Although much has been written about the life and especially the scientific work of René Jeannel, his interest in butterflies has not been mentioned at all. During his multiple excursions through the Carpathians, searching for caves and cave fauna, Jeannel has collected also some lepidoptera that he prepared, labelled, and grouped in an entomological case beside the coleoptera collected in Romania.
The majority of the butterflies have been collected between 1920 and 1925 during the expeditions, in which Jeannel has participated in different regions of speological importance in the Carpathians and the surroundings of Cluj. The oldest samples in the collection originate from the surroundings of Bucharest, and they were collected in August 1915; 15 samples bear the label " Şoroneşti", probably meaning " Şurăneşti", Vaslui county, the place of birth of his friend and colleague, Emil Racoviţă.
The Collection includes 142 species of macrolepidoptera belonging to 14 families, and a total number of 421 samples.