Mark Benecke, perhaps the world’s most colorful forensic entomologist (and maybe the only one who is also the main character in a play) digs up the US Army’s advice about using maggots medically:
From the US ARMY SPECIAL FORCES MEDICAL HANDBOOK, ST 31-91B, Chapter 22 “PRIMITIVE MEDICINE,” Section 3: “MAGGOT THERAPY FOR WOUND DEBRIDEMENT.”
22-3. Maggot Therapy for Wound Debridement.
a. Introducing maggots into a wound can be hazardous because the wound must be exposed to flies. Flies, because of their filthy habits, are likely to introduce bacteria into the wound, causing additional complications. Maggots will also invade live, healthy tissue when the dead tissue is gone or not readily available. Maggot invasion of healthy tissue causes extreme pain andhemorrhage, possibly severe enough to be fatal.
b. Despite the hazards involved, maggot therapy should be considered a viable alternative when, in the absence of antibiotics, a wound becomes severely infected, does not heal, and ordinary debridement is impossible.
(1) All bandages should be removed so that the wound is exposed to circulating flies. Flies are attracted to foul or fetid odors coming from the infected wound; they will not deposit eggs on fresh, clean wounds.
(2) In order to limit further contamination of the wound by disease organisms carried by the flies, those flies attracted to the wound should not be permitted to light directly on the wound surface. Instead, their activity should be restricted to the intact skin surface along the edge of the wound. Live maggots deposited here and/or maggots hatching from eggs deposited here will find their way into the wound with less additional contamination than if the flies were allowed free access to the wound.
(3) One exposure to the flies is usually all that is necessary to insure _more_ than enough maggots for thorough debridement of a wound. Therefore, after the flies have deposited eggs, the wound should be covered with a bandage.