Rhogogaster scalaris
This was swept from Birch. I keyed it to Rhogogaster viridis using the RES key and momentarily got quite excited when I saw how few records of viridis there are. My excitement was tempered by a vague recollection that there has been some revision taxonomy or nomenclature, and sure enough it turns out that the species called viridis in that key is in fact Rhogogaster scalaris - probably the commonest member of the group!
female Rhogogaster scalaris showing forewing, hindwing, head from in front, head obliquely from side/above, top of abdomen and saw teeth, Wendling Beck Environment Project (Norfolk, UK), 27th May 2025