Mayfly
mayfly, the first three years of ignorance in the water, and then changing as Imago. Only life of one day, neither eat nor drink. So they have very lithe body, floating in the air.

They only do things is flying together choose marriage, spawning in hurry.

After mating mostly male died immediately, the female also died tired after spawning reproduction.

mayfly almost the same time a large number of deaths, falling water, just in a moment.