According to the Dutch entomologists of EIS Kenniscentrum Insecten & andere ongewervelden today, this species had disappeared from Dutch river banks 79 ago because of pollution. In 1936, the last mayfly was seen where once there had been millions of them.
After the river water had become cleaner, in 1991 the first mayfly larva was found again in the Netherlands. Now, they are getting more numerous in some places along Dutch rivers. The adults are seen only in August.