Myiasis is infection with the larval stage (maggots) of various flies. Flies in several genera may cause myiasis in humans. Cochliomyia hominovorax (Diptera: Calliphoridae) is the primary screwworm fly in the New World and Chrysoma bezziana (Diptera: Calliphoridae) is the Old World screwworm. Dermatobia hominis (Diptera: Oestridae) is the primary human bot fly. Cordylobia anthropophaga (Diptera: Calliphoridae) is known as the tumbu fly. Flies in the genera Cuterebra (Diptera: Oestridae), Oestrus (Diptera: Oestridae) and Wohlfahrtia (Diptera: Sarcophagidae) are parasites of other animals that also occasionally infect humans.
Cochliomyia hominovorax is a Neotropical species, ranging from Mexico into South America. Adult C. hominovorax flies lay their eggs directly in, or in the vicinity of, wounds on the host. Larvae feed in the host for about a week, and may migrate from the subdermis to other tissues in the body, often causing extreme damage in the process.