Wing-roll behaviour of some members of the Lycaenidae family

[IacobnDG]

Something which no-one here seems to have mentioned is that male Common Blues (in NI at least) do this very distinctively as they open their wings to bask. This is the only time I have seen the behaviour although I'll have to look out for it more having read this thread. It has always confused me why they do this as they look like they are 'unfolding' their wings before basking like the picture below.

[ernie f]

Jake, thanks for that. It certainly is an odd behaviour. I am fascinated by it.

[ernie f]

A Purple Hairstreak doing a wing roll at Binswood on 11th July 2020 at around 8am in full sunshine. Not something they seem to do much, but they do it sometimes.

This one did it for about 20-30 seconds. There did not seem to be anything else to disturb it nearby (except me of course), but I was a fair way away when I first saw it rolling (these shots are taken on full zoom and then cropped too). It only stopped as I got closer to it. I actually saw it brace itself as it realized I was there and then when it thought I was too menacing, it flew off.

[Wurzel]

Here is a Green Hairstreak wing rolling at Martin Down, Hampshire.

Have a goodun and stay safe

Wurzel

[ernie f]

9th June 2021 at Magdalen Hill

I have seen Small Blues wing-roll before but this one had a bent hind wing and kept all its wings ajar as it did it, which made it look all the stranger...

[ernie f]

SSB female - Broxhead on 25th June 2021
1st female of year seen at this location and it was wing-rolling.

[ernie f]

It's been a year since I posted on this but I think it's an observation worthwhile recording here.

Today I visited Broxhead for the Silver-studded Blues and found a pair of which the male only was wing-rolling. As he was doing it the female hardly budged.

I believe he may have been agitated by the proximity of a small green grasshopper which just so happened to be sitting beside them. When he rolled his wings, the grasshopper moved but did not go away. Unfortunately I couldn't get the grasshopper in shot AND get a good picture of the wing-roll at the same time.

[PhilM]

Hi Ernie,

The more I learn about this behaviour the more inclined I am to believe Lycaenidae wing rolling is a predator deception mechanism. It could be that some individuals see potential threats in different ways which might explain why some express clear, energetic wing rolling and others don't seem to be bothered at all, even when faced with the same threat. This theory could also explain why your male didn't wing roll merely because you were in his vicinity but did when he saw the grasshopper - and the female didn't bother at all. You could make a comparison to how we humans might react when under threat - some would shout out or flee, others would remain passive, depending on previous experiences of the threat and on individual personality. Perhaps the butterflies are doing the same thing, in their own way they are expressing their individual personality when faced with what some perceive as a threat and others don't?

[Matsukaze]

We can add Chequered Blue to the list:

https://youtu.be/gOXMGpHc7ww

[Matsukaze]

Large Blue at Collard Hill today:

https://youtu.be/Fyuja0Hbb70

[ernie f]

Matsukaze

Thanks for those vids. I am always keen to get as many examples as I can of this behavior and these are VERY fine examples!

Phil

I am always drawn to enigmas and love to try and puzzle them out. Not only butterfly behaviors but just about anything that is a mystery. And this one certainly is enigmatic.

It's possible that in this case the female didn't even see the grasshopper - she was facing away from it.

I have an example from the past where a Small Blue was wing-rolling. I thought it was my proximity that caused it until I saw a very VERY small fly sitting next to the butterfly. I only saw it when it flew off. The fly was clearly no threat to the butterfly BUT I like your predator deception reasoning anyway. My thinking is that it doesn't have to always be triggered by the proximity of a real predator as such BUT the mechanism it uses for predators is automatic - in other words instinct makes it happen whenever the butterfly is in similar situations such as merely being agitated in some way. Even if its not a predator nearby perhaps its always best for the butterfly to err on the side of caution. There are so many species that masquerade as predators for self preservation. Maybe the butterfly has just evolved to do it in all eventualities, just in case!

I am starting to gather that pretty much every time I see a wing-roll it is rarely anything to do with me - rather to things near said butterfly that IT is aware of but I am not, usually because it is so small or I am just not being observant enough!

Regarding your view that different butterflies of the same species react differently to the same stimulus must be true I think. It is as you point out certainly true for humans, but it is also true for higher mammals in general. Some people may think it would not be the case for insects because their brains don't work the same as mammals BUT I once saw a show on TV that amazed me when it showed a particular species of bug where two males had completely different strategies for winning a female!

Thanks for your input by the way. Every little bit of info and opinion helps.

[PhilM]

it doesn't have to always be triggered by the proximity of a real predator as such BUT the mechanism it uses for predators is automatic - in other words instinct makes it happen whenever the butterfly is in similar situations such as merely being agitated in some way. Even if its not a predator nearby perhaps its always best for the butterfly to err on the side of caution.

And the reasons for the wing rolling behaviour could possibly go even deeper than that Ernie. Current scientific thinking in some quarters is that an adult moth or butterfly can remember events that happened to it when it was a caterpillar. To take your recent observations regarding the grasshopper incident, just suppose for a moment that when the said butterfly was a caterpillar a grasshopper happened to jump on or near him, not to predate the caterpillar but just by accident. Now, as the butterfly remembers that he had once been startled by a grasshopper while he was innocently chomping away on some leaf or another as a larva, the memory could set off a trigger to roll his wings in order to deceive the grasshopper. So he has 'learnt' to roll his wings in times of stress, but the trigger is individual to him. This is just a theory of course, not based in proven fact - yet- but it could be true.

I remember when I was much younger a teacher at school avidly taught us kids that animals do not have emotions and cannot cry, for example. He was trying to explain the difference between 'superior' homo sapiens and the rest of the animal kingdom. Some years later I moved into a flat. My neighbour had a domestic cat (feline not lepidopteran ) which managed to escape through an open window onto the roof, several stories high. The RSPCA and fire brigade where unable to help, we were at a loss of what to do. Two weeks later (we still don't know how the cat nourished itself) the lucky feline managed to find its way back to the same open window and jumped back into his home. The honest truth is that on that day I witnessed the cat cry real tears of joy when he saw his owner again, water dropping from his eye into his fur. It is something I will never forget.

My point is, we only know a tiny fraction about other species behaviours - often something that is believed today is disproved tomorrow. I choose to believe that even insects could have individuality, could 'learn' from life experiences and may act on instincts passed down from relatives that have gone before them. After all, isn't that part of what evolution is? Often, mankind seems to think that insect anatomy is so alien to our own that they can't possibly learn from life events or have any individuality. I'm not convinced about that.

Regards,
Phil.

[ernie f]

I am no expert but I support your view. I have had many cats and dogs as pets in my time and they all had different characters, all showed emotions and all had dreams!

Now regarding butterflies, I did a quick look-up on Wikipedia to discover...

1: A butterfly has cerebral ganglia, Wikipedia says...

"Basal ganglia are strongly interconnected with the cerebral cortex, thalamus, and brain-stem, as well as several other brain areas (in humans). The basal ganglia are associated with a variety of functions, including control of voluntary motor movements, procedural learning, habit learning, eye movements, cognition, and emotion".

My comment - In other words it records procedural learning and habit learning and this can effect motor movements.

2: Some parts of the butterfly's brain do not modify during metamorphosis. Wikipedia says...

"The brain cells that aren't completely broken down are mostly the ones that send signals to the muscles to tell them to move. So even though the muscles in the caterpillar and butterfly are different, many of the brain cells that signal those muscles in the caterpillar will remain the same through metamorphosis and signal the new muscles in the butterfly".

My comment - So it is conceivable that the butterfly can react to a stimulus that it learnt as a caterpillar even though in the butterfly the result is different - ie the amount of wing-roll and what triggers it. It also suggests that although the wing-roll appears to be an habitual action in all Lycaenidae, there will be both species AND individual differences due to learning and inheritance.

[PhilM]

although the wing-roll appears to be an habitual action in all Lycaenidae, there will be both species AND individual differences due to learning and inheritance.

That's it in a nutshell Ernie, I think you've expressed the concept very well. This is just one of many unproven theories of course as to why Lycaenidae wing roll, but it is the one that sits most comfortably with me. It also allows for other observed triggers, such as wing rolling in the presence of a tiny fly, whilst nectaring, just after landing etc. It could be in part down to the individuality of the specific butterfly concerned (we could even give it a name - butterflyality, a play on personality, but that would mean inventing a new word ).

I wonder if we will ever be able to find out for sure, probably not until we as a species find a way to communicate with other species - not beyond the realms of possibility. I feel a song coming on - "if we could talk to the animals...talk to the animals...".

All the best,
Phil.

[Max Anderson]

I'm familiar with the wing-rolling behaviour of European lycaenids, and the mystery surrouding the function of this behaviour, so I've spent a fair bit of time reading through this topic a number of times. I've seen this behaviour in many other lycaenids in Africa and South America, and I wouldn't be surprised if it was found in all species.

Hypolycaena liara, Zambia.


I'm also aware that it's been recorded in a number of riodinidae (Hall,1998; Robbins, 1986), particularly those which have tails. There's also some research to show that moths produce extremely quiet ultrasonic sounds from wing rubbing (Nekano et al. 2008), which could also serve as a function of this behaviour, though in lycaenids, it's not specific to males.

It's interesting that many of the tail-less lycaenids have retained this behaviour, raising the question about whether it does serve as an anti-predator behaviour. I think the most plausable explanation for this behaviour is related to anti-predation. The bottom line is that controlled, experimental tests are needed to establish the true function of these behaviours.



Anyway, I'm here to throw a spanner in the works - below is a GIF of Zizula cyna, from Ecuador. I spotted this tiny lycaenid on a number of occasions, mostly active around patches of long grass beside paths in the montane forests. This 'swaying' behaviour was seen on 7 different occasions, all while wing rolling. I also observed them wing rolling without swaying, but never observed them swaying alone. Thought it would be worth sharing in case it brought any ideas forward..



Hall (1998) A review of the genus Sarota (Lepidoptera: Riodinidae) - https://journals.flvc.org/troplep/article/view/90133

Nekano et al (2008) Moths produce extremely quiet ultrasonic courtship songs by rubbing specialized scales - https://www.pnas.org/doi/abs/10.1073/pnas.0804056105

Robbins (1986) Independent evolution of the "false head" behavior in Riodinidae - https://repository.si.edu/bitstream/han ... sAllowed=y

[ernie f]

Max

Thank you SO much for your post. So much info packed into such a small space!

Firstly I was amazed at the species that sways while it rolls. That'll be something to keep me awake at nights thinking about. A 'Rockin and Rollin' Butterfly!

But more than this - your world-wide experiences made me think. If these butterflies are doing wing-rolls in Europe, Africa and the Americas, then this behaviour must have evolved a very long time ago. It couldn't really be plausible that different species of the same family so far flung from each other separated by wide oceans could have evolved the same thing simultaneously - at least I wouldn't have thought so. That leads me to the conclusion that it evolved before the last split of these continents, when they were joined in the single land mass known as Pangaea.

So I had to look it up. When did the continents split up? Wkipedia says...

Pangaea or Pangea (/pænˈdʒiː.ə/)[1] was a supercontinent that existed during the late Paleozoic and early Mesozoic eras.[2] It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of the Jurassic.

And how long ago have butterflies been around on this planet? Again Wikipedia tells us...

Butterfly fossils date to the Paleocene, about 56 million years ago.

So that means that although our oldest fossil butterfly that we have found so far is 56 million years old, butterflies as a whole must be over 200 million years old and had already started wing-rolling way back before then.

Is my logic sound on this? I am beginning to doubt myself.

[ernie f]

Further thoughts

Well my logic isn't toatally sound. Some butterflies migrate large distances, some are intercontinental. Some can get blown off course and maybe, if they get too high up in the atmosphere, get dragged by the jet-stream.

Europe, Africa and Asia are all actually connected landmasses anyway and even Asia and North America are almost connected at their northern-most point and indeed once were actually connected within human existance on the planet, so maybe we don't have to invooke Pangaea after all.

Nevertheless it's anazing to think that wing-rolling may be a global beahaviour.

[ernie f]

It's also amazing how many spelling errors you can make if you don't read what you just wrote at least once before submitting!!!

[KayG]

Another lycaenid for your wing-rolling list? I think this is a Black-eyed Blue (Portugal, in March), based on an ancient Tolman & Lewington plus euroButterflies.

Apologies: as I don't use YouTube, I've reduced the video below to a low-res GIF instead (works if you tap on it). Hope it's still clear enough.

I'd welcome confirmation or correction of the ID (should be enough detail in this pic here, I think)

[David M]

Hi Kay. Yes, you're right about the ID.