"That was in June, fish-fly season "

Fishflies are flying insects with lifespans of several years, but only live up to a week as adults (and only a day on land). Eggs are laid en masse on the borders of still water and larvae leave the water to pupate under bark for ten days. Fishflies hatch in Michigan around the beginning of June in a season that lasted for around three weeks in the 1970s but has lengthened in recent years. The postmating 'dancing' of fishflies in huge swarms and the subsequent mass of insect bodies requiring cleaning-up causes nuisance and they are also notable for their pungent odour.