Răzvan Popa, László Rákosy, Andrei Crișan, Florin-Mihai Pop, Demetra Rákosy Abstract Pseudophilotes bavius ​​is a butterfly species protected by the EU Habitats Directive. The subspecies P. bavius ​​hungarica, known by the vernacular name Transylvanian Blue, is endemic to the Transylvanian Plain (Transylvanian Plateau) in Romania. Its distribution is limited to dry grasslands on steep, south-facing slopes, always in association with Salvia nutans. Unfortunately, many of the extant populations of P.bavius hungarica are threatened with