Subject: Re: Displaying moths -- help wanted

From: Thomas L Orourke <[email-masked]>
Date: Mon, 9 Dec 1996 22:27:56 -0500

In a message dated 96-12-09 12:28:14 EST, you write:

<< Colors fade because chemicals
 are destroyed when the species dies out. >>

It seems quite clear that fading is to to chemical alteration following
death,the only alternative I can imagine being evaporation of intact chemical
coloration compounds,a possibility in theory.Wouldn't that be something if in
fact operative.Assuming this not to be true,however, factors other than light
 almost certainly play a role.The prime example of this that comes to mind is
the very rapid decoof bright coloration of thorax and abdomen of
Odonata,i.e.dragonflies ,often within an hour or so upon death when kept in
the dark.Granted,these are not leps,but the changes must be  due in these
fabulous creatures to the lack of oxygenation and/or increase in acidity of
the circulatory system or indirect effect thereof  such as
,theoretically,decreased potassium in cells as H+  builds up in cells.This
may cause secondary or tertiary molecular alteration with resultant changes
in light diffraction.The UV and/or other wave lengths of light may act in
similar fashion on pigment structure over a longer time course. These are my
theories based on my background in biochemistry and pathology.I have no proof
on entomologic grounds but in humans these principles apply in many ways.

---

From: Michael Gochfeld <[email-masked]>
Date: Sat, 14 Dec 1996 12:36:12 -0500

This follows on Tom Orourke's remarks from last week.
Assuming that the structural components of the colors do not change,
the changes must involve pigments.  Some reactions involve chemical
reactions that proceed very slowly at room temperature but may be
accelerated at high temperatures (that's why it's recommended to keep
film and color slides in cold storage).  Photochemical oxidation is
another common occurrence with organic pigments.  And high heat can
produce dramatic results.  Hearing that some bird carotenoids changed
color with heat, I held a match close to the purple throat of a cotinga
specimen and was chagrined to see it immediately (and permanently) flash
to orange. It explained perhaps why there were orange "mutants" in some
of the trays. Maybe they had been skinned to close to a campfire.
        Perhaps experimenting with certain glass coatings that screens
out UV light with minimal effect on visible rays has been done.

Mike Gochfeld