They're slimy, squiggly, and they eat dead tissue. But they're not some creature from a horror movie — I'm talking about maggots. Maggots — as in the worm-like larvae of flies? Why are we talking about them? Because they're good medicine!

They were approved as a prescriptive therapy in 2004 and have been used to cleanse wounds for thousands of years. Surgeons in Napoleon's army noticed soldiers whose wounds were infected with maggots were more likely to survive.

During the American Civil War doctors deliberately put maggots into wounds letting them consume dead decaying flesh without affecting healthy tissue. Eventually maggot therapy fell out of favor when antibiotics came out.

But not so fast ' fly larvae are still used today and the practice even has a fancy name: biosurgery. Maggots are extremely effective in treating diabetic patients with open sores on legs and feet that have stopped responding to antibiotics. They're also able to consume infected areas that surgeons have trouble seeing and removing. An average application of sterile maggots can consume ten to fifteen grams of necrotic tissue per day.

Anything they consume, including bacteria, is liquefied and destroyed, so that healthy cells can move in. Maggots also change the pH in the wound, and their secretions contain proteases, which are enzymes that degrade proteins in the tissue, including those that cause inflammation.

Even so, much about how maggots work in wound healing remains a mystery and needs further study. What's apparent is this archaic therapy is resurging as an effective medical tool, sometimes in cases where antibiotics no longer work.