Also known as the hawthorn fly in Europe. They like hawthorn trees. I used to fish a lake that had a large hawthorn tree on the shore. Around this time of year there would be lots of those flies bumbling around in it, and whenever the wind blew from the right direction they’d fall in the water. The trick was to stand around 50’ back from the bank so you couldn’t be seen, and cast a dry fly so that just the leader and the fly landed on the water.