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This question already has an answer here:

If rideable-sized butterflies/moths were possible, how might environmental factors (e.g. climate, temperature, altitude) affect them? If the square-cube ratio issue could be overcome, and it could find enough to eat, where and how would this creature live?

I'm envisaging this giant butterfly creature to be pretty rare - so there aren't hordes of tank-sized caterpillars roaming the countryside - and ideally originating in a fairly remote, mountainous region. It would also need the ability to survive at other altitudes/in other climates. As a rideable creature, it would also have to be capable of carrying one adult male (plus light baggage), maybe two adults at a pinch.

Questions:

ENVIRONMENT - How would it react to different climates/temperatures, beyond its natural mountain habitat? (Maybe a lower altitude would give greater oxygen, and be helpful? But a humid coastal environment could cause problems for wings??)

LIFESTYLE - How would it sleep/rest? (I actually don't know if butterflies/moths can fold their wings up to make them take up less room, or if their wings have no more flexibility than simply flapping to make them fly!)

If you've got any ideas for any of these questions, or any issues that I haven't thought of, that would be great!

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marked as duplicate by MichaelK, L.Dutch, Aify, Amadeus, adaliabooks Sep 4 '17 at 21:10

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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    $\begingroup$ Helpful; worldbuilding.stackexchange.com/questions/78419/… $\endgroup$ – adaliabooks Sep 4 '17 at 13:46
  • $\begingroup$ Thank you! I've had a look at that one, and was wondering a bit more about potential evolutionary possibilities for the giant butterfly/moth creature (I'd prefer not to change the environment of my world, or make all my humans really tiny!) It is definitely helpful though. $\endgroup$ – K. Price Sep 4 '17 at 13:49
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    $\begingroup$ The policy is to focus on one question per post. You explicitly state that you have several questions. Please edit your post to focus on one question per post and ask the other ones at a later time after you get feedback for the first one. Also Can you simply scale up animals? might be interesting for you. $\endgroup$ – Secespitus Sep 4 '17 at 13:52
  • $\begingroup$ @MichaelK - hopefully the edits have clarified a bit! I'm less interested in the feasibility of the creature's existence, and more about how external factors might affect its lifestyle and areas it could survive. $\endgroup$ – K. Price Sep 4 '17 at 14:05
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The main limiting factor would be an oxygen concentration. Here you can read about how insects breath.

enter image description here

In short, there are tiny tunnels all over their body surface called tracheae. Since there are no lungs for insects, trachea work both as a "nose" and lungs. This empty tunnels go deeper into the creature's body, splitting and branching multiple times pretty much like our capillaries do (I mean, visually, not functionally :) ). For oxygen to reach the deepest dead-ends of trachea you need highest O2 concentration in the atmosphere.

There is even a theory that larger insects existed about ~300 million years ago particularly because of 35% oxygen concentration at that time opposed to 21% present time.

I'll agree that mountains won't do well in this case, I suggest putting them somewhere near hills so that they will be protected from winds and still be not far above the sea-level.

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First: how big to carry 2 people. Tandem hang gliders can carry 2 people so that is a start.

From http://www.adrenalinepages.com/sportindex/sportpages/Stories/stories_hang_glid.asp?sp=20

Solo hang gliders average 145 - 150 square feet, and tandem gliders are almost twice as large at 210 - 220 square feet with a 37-foot wingspan.

The problem with big bugs is oxygenation, as @user2851843 (catchy name!) points out. The diffusion system insects use does not scale up well.

Your butterfly has something that most large creatures do not: a tremendously high surface to volume ratio. It is mostly wing. I propose that your butterfly make an end run around respiration by generating its own oxygen (and calories!) via photosynthesis.

Pulling math from How to build a race which uses photosynthesis?

•I found average sunlight power at Earth surface in 164 watts / m2 / 24 hours •I found photosynthetic efficiency (conversion of energy to biomass) of 3 to 6%. Let us use 6%. 6% of 164 is 9.84 watts / 24 hours •1 watt = 0.86 kcal. 0.86 * 9.84 = 8.4 kcal.

The butterfly is roughly 20 square meters and so would generate 168 kcal. But really we want the oxygen. I found here that

http://www.science20.com/robert_inventor/could_astronauts_get_all_their_oxygen_from_algae_or_plants_and_their_food_also-156990

In the early BIOS-1 experiment they had already shown that you can produce all the oxygen you need for one person from just 20 kg of water and algae (that's 0.02 cubic meters), spread over 8 square meters of surface area.

So: scale up your butterfly to hang-glider size and make an endrun around the inefficient arthropod respiration system with onboard chloroplasts generating oxygen over the big surface area.

I suspect your butterfly would not be very energetic. Probably it would glide at altitude most of the time, soaking up the rays.

GIANT GREEN BUTTERFLY
Or at concerts, soaking up the love.

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