www.ukbutterflies.co.uk

As I've mentioned elsewhere (I think!), I'm writing some content for UKB on the subject of variation. One aspect is sexual dimorphism (differences in appearance between male and female adult butterflies). I want to distinguish between species using a spectrum showing the extent of sexual dimorphism and have come up with the figure below. I'd be interested in any disagreements!

Cheers,

- Pete

Hi Pete,

From my experience, it's easy to sex a Speckled Wood, perhaps deeming it a 'subtle' difference.

Cheers

Lee

It's difficult, as it is quite subjective and depends upon how well you know a particular species. Ringlets were a particular fave of mine for a few years and it got to the stage where I could confidently sex them in flight from a good distance. To me the sexes were quite different.

So how about a general rule of thumb method of separation...?

Insignificant - Careful examination of specimen required, looking for specific determining characteristics.
Subtle - Cursory examination of a pitched specimen can determine sex, possibly in flight with experience (so I agree with Lee here with the Speckled Wood).
Noticeable - Simple to determine sex, even in flight.
Significant - Sexes so different they could be mistaken for a different species.

Felix.

Excellent input! Ta very muchly. Definitely subjective!

Cheers,

- Pete

I have been told that Swallowtails can be sexed by subtle differences in a black mark near the apex of the forewings, the female spot being entirely surrounded by the background yellow whereas in the male this equivalent spots smudges into the nearby black. So if true, then maybe Swallowtails should be in the subtle category.

And I agree that when new, Ringlets are very easy to sex, the female being paler.

Jack

I've nearly concluded the article - but need help with the following - and thx!

Is anyone aware of variation in eggs? (I have examples of larvae and pupae)

Is there an example of mimicry in British (or, failing that, European) species?

The Map exhibits an extreme form of seasonal variation - what advantage does this provide to the adult butterfly?

Cheers,

- Pete

I'm not aware of any true mimetic relationships between European butterflies, though the monarch obviously has Müllerian and Batesian relations in other parts of its range (the viceroy has recently been claimed as a Müllerian mimic, contrary to what we all learned at school, since it is at least as noxious itself as the monarch! Felix will groan to learn I got that information from Wikipedia ( ) when I was explaining mimicry to some students recently, but the Wikipedia article does link to Nature: http://www.nature.com/nature/journal/v3 ... 497a0.html).

I didn't catch this thread when it first appeared, but if I had I would have pointed out that there is considerable sexual dimorphism in Scotch argus on the underside...

Guy

padfield wrote:I got that information from Wikipedia ( )

Uuuugh, Wikipedia! That's an appropriate source for citation

Felix.

Hi Pete,

If I remember rightly, there's a discussion of mimicry among adults of the British Pieridae in Roger Dennis' Ecology of Butterflies in Britain and Ireland. The Large, Small and Green-veined White formed a Mullerian mimicry ring, and the (female?) Brimstone was a Batesian mimic of these - at least that is my very vague recollection.

Just my observations, but I would have classified the difference between the sexes for Brown Argus (Aricia agestis) as more than Insignificant, perhaps Subtle on this classification, based on the extent of the upf orange marginal lunules. I have not seen the UK version of Mountain Argus (Aricia artaxerxes), but the Alpine version shows this clear distinction, usually to a much greater extent than agestis.

I would also have thought that the sexes of Black-veined White (Aporia crataegi) were very similar, on this classification maybe Subtle rather than Noticeable.

Roger

Hi Pete

Just some observations made whilst preparing my DVD from this years exploits and comments made by others out in the field as follows:

Green Hairstreak: Males appear to have significantly more white fleck marks especially on the hindwing when compared to females although this varies quite a bit. Very subtle though.

Scotch Argus: The female is certainly paler than the male like milk chocolate compared to dark chocolate and the underneath of the hindwing appears very different in the sexes. Subtle or maybe noticeable.

Small Heath: Comments made that the female has an indentation in the lower edge of the hindwing that does not show in the male. Very subtle.

Speckled Wood: Females appear to have larger pale areas around the eye spots and from observing my video closely the males seem to have an area of rough cells on the upper forewing possibly a sex brand of sorts. Again quite subtle.

I agree with Jack on the Swallowtail I think we chatted about this at Strumpshaw. The spot on the male sometimes fills the entire cell obscuring it. When present though the spot on the male is in a different cell to the spot on the female (I think), maybe corrected on this. Again pretty subtle.

Interesting subject and should promote plenty of discussion.

Cheers Paul

Paul:

I agree with Jack on the Swallowtail I think we chatted about this at Strumpshaw.

You are quite right Paul. I was only quoting what you told me (although in have to admit I'd forgotten who it was who mentioned it).

Jack

My only Swallowtail picture from a few years ago, with a clearly visible spot - male or female?

Until now, I had no idea there was a difference!

Dave

Hi Dave

The spot on your picture appears to be only on one wing and not at the tip of the wing as in Jacks pictures. However, from what I have seen in the field and from other photos as there is no spot at all near the wing tip this would suggest a male.

Paul

Sorry I forgot to ask was this photo taken in Britain or abroad as all the images suggesting the spots may give reference to the sex I have looked at were of the British race.

Cheers

Paul

It's britannicus and, as Paul suggests, a male.
Neil

I noticed the same spots in the European race in Spain and saw both male and female Swallowtails. I must admit I wouldn't have noticed if it wasn't for this thread though.

Cheers

Lee

Hi Dave

One final comment. It's a great shot showing a good amount of out of focus background.

Paul

Thanks to everyone - I shall note its maleness for future reference.

For the record, it was taken at Hickling Broad back in June 2004 on a now rather out-of-date Sony P-10 camera, using the meagre 3x optical zoom. But I like the shot too (Thanks for the kind comment, Paul!). A return trip to the broads is long overdue.