Do doctors ever use bugs for medical reasons?

As strange it may sound, both leeches and blowfly maggots are used occasionally in the field of medicine. The U.S. federal government’s Food and Drug Administration considers both bugs “approved medical devices,” the first live animals to be called that name. Maggots are used to eat dead tissue, thus helping to kill bacteria, clean open wounds, and stimulate healing. Leeches suck out excess blood from the body, and their saliva contains a powerful blood thinner. About 5,000 clean, laboratory-grown maggots are delivered to hospitals across the United States every week.