Green Pug.
(Pasiphila rectangulata)

This was my first attempt at identifying a Pug - a Green Pug.

Information:
Fore-wing length: 8-11mm. If it is bright green (and doesn't have a 'V' mark near the leading edge of the fore-wing) then it probably is a Green Pug.
They are very common and widespread throughout Great Britain. They fly June-August and can often be seen close to Apple, Blackthorn, Cherry, Hawthorn or Pear trees - the flowers of which the larva eat.