Brown Stains on Green Ornithoptera

[jhyatt]

     The green Ornithoptera males seem to occasionally exhibit a brown discoloration that is unique to those specimens (i.e., it does not occur in females or in Troides specimens).  I see it mostly in older specimens, such as the O. p. demophanes picured below.
     Has anyone ever made a technically competent study of the nature of this staining?  I've never seen such a study mentioned in any publication.
     I do not believe that this is merely the effect of oil from the body - the stains are completely unaffected by extraction with hexane, acetone, or ethyl acetate.  And any ofthese solvents will clear up oil-caused discoloration of iridescent scales, such as on, say, a female Speyeria diana blue hindwing.  Furthermore, oil stains usually seem to proceed from the abdomen into the hindwings, whereas in many cases, as shown in the photo, the stain seems to emanate from the thorax.
     Examination using a dissecting microscope reveals nothing - the scales in question do not appear matted, oily, or damaged.  They are simply brown, not green.  Is it possible that this is not a stain, but a "birth defect" that was present when the butterfly eclosed?  Does anyone possess a specimen which has become stained in this way since they obtained the bug?

     Surely someone somewhere sometime has elucidated what's going on when green birdwings become brown!

[jhyatt]

[Paul K]

I think it is water stain. Perhaps injected water for softening the wing's muscles. Brown stain are actually a demadge scales.

Paul

[jhyatt]

Paul,

I don't understand the term "demadge". Could you perhaps explain?

Putting water on a green birdwing scale area doesn't seem to leave a stain - I've done that. The scales are temporarily discolored, but recover their original color when the water dries.

Thanks,
John

[Paul K]

Jul 7, 2016 1:43:23 GMT jhyatt said:

Paul,

I don't understand the term "demadge". Could you perhaps explain?

Putting water on a green birdwing scale area doesn't seem to leave a stain - I've done that. The scales are temporarily discolored, but recover their original color when the water dries.

Thanks,
John

John , I miss spelled it should be damaged of course .
I have done that too by accident and it did leave brown stain.

[timmsyrj]

I only had this issue when injecting the dried papered specimens for setting instead of using a relaxing box, don't use boiling water and you shouldn't have the problem, I believe it's the diluted body fats under the scales, usually a result of capillary action when a hot fluid (in this case body fats desolved in boiling water) is drawn into small areas such as under the scales, when it dries the fats will leave a seal underneath and not allowing cleaning chemical ingress, rather like bitumen on roofing felts.
Chemicals will clean oil and fats on the top surface but not underneath.
Also as the scale colour occurs by refraction rather than reflection this will alter the colour, i.e if it was reflection you need a clean top layer of the scale but with refraction all surfaces of the scale (which is a minute prism) need to be clean to refract the colour.
Use water at around 60-70c and the fats shouldn't melt, just soften, it may take a little longer to relax but you should get a clean specimen.

It may also be caused by steam from the boiling water deforming the scale structure and causing a duller colour to be refracted


Rich

[Deleted]

I have seen 2 ornithoptera Goliath males with what looked like a small red stain on the forewings only, identical on both wings that on further inspection must be an ab, the specimen in the photo does look water stained to me.

[deliasfanatic]

I've had this occur in a number of old priamus (papered for 25+ years before setting), particularly demophanes. It seems that all of the latter are prone to this staining. I use cold water for injection and it happens anyway; in fact, if I remember correctly, I looked at the semi-softened specimens prior to injecting and the stains were already there.

[jhyatt]

Deliasfanatic,

My experience is about the same as yours - I have never, ever relaxed a specimen by injecting hot or boiling water. I put large-bodied species into a conventional relaxer for about 24-48 hrs to soften antennae and legs, and then if necessary I inject room temp water to complete the process. So at least in my cases, the staining has nothing to do with using hot water.
And I repeat that I have tried placing a large drop of water onto a wing, and it did not leave any stain when dried. Maybe Paul K and I are using water of differing quality - mineral content, pH, etc?
I strongly suspect that the stain is present before relaxing the bugs, but that'd be hard to prove without breaking a specimen to see. Has anyone with lots of Ornithoptera field experience ever captured a specimen with staining present? Live ones must get wetted by rain from time to time. Or does staining only appear in old dried specimens? Why don't female birdwings stain or get oily, whether inject or not? In most other butterfly families, it's the female which is far more prone to staining or oiling.
Perhaps someone could do SEM photography of some stained scales to see if there's any obvious mechanical difference in their structure. Timmsyrj seems to lean in this direction with his comment about something (water, fat, oil, etc) deformng the scale structure.
And yes, demophanes males appear particularly prone to staining. Four out of 4 of my males show some staining, and only one out of about a dozen poseidons has a stain. I've never seen brown stains on goliath or tithonus, etc - although victoriae males often are stained. It might be interesting to look at some really long museum series of these bugs and get statistically significant data on where it occurs.
Like a lot of Lepidoptera study, this topic is one where everyone (me included) has an opinion, but
no one has much hard data!

Cheers,
John

[deliasfanatic]

It seems a type of stain that's unique to priamus (and I suppose its close relatives), and as you've said, I've not found any way to remove it. I also have 4 demophanes males, 3 being IFTA specimens from the 1980s, and one from Richard Carver dated 1967. I've had one set for about 25 years; only last year, I finally pulled out the others for setting, and was unhappy to find that they were all stained too. Likewise, I think it was probably present prior to relaxing.

[jhyatt]

Sometime this fall I will be at the McGuire collection in Gainesville. If I can find time while there, I'll look at their priamus-group holdings and collect some data on the incidence of staining in different species and ssp. I seem to recall having seen the stains on croesus & lydius, but never on urvilleanus, for instance. And maybe I can talk someone into doing some SEM work on normal and brown scales.

Stay tuned,
jh

[timmsyrj]

You could well be correct guys, I have to say I've never noticed it on a specimen prior to relaxing ( mainly because I've never looked what with the wings being tightly closed ) and since I stopped injecting with boiling water and going with the relaxing box I have not seen it since (I have set a few hundred priamus specimens over the years), sometimes when injecting, I noticed the water coming out of the specimen was brown and left oily patches on the surface of the simmering water below and this had gone onto the wings ( like a typical water mark ) only after drying it left this stain.
Could it be the chemicals used to kill the specimen leeching out and discolouring the scales when they are injected.

I've never noticed it on females either but then they are brown, coloured scales not irredescent little prisms as with the males, have you noticed it on the males black areas?

Rich

[timmsyrj]

Just having a closer look at your photo you can actually see perfect, un damaged bright green scales in the stained areas, quite how this happens I don't know, I would imagine a water mark or stain would be on all scales in this area.

Rich

[jhyatt]

Rich,

Yep, the staining is often uneven in the green areas. Looking at actual examples, I can't see any sign of it on the black sections nearby, but it'd be hard to see there anyway. My suspicion is that it only visibly affects the iridescent scaling, but that's a guess.

I wonder how the market collectors kill their priamus? Injection, or just pinch, paper, and let them die slowly? Or does something come out of the thorax if the specimen is pinched really hard? Some Arctiid moths do that... Come to think of it, I bet most commercial specimens are reared, not wild-caught. Wonder what birdwing meconium would do the the green scales, if it got on them?

I am about 90% certain that I have seen brown staining before relaxing specimens - it often shows up on the underside too. But it's been a while since I've handled any birdwings, and my memory might not be perfect.

Regards,
John

[nomad]

The staining must be due to dampness or water. I have seen lots of old series of museum priamus with no colour loss. Native breeders usually take the pupa to dealers or kill them on the spot.  Both would always inject a large species never pinch them. It is in their interest to do a perfect A1 job.