Yellow-barred Grass-miner Elachista gangabella

Formerly given the vernacular name Yellow-barred Dwarf.

A scarce species in Norfolk, or at least one that is rarely caught. The individual shown below appears to be the first adult to have been found in Norfolk for at least 50 years (and possibly ever - the older records do not specify if they are adults or not).

The single bar across the forewings of this moth was immediately interesting as none of the Elachista species that I have had previous experience of share this feature. It is shared by a couple of other scarce species (Woodland Grass-miner Elachista obliquella and Yellow-edged Grass-miner Elachista bisulcella) but these have contrastingly pale cilia at the wing-tips which are lacking on gangabella. The fascia looked more white than yellow but did have a slight yellowy tint and this was much clearer when examined under a microscope. The cilia were a little worn but I was reasonably sure they were uniformly dark (the pale in the cilia showing in the second photo below is reflection from the microscope's light), but to be on the safe side the genitalia were examined. I didn't do a very good job of preparing the slide but I think you can just see enough (and I certainly could before I placed the cover slip on) to confirm it as gangabella. The shape of the juxta is probably the most important character but the shape of the valvae seems to differ slightly between the three species too.

male Yellow-barred Grass-miner Elachista gangabella showing dorasl view under microscope and genitalia (aedeagus separately), Wendling Beck Environment Project (Norfolk, UK), 24th June 2022