White-letter Hairstreak (Satyrium w-album)
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2017 photographs highlighted in yellow. Click on any photograph to go to an enlarged picture, or simply scroll down the page.
This is less common than its Satyrium cousins and superficially quite similar, although the "W" shape of the white band of the unh both gives it its name and leaves no room for doubt. It also seems to have longer tails than the others, and the female seems to have longer tails than the male. The marginal marks are otherwise quite similar to the Sloe Hairstreak (S. acaciae).
There appears to be a reliable way of differentiating the sexes: in the cell area of the unf there is a mark which is very slightly raised in the female and rather more so in the male. This is in addition to the clue given by the length of the tails.
There are varying amounts of blue scales on the black unh
marginal mark in s1. Ironically, it occurs in the UK whereas the other Satyrium species do not (apart from the
Black Hairstreak (S. pruni) which may be threatened
with extinction). It is possibly one of the few butterflies that is actually
more common in the UK than France.
An intriguing insight into the ecology of w-album by Liz Goodyear and Andrew Middleton is on YouTube: https://www.youtube.com/watch?v=rTqPQj6xZtQ
|40694||M||a male, based on the shortness of the tails and the raised area of the unf cell.||200|
I'm guessing that 6242 is a female based only on the length of the tails, as there are virtually no other clues if the body shape is not visible.
I suspect that this is also a female, based on the tail length, the visible body shape and the size - I recall that it was exceptionally large. However, I did see it on 15 May, very very early for any Satyrium species, and the early emergence would tend to argue for it being a male.
|33690||F||not quite square-on, so the colour looks a little greyish, but the white markings show up nicely.||680|
|40689||F?||I'm not entirely convinced that this is a female, as the unf cell area is rather ambiguous, and the tails are rather short. The abdomen appears quite wide, but maybe this is within the normal range for a male c.f. 41650.||200|
|41650||F||clearly a female based on the length of the tails and the width of the abdomen.||180|
|41665||F||a female based on the length of the tails.||180|