Correct Wingspan Measurement .

[Silverstreak]

Which is the correct definition of "wingspan" ??

1. The length of the straight line between the two forewing tips.

2. The expanse of the butterfly obtained by measuring from the centre of the thorax (the pin) to the tip of the forewing and doubling the result.


:cheers:

[Painted Jezebel]

My understanding is that both methods are used.

Method 1 is the 'wingspan'.
Method 2 is the 'forewing length' (but do not double, it is used for a single wing only).

Whichever is used should be made clear. I prefer the first, but I see that the second one has become more popular in recent years.

[Commander]

I saw Peter's FB discussion. Evans method of taking the measurement from the pin to the wingtip appears to be referring to the "forewing length" and not wingspan. Fleming uses that in his book as well.

As Les said, there is no doubling of forewing dimensions in taxonomic convention. It is taken as a single measurement from pin (or in some cases, base of wing at the thorax) to the tip of the wing on the same side.

Wingspan is the other dimension used in some cases where the dimension is taken from tip to tip in a straight line. E.g. the wingspan of a plane as referred to in the Jane's military books adopt this convention.

The use of wingspan in butterflies, however is less accurate and depends on the way the specimen is set. Conventionally, specimens are set with the termen of the forewings at 90deg to the body of the butt. However in recent years, many collectors are setting the wings higher up, often up to 5deg beyond horizontal. This makes the "wingspan" dimension vary between the set specimens, depending on how they were set.

In the measurement of forewing length (which should not be doubled), there is no confusion, and does not depend on how the specimen is set.

Perhaps Seow, Steven and Teo can share their opinions.

[Commander]

Sunny, perhaps when everyone has given their views here, you can convert all these comments into a graphical summary. This would make it clearer as a 'picture paints a thousand words'. :)

I googled some early researchers' specimens, and if we looked at how Wallace set his specimens (which actually were not set at all), the pinned specimens had their wings drooping down as in the field. Later entomologists used the wingtip to wingtip measurement for "wingspan" with the comment that the wings should be sent with the termen perpendicular to the body for this to be standardised.

In WA Fleming's "Butterflies of West Malaysia and Singapore" all the dimensions are of the "forewing length" convention. He did not use wingspan. Forewing length is less subject to variations as it is a single simple measurement that is independent of how the specimen is prepared after killing.

Dr Kirton also uses "forewing length" these days. In some cases, where there are two dimensions, researchers have been known to use trigonometry to convert forewing length to wingspan (using simple geometries of a triangle)

Anyway, Peter S may not be totally correct to use the "pin to wingtip and doubling it" method to arrive at wingspan. I don't have Evans' book to refer to, so I'm not sure what Evans meant when he said that wingspan is taken by that method.

A good discussion going on, and we should all arrive at a common convention and definition to this.

[Painted Jezebel]

It appears that I may be even more old-fashioned than I thought. I have just checked some of my old books, and even Higgins & Riley, in their Field Guide to the Butterflies of Europe, published in 1970, used the 'forewing length (fl)' method.

It looks like I will have to change, though, as I said earlier, I prefer the 'wingspan' method, as there is less likelihood of me damaging the specimen (I have a natural slight shake), and there is no need to have the measure near the specimen.

I fully accept the problem mentioned about this method, with differing styles of setting specimens.

The only question I would need to ask about the 'fl' method is how the measurement is taken, from the pin in the centre of the thorax or where the wing meets the thorax, as these would give differing results?

[Psyche]

Wingspan is measured from forewing tip to tip in a set specimen.

Butterflies are set with the dorsums of both forewings in a straight horizontal line.
In case of species with strongly bowed forewings eg Euploea, vein 1b is used as the horizontal marker.

The tip is where the costa meets the termen, and would be easily seen on the underside in butterflies with angulated or extended forewings.

I don't think forewing length is measured from tip to a pin in the middle of the thorax , but from base to tip of the forewing.
In the case of a large skipper, measuring to the middle of the thorax will add a couple of mm. to the total length of the forewing.

In well-set specimens, both methods are admirable in conveying the size of the specimens at hand.

Scientific methods required precise measurements, and all critical works by entomologists employ the forewing lengths for comparison.

TL Seow:cheers:

[Commander]

Oops! I meant dorsum rather than termen.:embrass:

But my understanding of wingspan is the same as Les and Seow. That's the taxonomic convention that's used by most lepidopterists.

Seow, the debate was raised by an Indian enthusiast on another Facebook page. Perhaps Sunny can cut and paste his comments here to give a context to his first question in this thread. He apparently questioned another author based on Evans' definition of wingspan. I'm not sure if he made that reference in thr correct context as what Evans intended.

Whenever I measure forewing length I also take it to mean the base of the wing to the wingtip on the same side of the butterfly. As you said, there will be a difference of a few mm for fat-bodied butts like the Skippers and the Birdwings, if taken from the pin.

[Silverstreak]

The reason for me to raise this question is from Peter Smetacek's post where he query the author of the book "Butterflies of Peninsular India" on the confusion of measurement the author used.

If I am not wrong , "Butterflies of Peninsula India" use species measurements from " The Identification of India Butterflies" by Brig. W.H. Evans (1932) which used Forewing Length x2 ........but the "Butterflies of Peninsular India" author explained it as wing Tip to Wing Tip measurement.


" The book where these statements quoted are made is "Butterflies of Peninsular India" by Krushnamegh Kunte, edited by Madhav Gadgil, with a Foreword by Prof. E.O. Wilson, published by the Indian Academy of Sciences at the Universities Press.

The measurements of wingspan mentioned in the sentence excerpted for the question as well as the wingspan in millimetres quoted for all the species in the systematic section of the book are from "The identification of Indian butterflies" by Brig. W.H. Evans (1932).


"There is a considerable difference between the definitions of wingspan in the two books:

In K. Kunte's book, it is the straight line between the two forewing tips, as depicted in the diagram on page 11.

Brig Evans, on the other hand, stated on page 27, "...and then in brackets the expanse of the butterfly in millimetres, obtained by measuring from the centre of the thorax (the pin) to the tip of the forewing and doubling the result:..."

When one considers that there is only one measurement in butterflies, i.e. the wingspan and this has been misrepresented so that everyone who started butterflying with this book has been misled (note that no one on this forum was aware of this major TWADDLE), one is left aghast.

When one further considers that the sole author of what purports to be a reference book wrote the entire book without knowing how to measure a butterfly yet quoting measurements and drawing comparisons and even going to the trouble of drawing a diagram to illustrate his ignorance, one is left breathless.

Besides, the book has a prominent editor and a famous international zoologist wrote the Foreword. Add to this that I pointed this twaddle out in the review stage but, so deeply convinced was the author that he was correct that my comment was clearly ignored. I hope you will better understand why I am sceptical of taxonomic changes proposed by this author....haha!

[Psyche]

I am begining to see what is at fault here.

In the early days, butterflies were not set and dry in a fixed position, and the wingspan is that of the wings in their fullest extent, as in the outstretched wings of a bird. Thus Evan placed as wingtip to middle of thorax x 2.

When Wallace mentioned the wingspan of the birdwing O. croesus as 7'' across he meant the wings in the flight position.

When butterflies are set in a particular way, entomologists started to quote wingspan in the set position or wing expanse.
Perhaps this should be qualified although in butterfly books it should be a non-issue.

In layman's term a person can say the butterfly have a wingspan of about 3 inches, meaning in the outstretched flying position in the field, and he is absolutely correct.
If he can not call it wingspan, what else can it be from wingtip to wingtip.

TL Seow:cheers:

[Painted Jezebel]

I read Sunny's quotations, and found out their origins, which immediately made me take note. When I want to think, I go to a pub(It always works)!! I, very quickly understood what the problem was, and Seow has got it closely right.

I will give the answer properly tomorrow when I can word the response properly. In some respects, neither (or both) are wrong, but I will explain.

[Psyche]

I did a simple test.

The wing expanse of T. brookiana albescens as stated in the text of C&P4 is 6 to 6 3/4 inches.

Now there is a pair of natural size images of this species near the front.
By measuring this with a tape, I get the following results.

Wingspan male 6.3 inches.
Wingspan female 6.2 inches (thorax is a bit squashed.)

These are well within the limits stated.

By measuring from the forewingtip to middle of thorax I get 3.75'' x 2 = 7.5 inches.
Likewise for the female.
This is well outside the limits if C&P4 had meant wingspan in the flight position.

Admittedly there are butterfly books which quote wingspan in the flight position but these are not serious works.

TL Seow:cheers:

[Silverstreak]

The gist of the argument is that: The measurement by Evan for wingspan was doubling of Forewing Length (FL) . If these data were used as wingspan (WS) in "Butterflies of Peninsular India" by Krushnamegh Kunte, and illustrated as wing tip to wing tip wingspan( with dorsums horizontal) , all the wingspan figures in the book are all WRONG.

As show in the diagram "Doubling of FL" is NOT equal to Wingspan.

Doubling of the FL as the wingspan make sense to me , as it is closer to the natural way a butterfly flutters . I have not seen one fluttering with dorsum horizontal in the wild ! :bsmile:

If one is to use FL to calculate the wingspan, the measurement will have to be from the centre of the thorax. Wingspan for aircraft is measured from wing tip to wing tip including the fuselage. For variable sweep wing aircraft like F111, F14 etc ....that is another story.

http://i13.photobucket.com/albums/a288/SunnyChir/Bin/SNAG_Program-0188_zpse1fa8deb.jpg

:cheers:

[Psyche]

The author erred in quoting Evan's formula. It is not the equivalent of the modern 'wingspan'.
Evan's formula was set at a time when there was no proper standard for set specimens.
Once a standard setting was accepted, it become easier to compare sizes.

Wingspan means the span of the wings from end to end (not necessary tips if there are protruding parts).

It is easy with aircrafts, birds. beetles.

With butterflies they are two set of wingspan.

The wingspan quoted in butterfy classification works is the span in the taxonomically set position.

The other wingspan is the natural flight position(=Evan's measurement) is sometimes quoted in butterfly books for the general public.

TL Seow:cheers:

[Silverstreak]

Seow ,

The author Krushnamegh Kunte of the book "Butterflies of Peninsular India", use Evan's "doubling of Forewing length" data as wingspan " and illustrates these "wingspan data " with the modern day dorsum horizontal measurement.

Peter Smetacek is the one that highlighted these wingspan figures are wrong and quote from Evan's book that Evan used 2X FL.

[Commander]

Just got back from a short trip up north. No butt shooting though... ;P

I have Kunte's book, which I attach the "offending" page for reference so that we know what we are talking about.

Peter's point is that Kunte cited wingspan correctly in the diagram below, but the taxonomic data for all the butterflies in his book were based on Evans' definition. Peter is right, in that, if Kunte defined "wingspan" as is shown in his diagram, but used Evans' data of "wingspan", then all the dimensions would have serious inaccuracies.

From an example in the book, cross-referenced to Fleming's book
It is a case where based on Kunte's error e.g. the "wingspan" of a Common Mormon is stated as 90-100mm. Fleming recorded the "forewing length" as 45-50mm (which is probably somewhat similar to Evans' definition). So taking data from Fleming/Evans source, Kunte probably doubled it to arrive as his "wingspan". This would overstate the wingspan of the Common Mormon as larger than what the standard deviation of this species would naturally be.

We can see where the error is. In my book, my definition of "wingspan" is as discussed above - wingtip to wingtip and I arrived at 70-85mm. For those species in my book where I did not have actual specimens, I interpolated the "forewing length" data based on trigonometry to arrive at a more accurate dimension for the "wingspan" of the species.

So, Sunny, you can tell Peter that I agree with his opinion about Kunte's error. :)

[teotp]

In Evan's book (The Identification of Indian Butterflies, 1932, page 27), he wrote: "...the expanse of the butterfly in millimetres, obtained by measuring from the centre of the thorax (the pin) to the tip of the forewing and doubling the result: a more modern method is to give the length of the forewing from the base to the apex." Evan did not mentioned double the result of the measurement from pin to the tip of forewing = wingspan.

Most of the scientific papers and books (Vane-Wright & Yata, 2010; Yata, 1989, Fleming, 1991; Tennent, 2002, Yata et al, 1985; Braby, 2009) use forewing length (FL) instead of wingspan. The measurement of FL is from the base to the apex and not from the centre of the thorax (where the pin is inserted) because we are measuring the FL and not FL + 1/2 thorax width(as Soew pointed out that scientific work must be precise and accuracy is very important.).

Teo T P

[Painted Jezebel]

It appears that I need not fully explain what has happened, namely a change in the understanding of what 'wingspan' means, you have done this already now.

The Venerable Brigadier was correct in that the widest span between the forewing apexes(plural ?) is as he describes, though he uses the word 'expanse', not wingspan. However, most specimens are set, and over time (certainly by the 1960's) wingspan got to mean, what is now, the current thought which most, if not all, professionals use.

I was not aware that Evans had also mentioned the forewing length method.

I do not have a copy of Kunte's book, but if he illustrated what he means by wingspan, and then uses a different formula, then that is a bad mistake. I think Peter went slightly over the top in his comments (probably annoyed at being ignored), and in doing so actually made a mistake himself, when he stated that there was only one way to measure the size of a butterfly, he forgot winglength.

[teotp]

A recent paper (2012) by Prof. Vane-Wright mentioned forewing lengths but not wingspan.
I sent Dr. K. Kunte an email asked him about how he measure the wingspan and hopefully he will answer my questions.

Teo T P

[Commander]

I do not have a copy of Kunte's book, but if he illustrated what he means by wingspan, and then uses a different formula, then that is a bad mistake. I think Peter went slightly over the top in his comments (probably annoyed at being ignored), and in doing so actually made a mistake himself, when he stated that there was only one way to measure the size of a butterfly, he forgot winglength.

A copy of the page quoted by Peter is attached in my post above yours. The issue that Peter was debating, was that Kunte was correct in depicting and defining what he meant by wingspan in his diagram, but he used Evans' measurements for the individual species. Hence this creates an erroneous overstatement of the real wingspan of most, if not all, the species in the book. This is because Evans' measurements were not referring to wingspan, but wing expanse.


A recent paper (2012) by Prof. Vane-Wright mentioned forewing lengths but not wingspan.
I sent Dr. K. Kunte an email asked him about how he measure the wingspan and hopefully he will answer my questions.

There are also quite a bit of disputes across various individuals in the Indian community. Already, on their FaceBook groups, one can sense that there are a number of disagreements amongst the experts.

Peter Smetacek, who's a prolific author of many papers, has "exposed" the mistakes of other experts like Dr Kalesh and Dr Kunte amongst a few others, and tends to be rather unpopular for his straight-shooting comments. The debate will continue, no doubt, but we will probably be able to learn some new things from them once in awhile. Personally, I stay out of their disagreements and just watch by the sidelines. :)

[Commander]

How the debate continues, for the benefit of those without FaceBook access to the Indian pages.

Blaise Pereira On which page in KK's book is it mentioned that the wingspans in the book are from Evans (1932)..... ?????

Peter Smetacek Hi Blaise; by "KK" I presume you mean the author of Butterflies of Peninsular India, Krushnamegh Kunte? You are correct, I could not find it mentioned anywhere that the wingspans in the book are from Evans (1932)... could you confirm this for me, please, in case I have by chance missed the mention somewhere? Sorry to put you to this trouble.... :)

Blaise Pereira If it is not mentioned that wing spans are from Evans (1932), then his not using the same definition for wing spans as in Evans is Ok???

Peter Smetacek Blaise, you suddenly sound like a rather different person. However, it is an interesting question you pose. As in a mathematical problem, the "given" part is that the definitions of wingspan differ in Evans and Kunte. The second "given" is that throughout both books, the figures mentioned for the wingspan of individual species is identical. Since Evans was published long before any of us was born, it is safe to assume that the original set of measurements was in Evans.
Now, if you assume that Kunte actually measured a collection of butterflies and came up with the identical measurements as Evans USING A DIFFERENT MEASURE FOR WINGSPAN, then he must be singularly incompetent in using a ruler.
The second possibility is that he has used the measurements in Evans without acknowledgement, which attracts a much more serious charge than twaddling. Since he is a young man at the beginning of his career, I would urge you not to follow this charge up, since the careers of others have been wrecked because of such a charge.
The third, and least serious possibility to explain the matter is the route I have chosen, that he simply did not bother to discover how to measure a butterfly before setting off on his voyage of assertions and assumptions.
If you want, you are free to follow up the second charge, but I would not recommend it since he is still young and inexperienced.... give him a chance, i say.

Blaise Pereira So I can expect the points fr Twaddle no. 2 or hv u already allotted it to some one else????... :-) .. Also I was wondering if the 1st twaddle was bought to his notice before publishing, why did he not correct it.... or is it that it was overlooked and only noticed after the book was published.... in that case it is ok fr me....


Peter Smetacek Blaise, I cannot quite understand what you are trying to say... do you think you will be able to enunciate it more clearly in the morning? If so, no problem, we can wait.
For Twaddle Number 3, a point each go to Zdenek, Sunny and Ajith for their replies. Unfortunately, there are no points for asking questions, regardless of how many interrogation marks you use.....
Ashok has a point from Twaddle Number 1, but for Twaddle number 2, no one got any points.
Everyone is equal at this point...

Kishen Das I am still not able to get over the wingspans because I copied the wingspan measurements in my Kannada book "ChittegaLu" from "Butterflies of Peninsular India" :-(((. Bad move. I will ask Dr. Kunte about this and get back to this group. I still cannot believe Dr. Kunte can make such a big goof up about basic measurements. If it happens to be true, I will throw away all my 4 copies of that book and remove the reference from flutters. One more twaddle at the website level is the visitor count stats of IFB. The way count is calculated in IFB website is any click on any page adds +1 to the overall count. So, if a user happens to click on say 100 pages it would add +100 to the overall visitor count, giving the perspective that 100 unique users has visited the site. If the user re-visits the website the next day and clicks on another 100 pages, there would be another +100 to the count. So, now you have +200 added to overall count of visitors by just one single user browsing the site over a period of two days. And there are so many software bots that are trying to post an ad into your website which will also keep adding +1 to the overall count, as you are counting the clicks. Most of the US traffic that you see to flutters site are all software bots and not real persons. Ideally one should track the IP addresses and each IP address should add just +1 to overall count. This is what being used in the flutters website. So, unless your internet provider is generating different IP addresses each time you connect to internet, no matter how many times you visit the flutters website and no matter how many pages you visit, the count will not increase as most probably you are the same visitor re-visiting the site. Again, this was told to Dr. Kunte more than a year back but it was completely ignored. After this, I stopped believing his stats. I am more hardcore and passionate when it comes to stats related to Computer Science. Anyway they can still go back and fix the visitor count issue unless they want to feel good on false stats !!!

Kishen Das I have asked Dr. Kunte to clarify the claims of Peter Smetacek regarding Wingspans in a personal mail ( As Dr. Kunte is not available in this forum or on Facebook). I happen to be the biggest ever fan of "Butterflies of Peninsular India" and I myself need this clarification. This group will be informed once I get a response. If Dr. Kunte is right then Peter Smetacek's post will be removed in this forum and an apology post would be required from Peter Smetacek for the wrong accusation.

[Psyche]

Wingspan and wing expanse are the same.
In Evan's book the author state 'expanse' for his pin in mid-thorax to forewing tip x 2 measurement as pointed out by Teo.
In C&P4 in the text of T. brookiana & helena wing expanse is used for the span in the set specimen.

The problem is different authors use wingspans differently in their books. If they are not careful, the diagram prepared by the staff do not matched what they say.

AS an example. I have a book titled 'The Illustrated Encyclopedia of Butterflies' (1993) by Dr. John Feltwell.

Under 'Size' he states 'The wingspan is the distance between the tips of the outstretched forewings. This is a little larger than twice the forewing length since it includes the width of the thorax.. figure given is for maximum size of the female..'

This book featured set specimens, each with a little black silhouette of a set buttefly and a line across the forewingtips with the span in inches/mm.

The spans given varies widely though most appeared to follow what the author intended eg. Great Mormon (Papilio memnon) 150mm. but T. brookiana175mm. which is low.

TL Seow:cheers:
PS. This example is somewhat like that in Kunte's book.

[Silverstreak]

Seow,

Just to clarify the term used on the statement in 'The Illustrated Encyclopedia of Butterflies' (1993) by Dr. John Feltwell:

"'The wingspan is the distance between the tips of the outstretched forewings. This is a little larger than twice the forewing length since it includes the width of the thorax.. figure given is for maximum size of the female..'

Does the "outstretched forewings " meant the taxodomic approach of having the forewing dorsums set perpendicular to the thorax or a wing position that would register it its maximum expanse of the forewing length ?

The reason I am asking is : If the position of the forewing is positioned to sustain the maximum distance horizontally , the measurement will be very close to the " Forewing Length( from centre of thorax) x 2 " approach, with slight variation to the width of the thorax due to the angle adopted to take the measurement.

Thanks!

[Psyche]

Seow,

Just to clarify the term used on the statement in 'The Illustrated Encyclopedia of Butterflies' (1993) by Dr. John Feltwell:

"'The wingspan is the distance between the tips of the outstretched forewings. This is a little larger than twice the forewing length since it includes the width of the thorax.. figure given is for maximum size of the female..'

Does the "outstretched forewings " meant the taxodomic approach of having the forewing dorsums set perpendicular to the thorax or a wing position that would register it its maximum expanse of the forewing tips ?

The reason I am asking is : If the position of the forewing is positioned to sustain the maximum distance horizontally , the measurement will be very close to the " Forewing Length( from centre of thorax) x 2 " approach, with slight variation to the width of the thorax due to the angle adopted to take the measurement.

Thanks!

What it meant is with the forewings stretched horizontally to give the maximum span. This is roughly the flight position though it is not really so.

It is thus: forewing length plus thorax width plus forewing length.

TL Seow:cheers:
PS. It is the same as Evan's measurement.

[teotp]

There are also quite a bit of disputes across various individuals in the Indian community. Already, on their FaceBook groups, one can sense that there are a number of disagreements amongst the experts.

Peter Smetacek, who's a prolific author of many papers, has "exposed" the mistakes of other experts like Dr Kalesh and Dr Kunte amongst a few others, and tends to be rather unpopular for his straight-shooting comments. The debate will continue, no doubt, but we will probably be able to learn some new things from them once in awhile. Personally, I stay out of their disagreements and just watch by the sidelines. :)

Thanks Khew for your comments and also posted the debate between Blaise Pereira, Peter Smetacek and Kishen Das.

From their debate it looks like they don't have any evidences that Dr. Kunte used Evan's method to measure the "expanse". I use forewing length all the time as the method was adopted by many researchers.

Teo T P

[atronox]

Just sharing my opinion on this matter:

I would take a few measurements of the forewing length(from apex to thorax) of each wing, then take the average of all readings.

I think this is the most unambiguous way, since the only terms i have to deal with are "apex" and "thorax".

*how does trigo help here? Cosine rule? That means there must be a standard for measuring angles as well :O

[Psyche]

Just sharing my opinion on this matter:

I would take a few measurements of the forewing length(from apex to thorax) of each wing, then take the average of all readings.

I think this is the most unambiguous way, since the only terms i have to deal with are "apex" and "thorax".

:O

Precise defination is the key word in science, Aaron.
That's why it is stated from tip(or apex) to the base of the forewing for FL.

Someone could challenge you to measure a Hawkmoth & which part of the thorax you meant.:bsmile:

TL Seow:cheers:

[Commander]

*how does trigo help here? Cosine rule? That means there must be a standard for measuring angles as well :O

You're our maths wiz kiddo in a special programme! You tell us. :grin2: Somewhere in there, you have a right-angle and forewing length dimension.

[teotp]

I sent Dr. K. Kunte an email asked him about how he measure the wingspan and hopefully he will answer my questions.

Teo T P

Reply from Dr. Krushnamegh Kunte via email: "I will stay in London for the next three months. Please remind me in January 2013."

Teo T P

[atronox]

Precise defination is the key word in science, Aaron.
That's why it is stated from tip(or apex) to the base of the forewing for FL.
TL Seow:cheers:

Yes, i think forewing length should be the international standard to be adopted; least ambiguous.


You're our maths wiz kiddo in a special programme! You tell us. :grin2: Somewhere in there, you have a right-angle and forewing length dimension.

Haha i'm anything but a math whiz.
But i believe it's the angle made between the two forewing lengths.
Anyway, the process seems complicated and unneccessary.