Dr. Norman D. Penny of the Department of Entomology, California Academy of Sciences, spearheaded this Webpage to provide an online world checklist of extant mecopterans (scorpion-flies and hanging-flies). An updated version of the world checklist published by Penny & Byers (1979), this online list is intended as a reference for biologists and naturalists interested in mecopterans. The list is organized by Family (from Apteropanorpidae through Panorpodidae) and includes descriptive characters for each Family, full scientific names for each species, and a handful of color images of some select species.