The Tisza mayfly is the largest mayfly species in Europe, males measuring up to five inches (12 cm) from head to tail.
The Tisza Mayflies
or 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. Male Tisza mayflies are unique among the winged insects in that they molt one more time after acquiring functional wings. This second-to-last winged instar is usually a matter of minutes.
Typically, all Tisza mayflies mature at once, and for about a week in mid June, they will be everywhere after 5.00-6.00 PM, dancing over the river in large groups, molting on trees or on the ground, or resting on every available surface, including onlookers. This natural phenomenon with varied intensity is called Tisza blooming.
Once they fully mature (after their second molting into a winged state), males have only a few hours to find females and mate before both sexes die. Squadrons of mature males will skim over the river's surface, seeking females.
After mating, the female mayflies start a compensation flight up the river, to ensure that the eggs laid on the river will sink down to the bottom at the place where their parents emerged. After about 45 days, the eggs hatch into larvae, which remain buried in the mud for three years, until they emerge and molt into adults.
The mayflies are pollution-sensitive animals, thus if they are in or around the water, the water should be of a good quality.
Besides being environmental indicators, the mayflies are also a favorite food of many fish, and consequently a favorite bait used by fishermen. Despite their protected
state, illegal collection of the larvae occurs, therefore nature-lovers who come to observe the Tisza blooming will also see National Park staff, the Water Police, and other organizations patrolling the river to safeguard the mayflies. According to the law, mayfly specimens cannot be collected, neither alive nor dead
The long-tailed mayfly has become extinct in several countries of Europe, and the Hungarian population is also endangered by the pollution of the Tisza. Come prepared in June, stand still by the river, and don’t shriek when they land in your hair. Watch from up close, as a male mayfly molts on your arm, and experience the drama in these humble, fragile insects’ life. Let it sink in, and understand why we need to protect them.
"Nimfea" Environment and Nature Conservation Association