How did it come to be that so many types of creatures typically known as worms are actually insect larvae? Silkworms are not actually worms at all, but larvae of a type of moth. Another example being the Maguey worm, which is supposedly the worm in some types of tequila and also not a worm, actually also a type of moth-larvae?

I find it curious that Wikipedia would have a creature with the word worm in its title, and then the first thing they tell you about it is that it is actually an insect. These are just the two examples I came across, there are probably more.

  • $\begingroup$ I’m voting to close this question because it is a language usage question rather than one about a biological concept or mechanism. $\endgroup$
    – tyersome
    Mar 16, 2021 at 4:42
  • $\begingroup$ Discussion on meta: biology.meta.stackexchange.com/q/4178/52598 $\endgroup$
    – jakebeal
    Mar 17, 2021 at 10:56

4 Answers 4


Excellent question. My zoology professor during biology undergrads explained this by clarifying that "worm" is a term that relates to one type of shape of animals. As such it does not carry any additional information on the relatedness of animals or their developmental stage.

This view also seems to align with wikipedia.

  • $\begingroup$ but worms are not insects though, worms have no exoskeleton, breathe trough there skin and dont molt. They are both Invertebrates though. I'm trying to get my head around this. $\endgroup$
    – Neil Meyer
    Feb 11, 2021 at 21:55
  • 4
    $\begingroup$ "worm" is not a word with an exact scientific meaning (like the word insect). It's use colloquially to name any animal that have an elongated cylindrical shape. (Maybe snakes escape from this use today, but not in the 13th century, as you can read in en.wikipedia.org/wiki/Worm) $\endgroup$
    – heracho
    Feb 11, 2021 at 22:10
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    $\begingroup$ @NeilMeyer It's not too unusual for colloquial terms to not match the scientific counterparts. In some cases the colloquial terms have shifted with science, in other cases not. For example, "fish" once referred to all sorts of non-(biological fish) animals that lived in water, including marine mammals. We still see it used this way in jellyfish, starfish, the more generic "shellfish", etc. $\endgroup$
    – Bryan Krause
    Feb 11, 2021 at 22:45
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    $\begingroup$ @Bryan Krause: And then there's the silverfish, which doesn't live in water. en.wikipedia.org/wiki/Silverfish $\endgroup$
    – jamesqf
    Feb 12, 2021 at 1:21

An addition to tsttst answer:

"Worm" can go to very abstract realms, in Neuroethology "Worm" can be a stimulus attribute:

horizontal movement implied:

▄▄▄▄▄▄ would be considered "Worm configuration"

▀ would be considered "antiworm" (ignore the white stripes)

at this level of abstraction underlying taxa would not matter at all, could be an eel, a snake or a branch , or a piece of cardboard. As long as it triggers the "worm " synapse


This isn't really a matter of biology so much as etymology.

The English word for "worm" was applied to any sort of slithering distasteful creature for centuries before we actually started get our taxonomies properly sorted out. Thus, the word "worm" ended up in the common names for lots of organisms without any real relationship to one another besides their generally cylindrical shape. It's also unsurprising that there are so many different things that have ended up with that shape, because it's a really simple one to grow and thus an easy case for convergent evolution.

In short: "worm" just describes a common shape and isn't really a biological term of art.


In common English, worm is not a precise biological term, and long predates even the idea of precise biological names. It's a generic descriptor for creatures that are long & skinny, without much in the way of legs. So we have earthworms, silkworms, tapeworms, &c. Even dragons can be called worms - or wurms, wyrms, &c, depending on your spelling preferences. For instance, Old English epic Beowulf https://en.wikipedia.org/wiki/Beowulf ends with Beowulf fighting & being slain by a wyrm or dragon.

PS: Worm is also applied to non-biological things, for instance the worm gear: https://en.wikipedia.org/wiki/Worm_drive


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