Inventories on the butterflies at REGUA began in 2007 when Alexandre Soares, a professional entomologist from the National Museum in Rio de Janeiro, made monthly visits for two years before publishing a preliminary species list for REGUA.

In 2015, Alan Martin and Jorge Bizarro started work the fourth REGUA book A guide to the Butterflies of the Serra dos Orgaos. The book lists 803 species that occur in the area, plus there are at least 120 Hesperiidae (Grass Skippers). The book took five years to prepare and includes all the species that are known to occur according to previous publications, websites, unpublished data from researchers, but most importantly also from records and photos taken by visitors to the REGUA reserve and surrounding area. All but three of the species are illustrated either with photos of live specimens (from 75 contributing photographers) or where not available, using pinned specimens from the museums in Parana or London.

To date, 444 species (plus some Grass Skippers) have been recorded at REGUA, and it is certain that there are others still to be found at higher altitudes which have been recorded in similar habitats nearby. These include four species that have yet to be described; one metalmark, two satyrs and one skipper. Flight times are very variable and dependent on temperature, rainfall and altitude, but for lowland species the most species-rich months are April-June and the lowest diversity occurs in November-January, but higher altitude species generally fly earlier.

Only 55 butterfly species have been listed as Threatened in Brazil but work has yet to be completed on the hairstreaks, metalmarks and skippers, so the list is very incomplete. Four of these Threatened species have been recorded at REGUA, Mimoides lysithous harrisianus, Parides ascanius, Dasyophtalma rusins delanira and Eupthchia boulleti.

Download an addendum to A Guide to the Butterflies of the Serra dos Orgaos here.