Since mayflies’ body sizes and lifespan vary between males and females, it is often difficult to generalize their life cycle. In addition, many different factors such as temperature and humidity come into play during each stage of their life. As a result, mayflies’ life cycle can take months to years.
This is because many species of mayfly spend time as immature larvae (called nymphs) or as aquatic larvae before they become adults and emerge into the air. When do these changes occur depends on their habitat and how restrictive it is. Then, they emerge from the water when they are ready to become adults and mate, lay eggs, and die.