Following Dave's challenge and checking back to my Waring & Townsend I find that the distinction between these two species isn't as clear as I thought. It seems that there are a few Common Wainscots that have grey hindwings and this is more common late in the season. This was an obliging example from this morning. Is this a Common Wainscot? How do you distinguish them ?
What should I be looking for in the normal Smoky Wainscot season to distinguish them? I've included two pictures from this morning and some photos of my "voucher specimen" taken July 2014.
From July 2014
Mark Griffiths, Garsington, Oxford.
Hi Mark, a couple of years ago, faced with the same question I briefly anaesthetised several potential Smoky's in late August, similar to yours above, and found that several had greyish underwings (topside) but that none had 'substantial' blackish streaks/suffusion on the underside of the forewings. While this is subjective it does agree with the illustration in the WTL guide showing that Smoky should have a good amount of blackish marking across the forewing underside (i.e. in agreement with comments made by the CMR on my own records, the occasional black streak on this part of the wing is not sufficient to make a Smoky designation) - and I now advise those submitting records to iRecord that the forewing underside is a more relevant part to look at in making a decision. However, as you note, while the illustration of Common Wainscot in the WTL guide might be thought as slightly misleading showing no greyish suffusion, the text of this guide is quite clear in noting that its hindwing is less commonly extensively grey and examples like this "may also have extensive blackish streaks on the underside of the forewing". There is therefore perhaps a grey area (not a pun!) where it may not be possible to decide on some specimens at this time of the year (ignoring other criteria such as wing shape, etc.). It would be interesting to hear the opinion of more experienced observers on this difficulty.
ReplyDeletesigh, long reply went into the ether. Any way thanks John. They have a brownish stripe underneath, no black I've seen. I'll remove my September records and look at the two species during the main flight period to see the differences.
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