How do a lovelorn insects find a mate?
There are various strategies, but one of them is to gather in a mating ball or mating swarm. Such swarms abound at this time of year, hanging over fixed references such as a tree or post, or marshalling along the edge of a sunbeam.
In the swarm the insects perform a dance which involves flying to the top and floating down. When they find each other, they will mate in the air.
A mating swarm of mayflies had anchored itself along the edge of a sunbeam.