Along the Thames at Kingston I'm watching mayflies lifting off the surface on weakly fluttering gossamer wings to begin their ephemeral lives of barely a day.

For those fortunate enough to reach the safety of the bank, they will perch and undergo a final moult to become perfect insects called spinners (pictured)

A few hours later they will join an evening nuptial flight with scores of others flying up a metre or so then parachuting down rhythmically until a partner is found. Their mouthparts are useless as there is no time or need to feed again.

Once mated, males die, leaving females to fly back to the river to deposit their eggs.

When laid, females collapse onto the surface, wings spread-eagled, to be sucked down by surface feeding fish such as dace and bleak.

But, as many lift off from the river their already brief lives are snuffed out in an instant as swallows; swifts; starlings; sparrows and pied wagtails pluck them out of the air to enjoy a rich feeding bonanza.

Although living for only a day as adults, mayfly nymphs spend up to three years on the river bed feeding on detritus and plant material.

On chalk streams, whenever a mayfly hatch is in full swing, trout go crazy and indulge in a feeding frenzy.

Fishermen call this time 'duffers fortnight' implying that any novice angler cannot fail to hook a fish as he casts his artificial mayfly onto the stream.

The mayfly. Such miniature beauty, but such transience