The Tisa Mayfly (Palingenia longicauda) - is the largest mayfly species in Europe, males measuring up to 12 cm 5 inches) from head to tail. This long-tailed mayflies are aquatic insects which belong to the Ephemeroptera order. Their larval stage usually lasts three years. The adults are short-lived: once fully matured, they have roughly three hours to mate and then die.