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I only got this top shot of a fritillary flying in shady conditions near the lane in Trentishoe Combe, Heddon Valley on 24th July. The National Trust walks leaflet said the area was favoured by high brown, whereas the dark green preferred the open bracken slopes above. There seems to be a slight inwards curve on the lower edge of the upper wing, but perhaps I'm imagining it
Are there any other diagnostic features I could look for? I've noticed that the 'hem-like' band at the edge of the inner wings looks more compressed on many dark green fritillary pictures, but I don't know if this is significant.

Any opinions much appreciated

James

i agree about the inward curve in the edge of the forewing and, more significantly, the small spot, after the first two spots from the apex is indented. These make me pretty certain that it's a High Brown.

Mike

Are there any other diagnostic features I could look for?

The undersides of HBF and DGF are distinctly different and this is the clearest way of separating the two. I'm no ID expert but I'd go with Mike with High Brown.

Kevin

Thanks, Mike and Kevin,

It's great to think I've (most probably) seen my first ever high brown fritillary. I was beginning to think they'd be my butterfly nemesis. If there's a next time, I'll try harder to see the underwings!

James

I’m no expert on UK HBF as, although I see plenty in France, I have never managed to see one in England.

As Kevin says, even a glimpse of the underside would be definitive.

Assuming this is your only photo, I would suggest these pointers:
1. the submarginal marks (i.e. the crescent-shaped marks just inside the edge) on the hindwing tend to be solid for DGF and thinner and more clearly arc-shaped in HBF. This very strongly points to yours being HBF.

2. the concavity of the forewing. Not always entirely convincing and it seems this is rather more pronounced in the male. But if it is slightly concave, it is HBF.

3. most significantly, for male HBF (and I don’t think from the length of the abdomen and the shape of the end of the abdomen – not entirely clear here – that this one is a male), the forewing veins 2 and 3 (the male sex brands) are noticeably thick on HBF and not on DGF. This isn’t the case for the female, of course, so doesn’t apply here.

There are various web sites where you can test these differences (always assuming that they were correctly identified).
Roger

Apart from physical characteristics, when you have experienced both in flight, there is a big difference in jizz. DGF has a noticeably higher wing beat rate and when it lands, it often lands in the shade at the base of a plant.
Christopher

...it often lands in the shade at the base of a plant.

Surely this is mainly females looking for egg laying sites? But I agree, the general jizz is quite different.

Tony M.

Thanks, guys, for all the great tips,

James