Myiasis is infection with the larval stage (maggots) of various flies. Flies in several genera may cause myiasis in humans. Dermatobia hominis (Diptera: Oestridae) is the primary human bot fly; its distribution ranges from Mexico into South America. Chrysoma bezziana (Diptera: Calliphoridae) is the Old World screwworm and Cochliomyia hominovorax (Diptera: Calliphoridae) is the primary screwworm fly in the New World. 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.
Adults of the Human Bot Fly (Dermatobia hominis) are free-living flies. Adults capture blood-sucking arthropods (such as mosquitoes) and lay eggs on their bodies, using a glue-like substance for adherence. Bot fly larvae develop within the eggs, but remain on the vector until it takes a blood meal from a mammalian or avian host. Newly-emerged bot fly larvae then penetrate the host's tissue. The larvae feed in a subdermal cavity for 5-10 weeks, breathing through a hole in the host's skin. Mature larvae drop to the ground and pupate in the environment. Larvae tend to leave their host during the night and early morning, probably to avoid desiccation. After approximately one month, the adults emerge to mate and repeat the cycle.
