When raw meat rots, it becomes infested with maggots. The tiny white worms are larvae of flies that feed on flesh. While commonly seen in raw fish and meat waste, as well as decomposing animal and human remains, some doctors are putting maggots on open wounds of live trauma patients they treat. The surgical practice seems gross but surprisingly saves lives.

Polly Cleveland, of New York City, turned to so-called maggot therapy when her sick husband’s bedsores became wounds that needed cleaning, NBC News reported.

The bugs were sourced from modern maggot therapy pioneer Dr. Ronald Sherman, who raises them in germ-free laboratories. Cleveland placed the maggots on a piece of gauze contained in a vial into the wound, and the fly larvae ate the pus and other debris, leaving nicely cleaned tissue, according to NBC News.

With the diseased and dying tissue removed, wound infection is prevented.