This moth had me puzzled for a good while, as I tracked up and down the three pages of 'Beauties' - more formally known as Geometridae (Ennominae) in the Moth Bible. The scientific name diverted me which didn't help my concentration; I wondered if it might be one of those curious fusions of Greek and Latin which sometimes came to Linnaeus. If so, could 'ennominae' mean 'un-nameable' in Latin and could that in turn mean that the great scientist shared my confusion?
Some hope! Thanks to a very good American and Canadian website called Bug Guide, I now know that the word is Greek and means 'just' or 'lawful', possibly because the Ennominae account for over half of the whole Geometrid family of moths. Geometrid comes from a phrase meaning 'to measure the Erath' and is thought to refer to the distinctive, bendy progress of the family's caterpillars which are commonly known as 'loopers'. I further found a very good little table showing the way that moth classification works. I append it here, partly for my own future use:
Kingdom: Animalia (Animals)
Phylum: Arthropoda (Arthropods)
Subphylum: Hexapoda (Hexapods)
Class: Insecta (Insects)
Order: Lepidoptera (Butterflies and Moths)
They leave it at that, apart from missing out the category 'taxon' between 'order' and 'superfamily' on the grounds that moths do not have one; the old term I remember from school - Heterocera as opposed to Rhopalocera for butterflies - is a Sub-order. If this subject intrigues you, Bug Guide has an excellent page discussing it here. But I think one could usefully add below 'family': 'species' and then 'form' or 'variety' which is where my puzzling over today's moth came in.
I was rescued by Peter Hall on the Upper Thames Moths Blog who identified it as a Mottled Beauty, and Dave Wilton on the same invaluable source of expertise who elaborated that it is form Conversaria, a type of Mottled Beauty which sports a distinctive black belt and has, he says, been notably widespread in the Oxfordshire and Buckinghamshire this year.
To salvage my self-respect, I also offer you a picture of a moth which I can identify, even though it is one of the small but infuriatingly similar Pug tribe. It is a Green Pug and I am not claiming brownie points for knowing that. Its greenie-ness gives it away.