Musings on mystical mayfly

MAY is the high point of the year for the fly fisherman. People with no interest at all in fishing have heard of the mayfly and the excitement it inspires in fish and fishermen when it makes its annual appearance.

The reason for the excitement is there is a large group of insects from many different families that spend most of their lives under water and then emerge, sprout wings and spend a short period, varying from a few days to a few weeks, flying around and mating, quite a lot of them in May.

Why should so many species of insect, from huge dragonflies to tiny midges, have evolved to spend part of their lives under water and part of them flying around in the air? The answer to the question seems to be that life under water (almost exclusively fresh water) seems to offer great advantages when it comes to feeding and growing bigger. But it is necessarily a rather sedentary life style which is a disadvantage if you want to inspect a large number of potential mates. The mobility of the flying insect facilitates the maximum dispersal of genes.