A woman wrote to us about getting infested with horsehair worms while visiting Costa Rica, and wanted advice on how to permanently rid herself of them.

We recently received a question through the All About Worms Facebook page about “two red worms in the toilet bowl.” The worms were “10 cm long, thin, like one millimeter in diameter, and alive, even in the water, they were still moving.” The reader didn’t actually ask for an identification, but instead asked if the worms might be parasites. This is his main concern, and we will focus on this question, although the answer is of course tied to what exactly the reader found, so we’ll touch on the matter of identification as well. What might the red worm in the toilet be, and are they parasitic?

A reader wrote to us a few days ago about a “long thin brownish worm” that is four to five inches (10-13 centimeters) long and was found under a potted plant. The potted plant was sitting on top of a tree stump, although this probably isn’t of relevance as far as identification is concerned. The reader said the worm appears to have “tiny scales and slithers rather quickly like a snake.” The reader is wondering what the worm is and what to do with it, and he also wanted to know if he found a pest.

A couple of days ago we received a question from a reader in Northern California who found a six-inch “worm-like being with black horizontal stripes and a flat, fan-shaped head.” By “fan-shaped head,” we are assuming our reader means the worm’s head is, first, clearly distinct from the rest of its long, striped body and, two, somewhat flat and spread out, perhaps in half-circle shape. If this is true, we have a pretty good idea what our reader found: a hammerhead worm (sometimes spelled “hammer head worm”).

In a fairly long email composed of short, descriptive sentences that were each on their own line, which made the message look like a poem, we were asked about the long, skinny, brown worms that come out after it rains. The reader noted several things about the worms, most notably that they are, once more, long, skinny, and brown, and also that the worms dry out on the sidewalk after the rain evaporates. So, we have a basic “what are the worms that come out after its rain” sort of question, which we have addressed in different contexts a couple of times before. The answer to the reader’s precise question is extremely simple – the long, skinny, brown worms are almost certainly just earthworms – but her email suggests other dimensions of interest, so we’ll discuss why earthworms come out after it rains, and why they often end up dead on the sidewalk when the precipitation and its aftermath have passed.

With large font and an enormous amount of consecutive question marks, a reader wrote to us to ask about a black worm in her bathroom. The worm is about seven centimeters (slightly less than three inches) in length, which is relatively long for a bathroom pest. (Larvae, the most common creature to find in a bathroom in our experience, are generally several times shorter.) The reader says the worm has no “texture” on its body, by which she means it has smooth skin, and the worm evidently has a titanic tolerance for Raid and other insecticides, as it didn’t die after being continually sprayed for 10 to 15 minutes. The reader is wondering, one, what the long black worm is (if it even is a worm) and, two, where it came from.

A concerned reader wrote to us recently about a long, black worm he found in his house. He is worried that his dog has “a terrible worm of some kind.” We are of course highly sensitive to his concerns, but the reader makes no explicit connection between his dog and the long, black worm he found. He merely mentions that he came home (and presumably found the worm) and is worried about his dog. He didn’t mention any behavior of the dog that implies it has a worm infection, nor did he say he saw the worm come from the dog’s body. We are therefore slightly puzzled why he immediately linked the worm he found to his dog. In any case, he only asked us to identify the long, black worm, so hopefully in helping with this we can provide some guidance.

A reader wrote to us a while ago about a long worm he found in the garden of his rural home in France. The reader found the worm “wriggling through the long grass” and estimated it to be about as long as wholemeal spaghetti (or presumably any type of spaghetti, for that matter). The reader was wondering what this very long worm might be, and our best hypothesis is that it is a horsehair worm (Nematomorpha), which are also known as Gordian worms (after the legend of the Gordian knot). Although a long worm that resembles spaghetti is very likely to be a horsehair worm, it is worth mentioning that it could be something even more common: a simple earthworm.