By the look of the picture and your description it appears to be what I call a bottle green Buzzer. I'm not at all sure of it's Latin name but in size and appearance it closely resembles a classic grey boy in it's pupal form but it takes on a dark green hue to the body as an adult and the legs can be anything from medium to golden olive. For the adult I use the hopper below, for an emerger I use either the hopper or a similarly coloured sugar cube buzzer and for a pulled wet emerger I use the spider below.
The tying for the hopper is as follows:
Hook: Hyabusa 752, size 10.
Thread: Roman Moser 8/0, black.
Post: Lureflash small booby eyes, red.
Body: A mix of black, black claret and dark sooty olive Seals fur.
Rib: Fine red wire.
Legs: Knotted Cock Pheasant tail dyed olive.
Hackle: Black olive Cock.
The Pulling Buzzer is:
Hook: Partridge YMM2A, size 10.
Thread: UTC 70 den, brown olive.
Body: Thread.
Rib1: Fine holo gold tinsel marked with Copic "ciao" marker, shade BG96"bush".
Rib2: Fine oval gold.
The body is then given a coat of superglue and 2 coats of HAN.
Wing buds: Tangerine Goose biots.
Hackle: Black olive Hen.
Hope this helps.
Dom. Most of the variations are sub species but I believe there is also some variance within sub species. It would take a taxonimist to properly identify all the variations.