Small Blue or not Small Blue?

When you’re learning about butterflies and identifying them, and you’ve made one or two howlers in the past, you tend to be a little cautious about flat out, definite identifications. Particularly when the individual butterfly in question is worn around the edges and even more so if you see it at a time when the species in question is not supposed to be about.

According to the UK Butterfly Conservation website, the second Generation of Small Blues normally appear in the third of fourth week of August. I saw this particular butterfly (above) on August 2nd – last Sunday at Tilshead Down – and its tatty condition suggested that it had been around for a good week or more before that. I decided it was extremely unlikely to have been a left-over from the first generation which would normally have petered out by the end June. So if this particular butterfly was a Small Blue and part of the second generation, it had been around getting on for a month before Small Blues were supposed to start emerging.

But looking at the pictures, I can’t see what else it could be.

The following day, I saw the first of the second generation of Common Blues that I’ve seen this year in the area where I normally walk the dogs – I’d been keeping an eye out for them for a week or two. I only saw a couple of them on the two or three mile walk – one male, one female. When they’re in full flow you’ll see dozens in that area. So it looked like the emergence was only just beginning. And the appearance of these two individuals suggested that they may well have only broken out from their respective chrysalises hours before.

Do the clearly visible markings showing through from the underwing suggest that the wings haven’t dried out fully yet, the butterfly having only recently emerged?
Wings looking strikingly fresh on this female Common Blue. And it looks like the forewing on this side is crumpled. Maybe, still stretching out/unfolding from the confines of the chrysalis? (She’s also wearing very smart stripy socks that I haven’t noticed before.)

This was on August 3rd, and the Butterfly Conservation Website suggests that Common Blues (second generation) normally start to emerge in mid July.

So you’ve got a Small Blue appearing getting on for a month earlier than you’d expect it to. And Common Blues appearing maybe a couple of weeks after you’d expect – in a typical year. So no particular pattern. And of course these were isolated, local sightings of no statistical significance, but it did get me wondering about what it might be that affects the timing of the emergence of these different species of butterfly. 

How much of it is down to the weather leading up to their emergence – perhaps affecting the prevalence of their food plants? Can the inhabitants of chrysalises time their emergence to make the most of conditions? And if so, how on earth would they do that?

With the Small Blue I didn’t see any other Small Blues about, so perhaps it was just a mutational aberration. In which case this individual wouldn’t have got to pass on its genes to the next generation. Maybe, when it comes to emerging from your chrysalis, as is the case with many other areas of life, timing is everything. But then again maybe there were plenty of other Small Blues about that I just didn’t get to see, and they were all just ahead of the crowd, having their only little exclusive party.

Tilshead Down. Picture taken a couple of weeks ago. The ‘X’ marks the spot where I saw the Small Blue two weeks later – and a month earlier than expected.

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2 Comments

  1. Yes, I’d say it was a Small Blue. It’s hard to see the markings on the lower underwing, but my Swiss book suggests that there is often a blurred black marking towards the edge of that wing, which yours has. The size usually gives them away too as they are tiny. As for the Common Blue, I took a similar picture (on the 30th July) with the spots showing through to the upperside, but for some reason I didn’t include it in my selection. Interesting questions though (to which I don’t have any answers I’m afraid). The next time I see my expert (the author of my Swiss book) I’ll have to ask him.

    Liked by 1 person

    1. I also noticed there are pale rings around the black dots on the underwing – they’re more dots than dashes – which I think is a Small Blue identifying feature as well. So it’s unanimous! If you do get to talk to your expert would be very interested to hear any thoughts on questions raised. What fascinating creatures they are!

      Liked by 1 person

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