Mayflies have been around for some 350 million years. This means that they existed even before the dinosaurs came to existence and they survived extinction event that wiped out the dinosaurs.
Nymphs are aquatic and that live under water for nearly 2 to 3 years. During this time, they undergo about 20 or transformation phases.
Adult Mayflies do not have a well-defined functional mouth. This means that they cannot eat. Simply put, adult Mayflies do not eat. They live for a very short span and their only purpose of survival at this stage is reproduction. Once they reproduce, they die. Some species will last only for 24 hours in the adulthood. The shortest lifespan is seen in the species known as Dolania americana where the adult females survive for just 5 minutes.
Because Mayflies are short-lived, they are collectively known as Ephemeroptera (it is the order and the scientific name). Ephemeroptera is basically derived from Ephemeros – a Greek word meaning ‘lasting a day’. This is the reason why Mayflies are also known as one-day insects or one-day flies.
Mayflies can only survive in clean water environments. They cannot live in pollution. The presence or absence of Mayfly larvae is an important indicator of water pollution.