Chrysomya bezziana, also known as the Old World screwworm fly or screwworm, is an obligate parasite of mammals. Obligate parasitic flies require a host to complete their development. Named to honor the Italian entomologist Mario Bezzi, this fly is widely distributed in Asia, tropical Africa, India, and Papua New Guinea. The adult can be identified as metallic green or blue with a yellow face and the larvae are smooth, lacking any obvious body processes except on the last segment. The fly feeds on decaying organic matter, while the fly larvae feed on the living tissue of warm-blooded mammals as opposed to necrotic tissue that many other fly larvae feed on. Since the larvae can cause permanent tissue damage, C. bezziana has led to much public concern. Management procedures include both prevention of colonization of the fly and treatment of a current infestation. Chrysomya bezziana belongs to the genus Chrysomya, which contains species like Chrysomya rufifacies and Chrysomya putoria. C. bezziana and other members of this genus can be used to estimate the post-mortem interval in forensic entomology. Geographical distribution Chrysomya bezziana is widely distributed throughout tropical areas in the Old World. It is most prevalent in Southeast Asia, tropical and subtropical Africa, some countries in the Middle East, India, the Malay Peninsula, the Indonesian and Philippine Islands, and Papua New Guinea. C. bezziana is not found at altitudes higher than 2500 meters above sea level. In countries where Chrysomya bezziana does not exist, scientists and those in agriculture are worried that commercial flights, boats, or vehicles will distribute the fly. The climates C. bezziana thrives in are present in Australia and the Americas; the fly requires climates similar to its New World relative Cochliomyia hominivorax. Spread of the pest from Papua New Guinea to Australia has become a concern for Australia, as the presence of C. bezziana could cost livestock industries up to $500 million a year. Characteristics Chrysomya bezziana belongs to the fly family Calliphoridae. This family comprises blow flies, carrion flies and cluster flies. Other parasitic screwworms are found in this family, such as Cochliomyia hominivorax and Cochliomyia macellaria. Adult The body of the C. bezziana adult is typically metallic green or blue. The face of these flies is typically yellow with soft fine yellow hairs. The length of an adult fly ranges between 8 and 12 millimeters. The abdominal tergites (the segments of the dorsal portion of