Insect manoeuvres

I'm not sure what these insects are (some kind of midge?), but found lots of them arranging themselves like some sort of display team on the undersides of every leaf on one of our garden trees. Later, having watched a little of the BBC programme 'Airport Live' I thought they were a bit like the aircraft parked around the terminal buildings, seen from above. Entertaining thoughts on a day when I couldn't get out for a decent walk in the countryside.