Wednesday 9 September 2015

Butterbur

Had a few Rosy Rustics in August in my Robinson trap as I do most years, but last night I was chuffed to trap my first ever Butterbur in my garden in Sonning. I was able to confirm this by prising open the wings to reveal dark underwings - although it refused to stay like that for photos! In my edition of Mapmate there are only two records for BBO and nothing since 1998 it seems, so I am guessing this is fairly unusual, but happy to stand corrected.

3 comments:

  1. Hi Alistair,

    I'm pretty sure the moth in your picture is Rosy Rustic I'm afraid. Butterbur is much plainer, darker brown in colour, less boldly marked and as you suggest not at all common round these parts. You have to trap right in among the food plant where there are substantial stands of it. I suspect that the mapmate records are limited to those who use it, but I don;t know as I don't use it but I know of several records since 1998 in BBO including one I caught in Benson 3 years ago and I believe it is caught at Thatcham. I think your Rosy Rustic might be a male which has darker hindwings than the female. Butterbur would be a fantastic and very unlikely garden record unless you have the Butterbur plant in your garden. BW, Marc

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  2. Hi Marc, I just need to check before settling on the id - this was a very large moth - the size of the good sized Large Yellow Underwings in the trap with it and the underwings were very dark. I have had both large and small specimens of Rosy Rustic before, but never any this big nor with such a dark underwing. Having said that, there is as you suggest no Butterbur in my garden nor probably within a mile or so and the wing shape doesn't look quite right. Knowing all this, what do you think?

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  3. Hi again,
    I have had plenty of very large Rosy Rustics and in fact checked a rather large one this morning and it had dark-ish underwings. Butterbur is not necessarily that much bigger, the size ranges overlap, but it is broader and the markings are ill defined - it's like a darker brown ugly Rosy Rustic. Your's is very golden brown and very well marked and as you suggest doesn't have the right shape. I personally would have no doubt that it is Rosy Rustic, but others may have alternative opinions. I think Butterbur is one of those moths that once you see one you realise you've never seen one before for definite but just going by the books there's always some doubt up until then. I have trapped dozens of times in large patches of Butterbur plant and only ever caught one so I am not highly experienced with seeing this moth, but it was very obviously different from Rosy Rustic. If you have the specimen you can get it chopped to double check. I think the fact there is no foodplant anywhere nearby probably is sufficient further evidence but moths move about otherwise they'd never find the next batch of foodplant and things turn up in weird places - in fact I believe that for some species you can be more likely to catch the dispersing individuals away from their breeding areas - Striped Lychnis rarely turns up at light on sites where there are colonies (in my limited experiences and others I've heard of) but I have caught several nowhere near any foodplant.

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