A Question of Letters: On the Enigma of the Brown Argus in Yorkshire


(Letters and replies to Bill Smyllie, the worlds leading expert on the Brown Argus/Northern Brown Argus)


Below: 3 photos of a Brown Argus at Forge Lane, Horbury, West Yorks. 31st May 2004. Stills captured on a memory card from DV footage combined with moving images of railway sidings, passing trains and the M1, for a proposed  film on Butterflies of Industrial Dereliction. (This is probably the farthest north west the butterfly has been recorded). Bill Smyllie noted is "reminiscent" of  var. cramera (the southern European form).

Forge Lane Forge Lane  Forge Lane


Dear Bill,      (Oct 30th 2004 )         


  (I am writing this letter also on behalf of my brother so forgive me if I rather carelessly at times slip between a 'we' and an 'I'). So let's begin! We were intrigued to hear from Susan Stead that you thought the putative 'Brown Argus' photographed in Shipley Station Meadow on Aug 25th 2003 was perhaps after all, a bona fide Brown Argus though insisting you needed more evidence especially specific facts related to the creature's underwings. An uncommonly dark Common Blue female or Brown Argus, it was a very dished specimen and the photos we took are very ambiguous especially those of the undersides which are blurred, shadowy and generally lacking in clarity. Seeing it was so close to expiring I suppose we should have kept it but I find I'm unable to do this reminding me too much of childhood days when collecting was not a problem.

    We would of course liked it to have been a BA but after some indecision we ruefully accepted that Howard Frost, Philip Winter's and Terry Whitaker's verdict to the contrary was correct. As I recall Howard Frost said it was an unusually dark female Common Blue. I then remembered that I had seen and photographed just such a Common Blue on the other side of Bradford at Raw Nook a few years back. Thinking it may have been a Brown Argus after all; I sifted through my piles of photos until I eventually found the photo I was looking for. It was exceptionally dark brown but also there was no doubting it was a Common Blue female. However it prompted me to go in search of other specimens in Raw Nook at the earliest opportunity in the late spring of this year. Though disappointed at finding out they were not the Brown Argus though initially I thought they might be because of the absence of male Common Blues, I then realised I was witnessing a rather unusual phenomena precisely on that account, in that these very few dark females were emerging just prior to the males. A week later and practically all the females were, in one way or another, 'blue' females. This may explain why the butterfly we photographed in the last week of Aug 2003 was so dished whilst the other female common Blues were for the most part liberally suffused with blue and in the first flush of life with barely a scale missing. The qualification is necessary because there were present in the meadow a very small number of very brown females, which was most unusual as the percentage of typical females, had massively declined over the past few years. They were also in excellent condition and likely to have emerged only very recently. On mulling over our observations with Susan she now on reflection had thought all along there was something a trifle strange about their behaviour. Be this as it may if our observations at Raw Nook turn out to be correct and that the emerging times of the unusually dark brown females and the blue females tend to be separated in time then it is an interesting fact in its own right and needs to be investigated. This genetic segregation in time awaits an explanation and I have vague ideas of my own - but that is another story.   

Shipley Underside
(Above. Right: The battered Shipley BA which was a Common Blue.
Left: August 3rd 2003: a real Brown Argus at Dinnington, South Yorks.
The discal spots on the forewings are different)

    Our all too willing suspension of disbelief regarding the butterfly we photographed on Shipley Station meadow is excusable however. Earlier in the year, and literally against all odds, we had in the first few days of August 2003 found the Brown Argus in some numbers at Dinnington and Kiveton Park in South Yorks and, a little later, on the narrow tow path of the Aire/Calder navigation where it runs alongside the still fully operational pit yard of Kellingley Colliery. This was a quite remarkable find in its own right but in our haste to press on to the Gale Common spoil heap we did not want to waste precious minutes taking photos - a decision we will probably regret for ever more! However on arriving at the foothills of Gale Common, we were confronted by a surveillance net that was virtually impossible to penetrate without alerting some interfering goon. For health, safety and, above all, security reasons we were prevented from gaining access to the site. But we also felt this was a shamefaced excuse concealing the real reason: an arresting, unproductive, industrial mountain of sorts, framed with a border of trees against the sky's immensity and rising majestically out of the intensively farmed, tedium of the plain was being furtively destroyed from within, its heart ripped out by giant excavators. And whatever it possessed of scientific value must also perish with it.

     Later that day seated beside a lone bus stop in the nearby village of Cridling Stubbs (a place eerily devoid of people and even the cars that passed seemed strangely empty of occupants like they were ghost driven) my attention was caught by a fading notice pinned to the door of a converted chapel. It read as follows: 'Your attention is drawn in particular to the Town and Country Action Plan where is it (sic) possible that you could help manage and protect habitat and species. The Selby biodiversity action plan (SBAP) is intended to raise awareness associated with a range of habitats and species'- blah, etc, blah etc, blah. The misprint was far nearer the truth because, yes indeed, 'where is it possible''  For all we knew, biocide was taking place just half a mile down the road.

      It had, in all been a very intimidating experience and one we were not prepared for, having frequently scanned the spoil heap with binoculars from Brockadale some three miles to the south and thinking how like the Somerset Poldens it looked from a distance. We really were in for a shock and, even though we had been thoroughly disabused of this fanciful impression last year, we were still unable in 2004 to gain access to this open cast coal site of a truly awesome size whose extent remains craftily hidden from view behind a screen of surrounding heaps kept in place to disguise the scale of the devastation. At some point in the past Gale Common (i.e. the vast Kellingley Colliery spoil heap) has been deliberately landscaped to resemble low hill ranges such as the Poldens or the Mendips. But, alas, not for long. Worse still what glories have perished in this destructive mayhem of digging? This spoil heap also contained an overburden of magnesian limestone as did the spoil heaps on the coastal plain of Co Durham and levelled before anyone thought to make a closer inspection - or rather were put off by E. Durham's industrial image.  For all we know Rock Rose may have taken root on Gale Common and in which case could easily have been a Brockadale overspill with even a colony of Brown Argus. So all we now possess are the enclosed photographs, which, we trust, will verify what we, as raw recruits, witnessed in the summer of 2003.

    Thus throughout 2003 we had honed our skills to such a pitch that we were able to spot a lone Brown Argus amid the more numerous Common Blues even when a fair proportion were typical females as on Kiveton Park spoil heap. Indeed it was the flight of the butterfly in Shipley Station meadow, which initially grabbed our attention. It was different to the other assembled blues that were fluttering about and above all it had that unbroken, silvery browny grey hue without that aureole of telltale blue that characterizes the typical Common Blue female in flight. However it also appeared to be fractionally smaller than even the few typical Common Blue females that in turn were also just that bit smaller than the blue females now showing up on the meadow.

    What to make of all of this? Suffice to say neither of us were put off from continuing to search for the Brown Argus in places they had never been seen before during the hot summer of 2003. In fact we were convinced in spring 2004 we would see them once more in a couple of places in Dinnington, on the Kiveton park spoil heap and on the Kellingley tip in West Yorks situated some three miles north of Brockadale where we had discovered a large Brown Argus colony in 2001. In 2003, we believed we had actually found new colonies of the butterfly in the most unlikely of places and in truth we couldn't believe it ourselves and needed to constantly reassure each other that they were Brown Argus, hour after hour and even day after day. When, finally, the doubts  engulfing us slackened we realised we would have a job convincing others. However we managed to get good views of the underside wings and there was no doubting it. And all of them were invariably in a pristine condition and could not possibly have migrated very far. In 2003 we found several butterflies in two places in Dinnington  roughly a mile apart and separated by a housing estate, and also on the flat area of the Kiveton Park spoil heap some two miles away.  However, puzzlingly, we did not find one in evidently the butterfly's more usual haunt in Anston Stones Wood where their traditional food plant, the Rock Rose, abounds. We say 'evidently' because although we have visited Little Stones and adjacent ridges of the magnesian limestone outcrop merely a few hundred metres away, during the Brown Argus flight period we have never seen a single butterfly despite repeatedly retuning perhaps  13 or 14 times over the past few years!  During August 2003 it was, however, a very brief visit as we fully expected the limestone ridge to be teeming with the Brown Argus because we thought only a massive increase in numbers in a location where it was known to reside from one year to the next could possibly explain why we were discovering so many fledgling 'colonies'.


Big Brown Argus Dinnington Argus  Dinnington Argus
 (Above: Left: First Brown Argus seen in "The Hedges" Dinnington, South Yorks. August 1st 2003. Centre: A perfect imago two day later at nearby Kiveton Colliery. Right:  Distant view of another, two days later on the oldest Dinnington Colliery spoil heap)       

  We didn't visit Lindrick Common, which of course is a far more reliable and consistent BA hotspot, but we guess there probably wasn't a significant increase in Brown Argus numbers during the hot August of 2003. In The Argus for 2003 you remark, in your usual thorough airing of the complexities  that surround the BA and NBA: 'The much larger increase in Brown Argus counts is largely due to immigrants'. Do you mean immigrants from across the North Sea or from neighbouring counties to the south or both? We must admit that the only plausible immigration we could think of was one directly from ex-colliery spoil heaps in North Nottinghamshire although we have no knowledge if there are any permanent BA colonies on these sites. But we certainly couldn't explain the remarkably pristine condition these butterflies were in during early August 2003 suggesting that if there was immigration it must have been from very close by. On the other hand how come on the exceedingly small area of 'The Hedges' (see photos) only one Brown Argus was espied on the 1st of August - admittedly rather late in the day though we are certain we would have immediately seen others - yet three days later numbers had increased to five! We were left with no other alternative than to conclude that the Brown Argus here and in the immediate vicinity must have emerged on these sites, and that suggests singletons (or otherwise) had 'arrived' in either late May or early June 2003 and commenced to breed. I know you think that the situation in South Yorkshire and possibly elsewhere has been complicated by reports of unofficial releases but for the life of us we cannot see who would do such a thing in such unlikely spots as 'The Hedges ' which leads us onto the next point.

  All of this, of course, added to our bewilderment.. We were also puzzled - very puzzled - for another reason. These new 'colonies' appeared to defy nature! Though we searched far and wide we could not locate any wild geranium - no Storks Bill, Meadow Cranesbill, even Herb Robert. We really began to think the unthinkable - that the butterfly having turned to feeding on the wild geranium was now sampling other plants like those belonging to the pea family. But to our lasting regret we had only one camera between us. Worse still we had left the extension tubes and close up attachments in London as we had only decided to bring a camera with us at the last moment thinking we might take some landscape shots of the various pit spoil heaps. Even so the generally poor photos do show it is the Brown Argus. We cursed the fact we had not brought the 120mm Mamiya with us as this fitted with a wide angle lens,  an extension ring, stopped down to f16 and combined with a flash light baffle so as not to distort colour, generally manages to capture a lot of background detail such as buildings, thus leaving one in no doubt as to the actual location. With the benefit of hindsight we should have immediately returned to London, picked up the other cameras then dashed backed north again and taken hundreds of photos. But we were convinced that the 'colonies' we had found we here to stay and we would have plenty of time to make good the omission the following year. But, oh dear, we looked in vain both in the spring and late summer on all the sites we had seen them on last year and did not find one. Obviously too, our gravest error was not to immediately contact you seeing you lived a mere two miles away!

 However there was one notable exception early on in 2004 and one we were not prepared for and which raised our expectations we would find them again in Dinnington and Kiveton. In April of this year we were once more engaged on following up our researches of the previous two years on the Dingy Skipper, wanting in particular to ascertain if it was in West Yorks. We were duly successful finding it on Frickley spoil heap in South Elmsall, new parts of Wooley Colliery, Penistone, Healey Mills Marshalling Yards (the site also of a large Grayling colony) and at Ravensthorpe between Dewsbury and Huddersfield. However because of the cold overcast weather conditions we were unable at Horbury to establish either the perimeter of the colony or make a rough estimate of likely numbers. Nor were we able to say for definite if the Dingy Skipper was to be found in the approach to the marshalling yards in Horbury at a railway siding called Forge Lane and which is close to the Wakefield suburbs. Despite visiting the place on two consecutive days the sky remained overcast. I was about to give up when just after midday the sun unexpectedly broke through. Immediately several male Common Blues commenced to flutter about and almost in exasperation I began to take some footage of them on a camcorder as part of a project I have a mind to do on 'butterflies of industrial dereliction'. But my attention was still directed at finding the Dingy Skipper. But I do remember musing to myself why on earth was that brown 'Common Blue' female assaulting a male Common Blue in a most unladylike fashion? And then in a flash of recognition it came to me. I was beside myself with delight. This was no boring Common Blue; this was a Brown Argus! And fortunately I have the shots to prove it beyond the shadow of a doubt both as stills on a memory stick and on DV video complete with a passing train, views of a signal cabin in the distance, and a shaky zoom shot of lorries hurtling along the MI motorway which crosses the railway line some quarter of a mile down the track. I doubted what I was myself looking at and even thought I must be dreaming but I wanted no one else to be in doubt and fortunately I had the means at hand to prove it. As you can see from the stills it is a pristine specimen and its freshness is even more apparent in the video: it cannot possibly have been more than a few hours old - a day at the very most given the foul weather conditions which would have prevented the butterfly from taking any exercise. Even if the Shipley Station Meadow specimen is a dud and doesn't stand up to scientific scrutiny (which we feel it doesn't) then the Forge Lane specimen must surely be the farthest north west the Brown Argus has ever penetrated?

 I then looked about for likely foodplant finding just one plant of Meadow Cranesbill (obviously not yet in flower) and a plentiful supply of Herb Robert on the railway line but which was some distance away. However where the Brown Argus was flying alongside the male Common Blues there was much Bird's Foot Trefoil and either Hop Trefoil or Black Medick and possibly both. There may even have been a pair of Brown Argus because I noticed another 'brown' specimen close by but unfortunately at that moment black clouds hid the sun and the place went dead.

  I now could kick myself for not going back at the earliest opportunity, weather permitting, to follow the butterfly's movement and to check to see if there were more of them. We did however go back in late August and found nothing, though by this time we were fully expecting not to.

  We were of course delighted at our find but which only added to our disappointment later in the season when we failed to find them anywhere else. But, as so often happens, disappointment turned to wonder once we had taken time out to reflect on this perplexing mystery. It would have been just too simple if the Brown Argus had performed for us. The fact that our expectations were frustrated taught us not to anticipate nature's movements. It was our second reprimand of the season because in August we failed to find the Grayling at Ravensthorpe on a sprawling landfill site surrounded on all sides by railway embankments, similar in some key respects to Healey Mills Marshalling Yards, which was only two or three miles away.  In April, like the hunters of old, we had convinced ourselves it was 'in the bag' ( we could even 'smell' them, we were so certain!) and all we had to do was wait for August to come!

  Looking back we both regard 2003 as a missed opportunity viz. the Brown Argus which may never be repeated. What we actually witnessed must have been related to the unusually hot summer and no one in their right minds would want such summers to become commonplace. It had overtones of an apocalypse and I well recall at the moment the temperature hit 100 degrees in London, venturing out into the baking, deserted streets to order a book on the Permian extinction 'When Life Nearly Died'. In this book it is claimed, on convincing evidence, the mean temperature rose by a mere 10 degrees that, alarmingly, is within the forecast predicted by the IGCC (Inter- Governmental Panel on Climate Change) as likely to be the case in a 100 years from now. Even so I wish we had been less blase and had been quicker to appreciate we were witnessing something unusual and that may well be, for the Brown Argus, a one-off. At the very least it called for an exhaustive photographic record. And patient observation (mating and particularly egg laying/choice of foodplant) may well have provided fascinating, and even lone, not to be repeated insights this side of oblivion. For, to be honest, I know of no other British butterfly that behaves in such a baffling way and which at present mocks all explanation.

   It seems the Brown Argus undergoes inexplicable crashes with one colony thriving whilst another is decimated. Could we be looking at a variant of this pattern, one that is particularly unusual because the butterfly is turning up in spots like in W Yorks where it has never previously been recorded' Although we cannot say for certain we believe if we'd had time in early August 2003 to investigate Maltby, Thurcroft, Waleswood, Edlington and Orgreave spoil heaps etc we would have found the butterfly there in small numbers as we did at Dinnington, Kiveton and beside Kellingley Colliery This sudden appearance and then equally dramatic disappearance may explain why the thought crossed all our minds that someone was introducing the butterfly by the basketful. Re-reading my 'Nature Notes' I came across the following entry for May 24th 2002 (Brockadale): 'The Brown Argus is literally to be found all over the nature reserve and outside it. This must mean the colony has been here for some time ' at least 10 years I would guess. 200 adults would be a conservative estimate. I would put it at over 350 possibly covering more areas than we yet realise.    

   As a result of our experiences in 2003 it now occurs to us the BA colony at Brockadale might be of recent origin. I only wish we had visited the colony in Aug 2003 to see if there had been a similar extension in its range onto outlying fields around the Brockadale reserve where Storks Bill if not Rock Rose can be found. However the count for Brockadale last year - 2003 - was surprisingly low (see The Argus).

    We shall however continue to keep a look out for the butterfly in the Bradford area. We did notice in July this year when following the progress of the Ringlet in to the vicinity of Shipley Station Meadow that on the railway line to Leeds there was plenty of Herb Robert. Moreover beside the railway embankments in the uncut meadows that sloped down to the Aire and Leeds Liverpool canal, patches of Meadow Cranesbill could be seen. If it was indeed a Brown Argus in the photograph we did wonder if the butterfly had not originally come from here and then found its way into Shipley Station meadow only a short distance away? On last years reckoning it would have been an ideal spot to look for the butterfly and we have every intention of taking a further look next year.

 We have included photos of what we thought might well be a gynandromorph ab: albianunalata of the Brown Argus. We took the photo on top of the magnesian limestone cliff in Brockadale and a hair-raising experience it was at time! The following notes were made that evening and are reproduced verbatim.

                      'We may even have photographed a great rarity...  

  I was first aware there was something unusual when from a distance of three feet noticed that only one of the upper wings carried the white discal spot. On peering through my 21mm extension ring I saw there was one, after all on the left upper wing but it was fainter and less pronounced. After taking a number of photos it flew off landing on a grass stalk, closing its wing though not enough for the right side to completely cover the left. It appeared to be somewhat deformed and though both David and I noted it neither of us commented on it. Eventually it opened its wigs fully flattening them out to soak up the sun. I noticed the bottom left wing was smaller than the right. And then in a flash it came to me: 'It's a gynandromorph' I cried out.

  We must have taken some 40 photos between us so let's hope some come out. We debated whether to capture it but decided not to. The scientific community would argue that in the circumstances it is right to kill it. And maybe because we weren't prepared to, our claim will be dismissed. But if I had done so I personally would have died a little inside. Besides what more could a dead insect have proved: that anatomically (thorax, genitalia etc) it was an 'hermaphroditic' sexual mosaic? But supposing that anatomically it was single sex either completely male or female, does that necessarily discount that it is a gynandromorph' Though a gynandromorph must have the XY chromosome does it have to do so in equal measure' Indeed is this ever possible? Is not the difference in wing shape, size or markings sufficient?

  Gynandromorhism cannot be common amongst butterflies. If so there would be photos of sexually dimorphic species such as the Brimstone, Purple and Brown Hairstreaks and so on. In fact I don't know of one. That we were fortunate enough to notice it came about because we were looking for the white discal spot. Otherwise we would have completely overlooked it.

  We also have included some paragraphs from other incomplete 'works in progress' which came to nothing because of an over-ambitious intention to study the magnesian limestone strip in more detail. After studying the geology maps we realised we had spent an important part of our lives right on top of the strip and which well may have stimulated our already awakened interest in butterflies and moths. As you know the magnesian limestone band runs from Nottingham through Bolsover alongside the M1 to Bolsover then to Anston Stones, Brockadale, Boston Spa, Knaresborough, Makershaw (Fountains Abbey) up to Darlington where it gradually widens out into a wedge forming the steep cliffs of E Durham and terminating at Cullercoats just down the coast from Whitley Bay in Northumberland.

  Perhaps to end this long letter, the following notes may be useful. They are from a proposed pamphlet which was never completed and provisionally titled: 'Brockadale: A Brown Argus colony and a possible gynandromorph plus some thoughts on conservation (buildings/flora/fauna)'  

 For what it's worth we also noticed the normal agestis form and the ab. albianunalata variation tended to prefer different locations. Curiously the insects with pronounced white scaling preferred the slightly higher ground whilst the typical form was most in evidence on the river Went flood plain and the lower slopes. However both tended to shun the upper reaches of the steep grassed bank sides. What conclusion one can draw from this is anybody's guess. Maybe the scaling is a sex-linked characteristic, the males seeking the higher ground from which vantage point it is easier to see the females on the lower ground.

  On noting the white scaling in the late summer of 2001 we excitedly jumped to the conclusion we had stumbled upon the second generation of a Northern Brown Argus colony. A few years back on August 26 1996 we had snapped a singleton NBA on near vertical scree high on Arnside Knott. This was clear proof that suitable microclimates like that of Morecambe Bay could nourish a second generation. But now we could only shake our heads in disbelief as the nearest NBA colonies lay 50 or so miles to the north (Ellerburn Bank) and west (Skirethornes in upper Wharfedale). With some trepidation we immediately referred these discoveries to the world's leading expert on the Northern Brown Argus/ Brown Argus, Bill Smyllie.


NBA NBA Gynandromph

(Above. Right: Second generation Northern Brown Argus at Arnside Knott, Morecambe Bay. 26 August 1996. Centre: Underside of same. Right: The possible Brown Argus gynandromorph at Brockadale which Bill Smyllie probably rightly disputes)            

 The picture book part of this pamphlet is taken up almost entirely with photos of an aberrant ab. albianunalata - an ab. of an ab; a rarity amongst rarities. And even if these superlatives appear exaggerated, one must admit it is most unusual. In fact half way through harassing this insect for more photos, even pursuing it over the headland of the scarp, a thought suddenly struck us. Could it be a gynandromorph? We had noted there was a lack of symmetry between the right and left side on both upper and lower wings. And when the butterfly closed its wings there was a pronounced border where the left side did not completely conceal the right. Sometimes, of course, a border or fringe becomes intermittently visible when butterflies at rest begin to rub their wings together for brief intervals. It is not at all uncommon, and for a time the usually more cryptic concealing qualities of the underwings no longer do their job properly. This however was different: it was a permanent feature.

   Had we not been looking for the elusive white scaling, which was surprisingly nearly absent in the second generation, we would not have noticed how peculiar this insect was. In fact the first thing we noticed was the mismatch in scaling between the right and left upper wings: the rest followed in due course. However, the more explicit the difference between the male and female phenotype, the more impressive the gynandromorph. Equally, where the male and female are practically identical, a gynandromorph is pretty much bound to pass unnoticed. For instance, how many agestis gynandromorphs have been overlooked because of an understandable failure to note that the, in any case hard to see, discal spot is missing from one of the upper wings? This would have been true, in this instance, if our eyes had not been peeled to look for the white scaling. Interestingly the 'description of imago' entry in the Heath/Emmett Butterflies of Britain and Ireland says in the females the apex of the upper wing and outer margin (termen) are more rounded (i.e. the right side in the photos), whilst in the male the apex is 'rather acute' (i.e. the left side in the photos). Look carefully at the photos and the difference is obvious. However the same entry insists there is no observable difference in form between the female and male underwings ' which is patently not the case here. Yet picking up Edmund Sanders book on butterflies (1939) and the difference between male and female underwings for his Brown Argus illustrations is at once apparent, with a much more acute inner margin on the male than on the female. This does not quite correspond to what can be seen in the photographs where the left underwing outer margin (termen) is more acute than more rounded right underwing outer margin (termen).

  Gynandromorphs are sexual mosaics, the result of a chromosomal irregularity. Though a sex intergrade it is wrong to call them hermaphrodites because they are sterile. They are neither male nor female and rather are an amalgam of male and female characters that develop simultaneously. For some reason they are restricted to the order of insecta. Naturally we ardently want to believe the insect we photographed on August 23, 2003 was a first.  But to be absolutely sure we would have had to kill the insect and examined the body for other signs like composite genitalia. But that we couldn't do. We also think it was not an intersex because the difference in wing structure between the right and the left-hand side would have been less pronounced. An intersex develops first as one sex then changes into another, hence the organs that are the last to develop, like wings, are the least affected.


Anyway we hope the detours are not too labyrinthine and that you find some of the above interesting.

All the Best

Stuart (& David) Wise


Bill Smyllie's reply:

November 2nd 2004

Dear Stuart,

    Very many thanks for your long letter and several photographs which I received safely. I think that it will be best to comment under several different headings with the rider that if you feel that some of your questions are not answered you can feel free to ask again.

   First the situation at Shipley station both with the possible Brown Argus and also Common Blue. I looked at the upper side photo, which Susan showed me and concentrated on the hindwing lunules. At the time I inclined to Brown Argus because the white line under the black bottom portion of the lunules was more or less a straight line. In the average Common Blue female it is a white area surrounding a more or less circular black patch. However, with the help of your undersides there is no doubt now that it is a common Blue. I have seen many more undersides of Brown Argus than Common Blues, but I have not come across any Brown Argus with one or more ocelli inside the largish forewing 'discal spot' mark.

    Regarding Common Blue at Shipley station, I have chatted to Susan from time to time at Yorks. BC AGMs, but have never been there, so all my comments are second-hand. Please find enclosed a copy of my most recent paper. On p172, point 7, the Common Blue gets a mention. Provided Susan's recent comments turn out to be correct, brown females emerge first to be followed by others which tend to become more blue through the flight period. I know from the Brown Argus that nothing is ever precise, but if the above is generally true then it will mean that at Shipley station there are morphological differences in the Common Blue. In the next issue of The Argus I have a paper in which I propose that most species have northern and southern components in Yorkshire which over time have hybridised, just like the Brown Argus, and this shows as a long brood period (7 to 11 weeks) with a peak in the middle of the flight period. If there was no hybridisation there would be two separate peaks. Also, if there was no such occurrence the flight period would be much shorter. What the Brown Argus has done is to show a more general mechanism through its morphology. Over a period of time, including the last ice-age there has been overlapping of say bivoltine and univoltine portions. In my 1997 paper an analysis of the ratio of the black centre to the rest of one particular occelus in both Common Blue and Brown argus shows that the histogram of increasing black centres between the minimum and maximum approximates to a sine curve. The actual Common Blue figures, estimated to the nearest 5% (diameter of pupil to diameter of ocellus) for 98 specimens from different parts of England are: 35% 2; 40% 2; 45% 7; 50% 18; 55% 30; 60% 30; 65% 8; 70% 1. Brown Argus figures show a similar pattern, so does the Xerces Blue in the States where, just as in the UK, the black pupils increase in diameter as one goes further away from either the Scottish border or San Francisco. It is possible that the position of a peak with respect to the beginning and end of the flight period will give an indication of the proportions of quicker and slower developing individuals. Since inclement weather will truncate part of any brood with, in my opinion, an alteration in the total genetic bank, I think it would be very difficult to get any positive information on this one.

      I am sorry to disagree with you about the possibility of your gynandromorph. In all I estimate that I have looked at some 2,500 Brown Argus males and 1,000 females. Both upperwings in your specimen have lunulation which is more consistent than, but above all larger than that of any males I have seen. Regarding the white discal scales there does seem to be quite a difference between the two, but it is normal for there to be some difference between each wing, particularly when smaller numbers are counted ' larger numbers have been too complex for me to bother. The left hindwing is not fully developed: the left forewing may be slightly different in shape to its partner, but broadly speaking it has a rounded female shape. The average male is slightly more angular. Having said that, you have a female from Dinnington which is less rounded and a male from Kiveton Park which is more rounded than normal and which is as well lunulated as most males I have seen. The maximum lunulation would be only very slightly larger and consistent in colour over the 6 lunules.

     Some comments on variation on both lunulation and white discal scales: please forgive any repitation from a year or two back. First of all, male lunulation drifts down as any flight period of a brood progresses. You will see from the paper that it has been possible to differentiate from early and late in an agestis  brood at Magadelen Hill Down (MHD). The proportion of 4mufl has risen with the occasional 3 mufl. However there are some 5 and 6mufl around. The converse is broadly true with white discal scales. I have copied out my data on the proportion of specimens with no discal scales from various colonies:

 males 0%                            
 females 0%
 males 42.7% from 103        
 females 17% from 53
N Lancs:                               
 males 32.2% from 121       
 females 17% from 53
Peak District                         
 males 63.3% from  49        
 females 32.1% from 28
C England:                           
 males 61.7% from 193       
 females  36.3% from 113
C England:                           
 males 70. 1% from 147       
 females 35.9% from 103

C England ' Thames to Humber: S England - south of Thames and Bristol Channel

European agestis
 males 97.8% from 45          
 females 97.9% from 48
European allous                    
 males 95% from 60             
 females 85.7% from 35

      These are overall figures which smooth out the irregularities from any one brood. It is possible to get a well lunulated female (less commonly a male) which also shows albiannulata. Broadly speaking, later emergence will contain more white discal scales. You will notice that continental agestis and allous have very low numbers. This is certainly the case in France ' in Scandinavia there can be moderate numbers of white discal scales. Among other things this means that the Channel had formed after the last ice-age before any artexerxes white scales had reached the south coast. They did eventually because the occasional white spot can occur anywhere in England and you can see that c1 male in 3 and 2 females in 3 will have some white scales down in S England.

    Immigration - you will have already gathered that I am not talking about Brown Argus having crossed any of our local seas, I am referring to the northward migration of Brown Argus from N Norfolk since 1992. This year records are coming in from the vicinity of Harrogate and I believe also Scarborough although this is merely word of mouth so far. Taking Scarborough as a measure, the migration has covered c120 km in 12 years, i.e. it is at the rate of c10km pa. I do hope that you will continue to cover the ground as you have been doing recently, because I am sure that there is more to be found out about the Brown Argus. It seems to me perfectly logical that not all sightings will result in continued occupation. This does seem to have been the case at Lindrick although I have not checked the position this year. I have in fact been looking at Coombs Dale and Cressbrook Dale because of the poor lunulation figures shown in the Aagaard et al genetic analysis paper. The results indicate that the Coombs Dale male figure in Aagaard can be explained by a sampling date later on in the flight period (identical to the MHD figures). The Cressbrook Dale figures are distinctly lower and I conclude that there has been an unauthorised introduction here. This makes life more tricky al round, and the large numbers suddenly appearing at Brockadale make introduction a probability. Having mentioned these two I am inclined to think that others are genuine migration. The migrating species will I believe belong to that part of any colony which possesses the most southern characteristics, i.e. that part which emerges first. It follows that it will be well lunulated and will have a lower white discal scale content than average. So there is no positive evidence that any of the mainly univolotine colonies like the Peak district or the Yorkshire Wolds have reached the stage of migration. Re foodplants, as one goes further south so the range of plants expands. I came across an example of Brown Argus migrating southwards towards the Alps along the Neckar valley south of Stuttgart. The foodplant there was Meadow Cranesbill. I guess that both it and Herb Robert might be possibles, also Doves Foot and Cut Leaved Caranesbill which can be not all that obvious because the plants can be quite small. As more data becomes available it seems very likely that there can be variation from year to year in the lunulation content of agestis colonies in addition to the variation between early  and late in any brood. You will see from Table 6 that this is so at Pickering. Although I suggest that it should be called agestis because of the lack of Omufl, it will vary more than the better lunulated agestis colonies. It does however make sense to expect some variation in agestis colonies further south but I do not have enough data, and doubt if I will try to collect any.

    Your excellent photo of a female at Horbury on 31. 5.2004 merits some comment. The female lunulation is towards the upper limit of what I have seen and is reminiscent of cramera. I am trying hard to organise some more genetic analysis from a small number of males early and late in flight period from an agestis colony, but it is not proving easy. If people had confidence in lunulation counts they could get information just by looking at specimens. Also if some tests were made on cramera I believe that there would be a component in our agestis and also to a lesser extent in the Durham colonies. This good lunulation makes sense in terms of the best lunulated males and females being the most likely ones to migrate. With 2 females and 1 male in the relatively small numbers which you have sent me this seems to confirm either the migration or the progeny early on from a migration.

                                                                                                   Best Wishes,

                                                                                                      Bill Smyllie