Rajesh Chaudhury, an assistant professor, and Vineesh Kumar, a laboratory technical expert from the biomedical science department at the Acharya Narendra Dev College, Delhi, have spotted a rare species of butterfly called the dark cerulean thrice between October 2018 and February 2019 in two different places in the capital. The species was last seen in 1990. Prior to this, in August 2018, the duo had spotted a male member of the rare butterfly species, common lineblue. This rare species of butterfly was last seen in 1962 in Delhi. Their findings were recorded in Bionotes, an Indian quarterly research newsletter. According to lepidopterologist (those who study moths and butterflies) and researchers, the changing floral diversity of the city and changes in metamorphosis due to transportation of eggs, could be a possible reason for the birth and attraction of new species from nearby places.