PolyU commemorates the International Day for Biological Diversity by staging an engaging sharing on 22 May 2019. Organized by the Campus Sustainability Office, a lunch talk themed ‘Butterflies of Hong Kong’ stunned the campus community. Mr. Hydrogen Pun, Advisor of Fung Yuen Butterfly Reserve, Tai Po Environmental Association, came to meet the campus community with detailed information on the common butterflies species found in Hong Kong. Participants grasped the opportunity and learned to distinguish the different species, know how they breed and what makes their homes. They enjoyed a lot in this interesting and interactive sharing and were invited to rethink how city dwellers could have affected the living of the butterflies. With these events, CSO aims to raise the awareness of the campus community over the importance of biodiversity and a healthy ecosystem, since the number of butterflies species has reduced significantly.