|One of the Tissues that came to light at Llyn Mawr|
There are several other records from around the county from upland areas where the foodplant is perhaps somewhat unlikely. It's possible the moth is able to thrive on isolated patches of buckthorn, existing in high enough density to wander from these areas.
But is it perhaps more likely this moth is utilising a different foodplant in the county? I notice Andrew Graham has made the same observation on his north Wales site, saying "Occurs on moorland, miles from the stated foodplants. Could it be breeding here on some other plant?". Text on the Yorkshire Moths website hints at their suspicion it might be feeding on something else in their county.
In addition to the two buckthorns, the Natural History Museum database gives ash, apple and bird cherry as plants it's been recorded on in continental Europe. I also find reference to it feeding on hawthorn abroad. Clearly elsewhere it's adapted to other foodplants - so why not here?
The only tree species growing nearby to where the moths were caught at all three sites is rowan. Could this be an alternative foodplant? It's just possible, I suppose. If Glaslyn is excluded, birch and willow are common to the two other sites. There are of course going to be plenty of low-growing plants common to all three sites.
Obviously this is just speculation but certainly an area that merits some attention. Next summer I'll try searching/beating rowan at these sites for larvae - probably worth a try! Hopefully I'll also obtain a gravid female and, if so, I will see if the larvae are less choosy in captivity and what other plants they will accept.