From Oxford:


any small creature with six legs and a body divided into three parts. Insects usually also have wings. Ants, bees and flies are all insects

Insect is often used to refer to other small creatures, for example spiders, although this is not correct scientific language.


  1. a long thin creature with no bones or legs, that lives in soil

  2. long thin creatures that live inside the bodies of humans or animals and can cause illness

  3. the young form of an insect when it looks like a short worm

I find both these definitions oddly restrictive. Insects have 6 legs and worms (in the primary sense) have none. The other senses of worm are also specific. There are many small creatures who do not fall into these categories. Centipedes definity have legs, and a lot more than six. Is there a common (not too scientific) word to refer to all small creatures?

A bug doesn't work, as is defined as

chiefly North American A small insect:

a thick green scum which crawls with bugs, centipedes, and worse

Insect, not creature, not worm. Also note the exclusion of centipedes from the umbrella of bugs. In fact, Oxford defines centipedes exclusively in scientific terms.

A predatory myriapod invertebrate with a flattened elongated body composed of many segments. Most segments bear a single pair of legs, the front pair being modified as poison fangs.

Although Oxford here lists an informal sense of insect:

informal Any small invertebrate animal such as a spider or tick.

It curiously drops this definition in the advanced learners' version. Moreover, it's reluctant to use the term in its own definition of spider:

An eight-legged predatory arachnid with an unsegmented body consisting of a fused head and thorax and a rounded abdomen. Spiders have fangs which inject poison into their prey, and most kinds spin webs in which to capture insects.


  • Is there any word, preferably not too informal, which would include all small creatures like insects, worms, spiders and centipedes; without having to resort to biological jargon?

  • Also, how right/wrong is it to use insect or bug for this purpose?

  • 10
    For all those critters except worms, the word is arthropods. Worms, however are not arthropods. You can choose to ignore biology, but worms are simply very, very different. You could go for critters, which would prolly include all you mentioned. Insect is plain wrong, spiders and worms are not insects. As for bug, it excludes worms as well according to Wikipedia.
    – oerkelens
    Jun 3, 2015 at 19:38
  • 15
    I don't know if you'd consider invertebrates to be "biological jargon", but it would work for me - either ignore bigger ones like octopuses and giant squid, or go for small invertebrates. Jun 3, 2015 at 19:49
  • 7
    I find ODO's restriction of bug to insects to be overly restrictive. My understanding of it is closer to AHD: b. An insect of any kind, such as a cockroach or a ladybug. c. A small invertebrate with many legs, such as a spider or a centipede.. I don't consider worms to be bugs, but perhaps they fall under MW's definition: an insect or other creeping or crawling invertebrate (as a spider or centipede)
    – choster
    Jun 3, 2015 at 20:39
  • 1
    @choster: Thanks for the AHD link. That's the best and most comprehensive entry, I think.
    – Tushar Raj
    Jun 3, 2015 at 20:42
  • 2
    I expect questions on etymology on this site; I'm amused by the question on entomology!
    – Ray
    Jun 5, 2015 at 15:49

10 Answers 10


Small children are easily interested in small creatures and, unsurprisingly, primary schools in Britain find the study of such animals a good starting point for much of the curriculum. However, it is was thought that calling them "creepy-crawlies" would risk alienating pupils and trigger the fear and distaste which was common in their grandparents' day.

So the term for these small creatures most often used in British Primary Education is minibeasts For a general view of UK minibeast history see this wikipedia article.

"Minibeast" or "Minibeasts" is a term for a variety of arthropods and other invertebrates, including spiders, ants, butterflies, bees, wasps, flies, woodlice 1, and many others.

  • Related link: english.stackexchange.com/questions/166006/origin-of-minibeasts
    – user66974
    Jun 3, 2015 at 20:06
  • @TusharRaj I added a link to your wiktionary page, but, re-reading it find the definition to be essentially limited to "insects and bugs", with "etc" leaving the rest to the imagination.
    – Margana
    Jun 3, 2015 at 20:27
  • 2
    Being from the U.S. I haven't heard this, but I do like it. Unfortunately, without having the actual definition there I might think small animals were included as well depending on the context it was used in. (like mice, squirrels, etc) Jun 3, 2015 at 21:09
  • 2
    @TusharRaj I'm aware of that, since the definition is right there. I was saying as somebody who hasn't heard the term before, The term is clear enough that I have an idea of what it is, but I wouldn't go to Wikipedia to see the exact definition if I came across it in text, so the wrong meaning may get across to me if its really so important for the OP to distinguish between these. Since it says its mostly a British term, that might be more or less of a risk depending on the audience. Jun 4, 2015 at 14:49
  • 1
    I disagree with the promulgation of this term. Not only does the term suggest a superset of "creepy-crawlies," but I think it teaches the wrong lesson. The fact is that our revulsion toward these creatures is adaptive, not arbitrary -- many carry disease; they count many parasites among their numbers; they generally indicate decay. The point should be that we need to cultivate curiosity in spite of revulsion. The dissection of cadavers is a good example. The cadaver taboo held back our understanding of anatomy for centuries. Jun 6, 2015 at 22:25


A spider, worm, or other small flightless creature, especially when considered unpleasant or frightening:

^ Covers all three cases.

Also, despite your dictionary defining "bug" as an insect specifically, i wouldn't balk at using it to describe worms or spiders as well.

  • 6
    +1 for your footnote especially. Also critter (especially in the Southern U.S.).
    – Dan Bron
    Jun 3, 2015 at 19:43
  • 5
    I happen to agree with that definition of "critter". There's a reason i didn't include it in my answer. @TusharRaj
    – Scimonster
    Jun 3, 2015 at 20:00
  • 9
    Entomology be damned, I can't see how one can conceive of the demotic use of "bug" as excluding spiders and centipedes. Worms, no.
    – David Pugh
    Jun 3, 2015 at 20:01
  • 7
    I agree with @David, "bug" covers insects, spiders and centipedes, but not worms (unless the "worm" is really an insect, for instance an inchworm). I've only ever heard critter as a synonym for "creature" and generally meaning a small to mid-sized animal (mammal, reptile or amphibian). Jun 3, 2015 at 21:14
  • 4
    I think of "critter" as any smallish animal - rats, yes, rabbits, yes, lizards, yes, dogs and cats, no. Also, large lizards like say komodo dragons, also no.
    – neminem
    Jun 3, 2015 at 22:02

Bug is certainly what I would use, and what I would expect those around me to use. And I am American, so I think Oxford is simply wrong about how we use the word. Merriam-Webster, for instance, gives the principal definition of bug as

1 a : an insect or other creeping or crawling invertebrate (as a spider or centipede)

This matches your desired usage perfectly. Note the near-reference to Scimonster’s suggestion of creepy-crawlies – Merriam-Webster here makes it pretty clear that bug is used as a more-formal creepy-crawly.

That said, if we are being truly formal (read: technical), the third definition is the “formal” one:

1 c : any of an order (Hemiptera and especially its suborder Heteroptera) of insects that have sucking mouthparts, forewings thickened at the base, and incomplete metamorphosis and are often economic pests —called also true bug

This fact is, however, outside entomology, not widely known, and would be regarded by most as trivia. By comparison, the specifics of insect are much more widely known, though I’d guess the majority of speakers are unlikely to care very much in practice – just because someone knows, or at least at one point learned, that insects have three body parts, six legs, etc., doesn’t mean they care to use the word so exactly. But many more know/care about insect’s specific definition than do about bug, as indicated by the fact that some entomologists have resorted to the phrase true bug for Heteroptera. Thus bug is very much my recommendation.

  • 5
    I would never refer to a worm as a bug. That seems to be a pretty significant part of the asker's requirements.
    – talrnu
    Jun 4, 2015 at 14:31
  • 10
    @talrnu I certainly would, and the definition given by M-W would definitely include them, since they are invertebrates that both creep and crawl.
    – KRyan
    Jun 4, 2015 at 14:32
  • 2
    @talrnu You already said as much, and I already said I disagree. I am not going to change my answer to match your opinion, because I disagree with you. I address the OED's inaccurate statements about how the word is used in North America in my answer. I do not feel that their error deserves more mention than I have already given it. If you wish to do the research to actually back up your statements, and make them more than mere opinion, I suggest you do so and make it an answer, if your research actually does back you up. Either way, continued commenting is inappropriate.
    – KRyan
    Jun 4, 2015 at 18:11
  • 6
    I have to agree with @KRyan: in North American usage, bug is very close and less informal than creepy-crawly (which is even closer). Since "bugs and worms" is also common, there is somewhat of a distinction between them, but most people would not quibble -- after all, worms "bug" a lot of people as well.
    – shipr
    Jun 4, 2015 at 19:14
  • 2
    Seems like part of the conflict between KRyan and tarlnu here could be attributed to regional differences in usage, which can be surprisingly wide in AmE. I would never call an earthworm a "bug" and I would do a double-take if I heard anyone else do so, but then I have lived in the Pacific Northwest almost all my life. I'm certainly open to the idea that that usage may be perfectly ordinary elsewhere in the country. The OED isn't much help validating US dialects and regionalisms, as others have pointed out, since it tends to lump all of AmE together. Jun 5, 2015 at 4:44

If you're looking for a negative sense, you might use "vermin" -- small, swarming, repulsive, potentially-disease-bearing creatures.

It's a very unscientific term, including rats, frogs, toads, centipedes, and millipedes, as well as insects and most types of worms (except earthworms and redworms, which are good for the soil). Depending on your sensibilities, it might also include mice, spiders, ants, and termites; it might even encompass scorpions and lizards, and maybe even lobsters.

  • 1
    @Tushar Raj: Thanks! But you're right, it's a pretty broad term, not something to use when you want precision. I think it dates back to the Middle Ages, which classified animals by habits and habitat much more than by biology. ("Fish" included turtles and whales, for example.)
    – ExOttoyuhr
    Jun 3, 2015 at 19:57
  • 3
    This was my first instinct upon reading the question too, though it doesn't fit perfectly. I think for clarity, it would be acceptable to say "worms, bugs and other vermin", for instance, or something similar. On the other hand, simply saying vermin by itself, as in "an abandoned house infested with vermin", would generally imply rats or other vertebrates as well.
    – recognizer
    Jun 3, 2015 at 20:54

preferably not too informal

This is the most formal one: they are all invertebrates.

Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. This includes all animals apart from the subphylum Vertebrata. Familiar examples of invertebrates include insects, crabs, lobsters and their kin, snails, clams, octopuses and their kin, starfish, sea-urchins and their kin, and worms.

But the usage depends on the context.

If your text is somehow related to science, don't call spider an "insect". Spiders & insects are "arthropods" (not "arthropodes"), together with worms they are "invertebrates".

  • I believe, in English, it is "arthropod" and "arthropods" (no e after the d). From Saunders Comprehensive Veterinary Dictionary: arthropod -- an individual of the phylum Arthropoda.
    – JLG
    Jun 4, 2015 at 13:50
  • 1
    @JLG yes, you are right. I'll edit my answer. Jun 4, 2015 at 13:54
  • The problem with "invertebrate" is that it's far too broad, as your passage makes clear. Jun 6, 2015 at 22:15
  • @JasonMelançon it could be specified with adjectives, like "small invertebrates", "land invertebrates". But I avoided offering variants, as I do not have the proper feeling of language and cannot say if one is good or bad. Not a native speaker, alas. Jun 6, 2015 at 22:18
  • @JasonMelançon also, there's little information on the context. The accepted answer is "minibeasts". As I feel, it is only appropriate for a fairy-tale or some cartoon. But the OP found it acceptable for their context. Jun 6, 2015 at 22:22

"Vermin" or "pests" can be any small creature, usually with a negative connotation, but including things as large as rats or even opossums. "Creepy-crawlies" is good but very informal. But as for "bug" -- scientifically, only a small subset of insects are bugs. But the word has expanded, and can now also mean an infection, or a computer glitch. I would argue that as long as the context doesn't imply you mean only insects, "bug" isn't actually wrong in informal English.

(Scientifically, both worms and insects are invertebrates -- creatures without an internal spine -- which then includes spiders and even coral.)

  • 1
    "scientifically, only a small subset of insects are bugs. But the word has expanded" -- well, the scientists contracted the meaning for scientific purposes by using an existing English word with a new jargon meaning. Civilians ignored this contraction, and also expanded it further with new meanings. Jun 4, 2015 at 9:00
  • c.f: "mathematically, a group is a monoid with inverses. But the word has expanded. I would argue that calling the Beatles a group, or a "pop group", isn't actually wrong in informal English" ;-) Jun 4, 2015 at 9:05
  • Steve: perhaps. My biology friends insist that it originally meant a subset of insects and has diverged; etymonline.com/index.php?term=bug seems to disagree. The argument still stands, though.
    – Vynce
    Jun 4, 2015 at 22:27

Minibeast - this term is commonly used (at least in the UK) by charities and other groups which involve children in outdoor activities learning about nature. See also Cbeebies Minibeasts with Jess

The UK organisation Buglife works to protect ALL invertebrates regardless of size or number of legs, and uses the term bug to encompass all of these.

Invertebrates are animals without backbones and make up the great majority of animal life, with 40,000 species in Britain alone and many millions on Earth.


I would say that in the Swedish language the word "kryp" have this meaning. Small creatures that is not built like us mammals, birds and fish. Non vegetable things that move around, but do not have a skeleton. (Or we just can't tell.)

A direct translation to English would be "crawl". But "crawlers" would perhaps correspond more closely to how it is perceived. Yes, it comes from the verb crawl, even if many of them can jump, fly and swim. But it is usually when they crawl on our bodies we notice them.

The word often have a negative association to it, but not necessary.

  • 2
    But it is usually when they crawl on our bodies we notice them You sold me. +1 for the information, even though the term is probably unusable in English.
    – Tushar Raj
    Jun 5, 2015 at 13:09

In french, it is common to see products to kill calling them "indésirables" or "nuisibles".

You can translate to get :

undesirable, unwanted, unwelcome, pest

  • "Undesirable" could be interpreted as referring to people.
    – Kevin
    Jun 4, 2015 at 14:35
  • @Kevin You are totally right, but since I don't know where this word will be used, context can be leading to insect like reference... or not.
    – Yohann V.
    Jun 4, 2015 at 14:39

Wug is a portmanteau of worm and bug. It's not very common though, and might need to be explained.

A Google search for wug worm bug reveals hundreds of results, many from books on taxonomy. I couldn't just search for wug because it has other meanings as well.

This is either very informal or very formal -- i can't quite tell. :P

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