, or make you give us your email address, or restrict the number of articles you can read in a month if you don't give us money. That said, it does cost us money to pay our research authors, and to run and maintain the site, so if something you read here was helpful or useful, won't you consider donating something to help keep All About Worms free?
Click for amount options
Other Amount:

If this is a drain fly larva, our reader just needs to clean out her toilet. Drain fly larvae feed on the organic matter lines the pipes leading up to a toilet bowl. So physically removing the grime with a brush and cleaning gel will get rid of any other drain fly larvae feeding in her toilet. If the creature isn’t a drain fly larva, cleaning the toilet can’t hurt. As long as she doesn’t continue to find these creatures in her toilet, or in other places around her home, she shouldn’t stress about the situation.

In conclusion, one of our readers found a specimen in her toilet bowl. We aren’t 100% convinced that it is a drain fly larva, but we think it is a good match!


Article Name
Worm in Toilet Bowl Probably Drain Fly Larva
One of our readers found a specimen in her toilet bowl. We aren't 100% convinced that it is a drain fly larva, but we think it is a good match!

Author: Worm Researcher Dori

Leave a Reply

Your email address will not be published. Required fields are marked *