Good point. I guess I call it a hatch, like fly fishers talking about a bunch of bugs coming out at once.
Since you seem to know a bit more about them, do they eat as adults or just reproduce like soldier flies? I recall hearing they lay eggs under bark. Is that correct?
Y'all should see them here. They can be 3-4" or so, much bigger than any I saw in the States. But they emerge every year, making noise but not enough to bug anyone (pun intended) and dont last long. There are smaller ones too, but Ive never heard them much. Strange creatures!