Wednesday, 18 June 2014

Costal Folds

Since I don't think you can add images to comments, I thought it would be easier to create a new post to show highlight the costal fold - a character I keep banging on about, as it can be rather useful with male tortricids. It is a sense organ on some males, and contains scent scales. So here is a close-up of Vaughn's Notocelia:
And here it is again with the fold highlighted:
On a good photo of a male Tortricid it can usually be seen. So here is an image of E. trimaculana on UK-Moths. The fold can be seen, and reaches nearly the middle of the wing:
I can't see a fold on the two rosaecolana photos, but on roborana:
and on incarnatana:
the fold is again reaching the middle of the wing - as it should according to Bradley et al (1979).
If you keep going through UK-Moths you will see some quite striking folds:
The costal fold was the key character indicating to me that this moth:
was Epiphyas postvittana, and not Clepsis consimilana. For the discussion check the original post (here). Essentially, the fold can be seen to about 2/5ths, whilst Clepsis does not have one at all.


  1. That's absolutely brilliant Dave. Thank you for taking the time to do that! It would be useful if this feature had been used in Clifton and Wheelers book on bird dropping mimics - I wonder why they didn't put it in...

    Can I ask another question? The bird dropping mimics book also refers extensively to 'fascias' of various types, (basal, median, subterminal and subasal) which is a term I'm not sure I fully understand. Am I right in thinking it refers simply to the relative position of blocks of colour on the wing, or is there something else to it? Hopefully that won't require a separate post to answer!

    1. I get the impression that there is a whole generation of moth'ers who are not familiar with the character, but I am working hard to promote it!

      As for fascia's - they are bands of colour that run across the wing - from the costa to the dorsum. Basal = near the base of the wing (ie nearest the body), median = middle of the wing, subterminal = near the termen (the edge of the wing furthest from the body. I guess sub-basal means nearer to the bosy than the basal fascia, but I'd need to look that one up!

      I'm sure I've seen good diagrams of what the parts of the wing are called and what the markings are called - possibly in Stirling/Parsons/Lewington?

  2. Yes thanks Dave - very interesting. I certainly wasn't aware of it so thanks for making it clear!

  3. A very interesting and useful post Dave.