If you don’t fish and you’re not a regular on one of our big western limestone lakes – the likes of Lough Corrib, Mask, Carra, Sheelin and Derg – the excitement around “the mayfly” might seem a bit baffling. Think of it this way: it’s a sunny May evening, and a bunch of kids are happily playing in a playground, when suddenly someone bursts open a huge piñata and sweets rain down everywhere.