Green Flies

Last evening we saw what can only be described as a localised swarm of green flies. I'd say that they were just under 1cm in size and looked more like a mosquito than say a house fly.

Never seen such things in all the years we've been coming to Spain.
They seemed to be more attracted to one section of our white garden wall than anything else specific. Some were hovering, but most just attached themselves to the wall.


They vanished upon spraying them.

Just wondering what they were. From my description, could they have been a type of mosquito?

Are they, not quite ripe flies?