In a blue cape of newly minted wings, an adult male pursues mates. With streaming tails mayflies may reach five inches (12 centimeters) in length. Females molt just once to become adults, but males must do it twice. First they shed into the subadult stage. They remain in this stage only for a few minutes. The most vital development, that of the sexual organs, isn't complete until after the second molt, when males change their brown wings for blue ones. At this point they have only about three hours to mate before they die.