I understand that non-odonatologist easily mix up dragonflies and damselflies with mayflies, that live just one day as flying insect. The fore wings of a mayfly is much larger than the hind wings and the wings are kept vertically while resting, the antennas are large and at the tail has two or three long feelers.
Swedish mayflies live as larvae in the water for one or two years.
As winged insect the mayfly can't eat, therefor their life is short, sometimes as short as a few hours, but some species can live almost one week. Dragonflies and damselflies live much longer. As larva in the water the Swedish dragonflies live normally between 2 and 4 years, but in northern Sweden they might be larvae as long as 10 years, due to the cold and dark climate. Damselflies live as larvae 1 to 3 years, except for sympecma fusca that live as larva only 8-10 weeks. When the dragonfly or damselfly has hatched to flying insect it lives a very dangerous life, some birds love dragonflies for dinner.