Insects have six legs, right?

Nature Talk
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So where are legs 5 and 6 in Polygonia c-album? :-)
https://www.inaturalist.org/observations/127940521
I looked at quite a lot of pictures of this butterfly lately, and I keep seeing four legs.

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2

Itā€™s probably holding the front two up.

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A whole group of butterflies are called the brush-footed butterflies because the two front legs are modified into short brushes for cleaning the head. They have only four legs that look like legs.

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There are some species of butterflies which are standing on four legs. The caterpillars will have all 6 legs. Those prolegs behind not counted. When the caterpillars become butterflies, the front legs become attached very close to the body, almost vestigial, I guess there is a use of those front legs. I just did not observe them close enough.

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Brush-footed butterflies: https://www.inaturalist.org/taxa/47922-Nymphalidae

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It"s explained here: https://en.m.wikipedia.org/wiki/Nymphalidae

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Have you ever seen a butterfly using those two modified front legs? I feel like Iā€™ve seen it before but not quite sure and I want to see what it looks like when theyā€™re cleaning their little heads :grin: maybe send a video

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You know, it seems to me that I have seen it, too, but I canā€™t bring up a specific memory. Maybe I just thought it.

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There are some good pictures of those reduced front legs in this research article: https://www.researchgate.net/figure/Reduced-first-thoracic-limbs-of-Bicyclus-anynana-Nymphalidae-Indicated-by-the-black_fig1_51595675

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Different species, but hereā€™s a good photograph showing them as well:

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The family Nymphalidae are characterized by their reduced front pair of legs, making it look like they only have four. Note also some males in Riodinidae and/or Lycaenidae will also have a reduced front pair of legs too.

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Donā€™t know about common name, but Nymphalids hold first pair of legs tight to the body, they can be seen though.

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Zooming out on your question a little bit, insects have 6 (i.e. 3 pairs of) locomotory appendages, known in simple terms as ā€˜walking legsā€™; there are several additional non-locomotory appendages, such as those used as mouthparts in beetles for instance. In a typical insect, all 6 of the former will be used for locomotion, but thenā€¦ there are hardly any taxa of life where the ā€˜typicalā€™ form is without exception. So in the case above, as in many other insects, certain walking legs are modified to perform special functions, so they do not appear to be typical ā€˜legsā€™ - but they are present.

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Strictly speaking, insects have six legs when they are fully intact. Some arenā€™t very good at keeping them attached to their bodies.

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Some tetrapods have four limbs but only two legs (e.g. birds, humans), and some hexapods have six limbs but only four legs (e.g. mantises, brush-footed butterflies).

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If weā€™re going to call those nymphalid appendages ā€œreduced legsā€ then logically, we should refer to our arms and legs as ā€œmodified fins.ā€

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A good example of this is when insects get their legs stuck in Milkweeds (Asclepias). Hereā€™s a good video showing this with a bee leg (9:30 - 9:48, also warning language) from Crime Pays but Botany Doesnā€™t.

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Oh my, thank you all so very much! I am pleased I asked that silly question because your replies have been quite enlightening! I had been reading up on that particular species of butterfly to find out about that ā€˜missing pair of legsā€™, but it had never occurred to me to check the entire FAMILY. Duh!

Today I noticed that Minois dryas also seems to have four legs only, and now that I have read all of your replies it makes sense, of course ā€“ itā€™s the same family!

Thanks again for pointing me to the solution. I didnā€™t see the wood for the trees.

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There many species that have six legs but not more than 4 legs insects.

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This may not be news to you, but it was for me: at least one species of the ā€œ4-leggedā€ Nymphalidae uses their middle legs to fight.

While doing the usual round yesterday I noticed two butterflies doing their dance flying around one another near some brambles. I assumed it was a male and a female.

Then they came closer to where I was and landed on a plant near me, which obviously was an invite to take pictures that I couldnā€™t resist. Thatā€™s when I realized that the two were not in a particularly loving mood, quite the opposite, they seemed to be disagreeing about something.

https://www.inaturalist.org/observations/132116351

https://www.dropbox.com/s/ptox038bg8iyc3b/Coenonympha_arcania_arguing_anigif.gif?dl=0

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