Warming up for flight

[Doug Dawn]

After I wrote this, I got back to my procrastinated Spring cleaning and found some small dried moths in a one corner.  Your question completely changed the day, though, because I looked at them
imagining all kinds of theories relating to the Lep branching of the evolutionary tree between moths, day flying moths, butterflies and skippers, and how selection has given us the impressive cast
of characters we have today.

Some of the littlest moths look like tiny wrapped tubes, the way the wings are repetitively folded around their bodies.  I imagine the R-factor (the rating for buying attic and wall insulation) of
them is quite high on their scale of interest for minimized heat dissipation.  On the other hand, some butterflies wings barely touch their bodies, to minimize this insulatory ability the packed,
folded wings moths have.  So all this is quite relevant to why we say butterflies generally can't fold their wings and many moths are designed to do exactly this... and more deeply and arguably,
relevant to the question what is the difference between a butterfly and a moth.  Throwing the latter question away, many of the explanations of diffferences become simplified to - forget the poorly
defined butterfly/moth debate - and think logically at what ambient condition / heat regulation system is each  Lep designed for.  Those evolutionary considerations lead to our perceptions of a
category of Butterflies and of Moths.  Best.  Doug Dawn.

Doug Dawn wrote:

> Sunsol Daniels wrote:
>
> > Why do butterflies have to sit in the sun to warm up, but moths can fly
> > without sunshine?
> >
> > Sally
>
> Hi Sally,
>
> Nothing too surprising when you think about it - moths are not optimized in
> an evolutionary sense for the temperatures butterflies are if we try to
> generalize.
>
> Generally, I could think heat is regulated as follows in the insect:
>
> 1.-  Free source - Solar power.  The sun and warm rocks, etc. where wings
> act as solar collectors  Recall butterflies can't fold their wings if they
> want to, though moths typically do due to their niche optimization.
>
> 2.-  Internal source is the friction created in the contraction of flight
> muscles (just like in humans, we shiver to keep warm and the molecular and
> macro resulting friction in our muscles converts fuel into heat).  This has
> been called "shivering thermogenisis".
>
> 3.- Another internal source of heat, especially for smaller insects are the
> organs which increase "blood" temperature and "heart" which sends it to the
> thorax where the flight muscles are.
>
> 4.- In butterflies, a lot more heat is lost in the abdomen than moths since
> the moths typically have a better abdominal heat exchanging system to
> deliver heat to their "blood".  In this case many moths have a more
> efficient heat exchanger inn the abdomen which actually flows counter
> current and provides heat to the thorax.  The thorax temperature is what
> determines if the Lep flies since that is where the flight muscles are.  See
> NOTE for further information on efficient abdominal heat exchange.
>
> 5.- As any air conditioning engineer might point out, "insulation" is
> important.  "Regional endothermy" is the so called trait giving the ability
> to maintain the little area of flight muscles warm.  Perhaps the "Thermos
> effect" might be an alternate term.  Moths can be better insulated than
> butterflies, but also see NOTE.
>
> NOTE:  For more information on the benefits of counter current flow, look up
> the Lorenz cycle (vs. Carnot) and check out my US patent #4,926,650 if you
> want to understand better the efficiency for counter current heat
> exchangers, where a practical method is described for achieving this for
> industrial application.  But it basically says, when you don't use pure
> fluids, the efficiency can be higher when the fluid to be heated and the
> fluid to be cooled are closer in temperature.  Being closer in temperature
> requires counter current flow of fluid mixtures:  i.e.  Heated fluid from
> the abdominal matrix flows into the warmest part of the heat exchanger
> between itself and the zone in it preparing the "blood" for thorax.  As the
> transfer occurs within the abdomen, the temperature difference is minimized
> and matched.  This minimizes heat escape, but a discussion like entropy are
> off topic and has already happened once.  As this relates to the insect, the
> exit end of the abdominal heat exchanger has maximized the heating ability
> of the "blood" now destined to supply the thorax.
>
> http://www.patents.ibm.com/fcgi-bin/any2html?FILENAME=%2Fcache%2F50%2F66%2F4926650.tif&PAGE=3&USER_HTML=%253CA%2BHREF%253D%2Forder%253Fpn%3Dus04926650__%253EOrderPatent%253C%2FA%253E&SCALE=0.35
>
> I am guessing that butterflies do not have the counter-current heat exchange
> option, at least during warm days, because at that point heat is a problem
> to be dissipated any way it can including by the most inefficient heat
> transfer.  I am practically sure someone knows experimentally this but if
> not it would be a good subject for a research paper.
>
> Keep in mind there are butterflies that do not even fly in the Sun
> (crepuliscars like from the Smyrna genus).  And moths - like Sphinx moths,
> which specifically have evolved to fly in the warm season do not have the
> heat exchanger setup described above.  They effectively have efficient
> cooling exchangers to quickly dissipate the heat buildup expected.  The
> "aorta" is much like a set of cooling coils to dissipate heat  So as you can
> see they are all in their individual niches and generalizing could cause
> problems.  I suspect that day flying moths like Urania have also evolved the
> generalized butterfly system.  Finally note, that moths can't just get up
> and fly when it is cold and dark.  They have a revving up period which can
> be as much as a half hour while the system described above heats them.  Not
> a whole lot unlike butterflies basking in the morning sun which accomplish
> the same means...And that same moth which does such a good job at on cool
> season nights probably isn't around in warm seasons since it would "burn
> out".  That brings up another interesting question:  What Lep has the
> broadest range of temperature operation and what is its system like?  That's
> a good one for an expert.
>
> Hope this is helpful for your question and maybe someone else can clarify
> further.  Best wishes.  Doug Dawn.
> ________________________
> Douglas David Dawn
> http://www.geocities.com/RainForest/4048/
> Dawn Photo
> http://members.tripod.com/dawnphoto/
> N.  25º 37.408'
> W. 100º 22.003'
> Altitude 910 meters
> Sylvania Pinus-Quercus

--
________________________
Douglas David Dawn
http://www.geocities.com/RainForest/4048/
Dawn Photo
http://members.tripod.com/dawnphoto/
N.  25º 37.408'
W. 100º 22.003'
Altitude 910 meters
Sylvania Pinus-Quercus

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