I seem to have spent a lot of time this weekend seeking out Rosebay Willowherb (Chamerion angustifolium) in an attempt to find leafmines of Mompha raschkiella. It is Dean Stables's fault for publishing a photo on his blog! I'm also looking for Mugwort at the moment and Phyl Abbott (Plant Atlas of Mid-west Yorkshire) suggests that this often grows with Nettle and Rosebay Willowherb in unmanaged grassland.
On a nettle-patch between Jerrison Wood and Spring Wood at Esholt I saw the greatest concentration of Commas that I have ever seen in one place. There were also Red Admirals, Large Whites, Ringlets, Meadow Browns and Gatekeepers.
I will try to remember to return here at the end of August to search for Comma caterpillars which I have only ever found on elm.
I could only find vacated mines on the willowherb apart from one which seems to contain several tiny beetle larvae.
I will have to keep searching the Rosebay Willowherb in the hope of finding a tenanted mine.
Stopping the car by yet another stand of Rosebay Willowherb, near Menston, I noticed this Yellow Shell (Camptogramma bilineata).