I live within a block of the lake. There are early hatchers, there is the bulk of the main hatch, and then there are some that hatch late. I have one or two on my slider screen many mornings in the late summer/early fall.

I suppose a late(er) hatch would beget another late hatch the following year as these bugs lay their eggs on the water.

PS - I'm not an entomologist, nor do I play one on TV.