Another puzzler.

Another interesting moth for people to look at from last night here at IGC, I know what I think it is. See what you think!

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9 Responses to Another puzzler.

  1. Brian says:

    I’d say – Small Rivulet, (2 equal indentations on the white cross band which has a fainter dark line through it than Rivulet).

  2. Paul Kitchener says:

    I must say I’m struggling to see a reason why it’s not a Small Rivulet. The thin, whitish cross-band before the middle of the wing is quite prominent, other than that I can’t see anything unusual. I give up Neil!

  3. Neil says:

    It is Small rivulet guys. Unusual as I think it is incredibly early – my previous earliest record is right at the end of June. I normally only see Rivulet at this time of year, and this moth was the same size as a Rivulet in the trap.
    Going on how late the season seems to be running surprising to see something ahead of schedule!

  4. Raymond Watson says:

    OK so I am going to be the problem person because I say it is a Rivulet. Why? Firstly size and timing. Secondly the double projection from the central band into the postmedial line is NOT a good separation of the two. Thirdly the subterminal line at the apical end is of the correct shape for Rivulet. Finally the subbasal line has even thickness for the two white edges for Small Rivulet and has a thinner proximal thickness and especially on the dorsum a thicker distal thickness in the Rivulet. The Small Rivulet has its lines and bands displayed more evenly and regularly than the Rivulet.
    Tell me why you think I am wrong.

    • Paul Kitchener says:

      I’ve no idea if you are wrong Raymond, but I’ve also no idea if you are right. I can see all the features that you mention but whether they hold true for one species and not the other is difficult to say unless you’ve dissected a sample of a population.
      As for flight period, I’ve recorded Small Rivulet in May (earliest, 8th) in three years out of twenty – but perhaps I got the ID wrong. Neil does say it was the same size as a Rivulet in the same catch which, undoubtedly, is odd.

    • Neil says:

      See, told you the moth was interesting! This is what this blog is all about, getting some lively discussion going!
      I’ve had another look at it closely checking the features Raymond has pointed out and also checked in Skinner (a book that I haven’t used for a while but should do so more again). Listed in Skinner is the fact that Rivulet has a more distinct whitish central band on the hindwing, which, upon looking a my moth it does have. So I’m now with you Raymond, an unusual looking Rivulet, not Small rivulet. Will try and get photos of this feature for people to see.

  5. Raymond Watson says:

    Thank you Neil. There are two web sites that show a good selection for these two species, Norfolkmoths and Lepiforum.de. For anyone still not sure, thumb through the images there. It is often an error to use a single character to differentiate between two similar yet variable species. I note that Norfolk moths adds the word ‘usually’ for the sole difference often quoted at other locations.

  6. Paul Kitchener says:

    A single specimen like that, without a typical Rivulet in the same catch for size comparison, would quite easily go down as a Small (to be fair, there was no mention of size in Neil’s original post).

    • Neil says:

      I think that is what I would have identified it as if I didn’t have the other ‘normal’ Rivulet for comparison.

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