americas, ranging from the cold temperate regions in the north, to corresponding latitudes in the south. myiasis is also not restricted to sheep; screwworm flies (cochliomyia hominivorax in particular) regularly cause upwards of us$100 million in annual damages to domestic cows and goats, though the impact has been heavily mitigated in recent years by the sterile insect technique. history myiasis in a cat's flesh myiasis in a dog's flesh frederick william hope coined the term myiasis in 1840 to refer to diseases resulting from dipterous larvae as opposed to those caused by other insect larvae (the term for this was scholechiasis). hope described several cases of myiasis from jamaica caused by unknown larvae, one of which resulted in death. even though the term myiasis was first used in 1840, such conditions have been known since ancient times. ambroise paré, the chief surgeon to king charles ix and king henry iii, observed that maggots often infested open wounds. maggot therapy main article: maggot therapy throughout recorded history, maggots have been used therapeutically to clean out necrotic wounds, an application known as maggot therapy. fly larvae that feed on dead tissue can clean wounds and may reduce bacterial activity and the chance of a secondary infection. they dissolve dead tissue by secreting digestive enzymes onto the wound as well as actively eating the dead tissue with mouth hooks, two hard, probing appendages protruding on either side of the "mouth". maggot therapy – also known as maggot debridement therapy (mdt), larval therapy, larva therapy, or larvae therapy – is the intentional introduction by a health care practitioner of live, disinfected green bottle fly maggots into the non-healing skin and soft tissue wounds of a human or other animal for the purpose of selectively cleaning out only the necrotic tissue within a wound in order to promote healing. although maggot therapy has been used in the us for the past 80 years, it was approved by the fda as a medical device only in 2004 (along with leeches). maggots were the first live organism to be marketed in the us according to fda regulations, and are approved for treating neuropathic (diabetic) foot ulcers, pressure ulcers, venous stasis ulcers, and traumatic and post-surgical wounds that are unresponsive to conventional therapies. maggots were used in medicine before this time, but were not federally regulated. in 1990, california internist ronald sherman began treating patients with maggots produced at his lab at the uc irvine school of medicine. sherman went on to co-found monarch labs in 2005, which uc irvine contracted to produce maggots for sherman's own continuing clinical research on myiasis at the university. monarch labs also sells maggots to hospitals and other medical practices, the first us commercial supplier to do so since the last one closed in 1935. in the us, demand for these fly larvae doubled after the fda ruling. maggot therapy is now used in more than 300 sites across the country. the american medical association and centers for medicare and medicaid services recently clarified the reimbursement guidelines to the wound care community for medicinal maggots, and this therapy may soon be covered by insurance. the larvae of the green bottle fly (a type of blow-fly) are now used exclusively for this purpose, since they preferentially devour only necrotic tissue, leaving healthy tissue intact. this is an important distinction, as most other major varieties of myiasitic fly larvae attack both live and dead wound tissue indiscriminately, effectively negating their benefit in non-harmful wound debridement. medicinal maggots are placed on the wound and covered with a sterile dressing of gauze and nylon mesh. however, too many larvae placed on the wound could result in healthy tissue being eaten, efficiently creating a new wound, rendering it as a type of myiasis. history maggot therapy has a long history and prehistory. the indigenous people of australia used maggot therapy, and so do the hill peoples of northern burma, and possibly the mayans of central america. surgeons in napoleon's armies recognized that wounded soldiers with myiasis were more likely to survive than those without the infestation. in the american civil war, army surgeons treated wounds by allowing blowfly maggots to clean away the decayed tissue. william baer, an orthopedic surgeon at johns hopkins during the late 1920s, used maggot therapy to treat a series of patients with osteomyelitis, an infection of bone or bone marrow. the idea was based on an experience in world war i in which two soldiers presented to him with broken femurs after having lain on the ground for seven days without food and water. baer could not figure out why neither man had a fever or signs of sepsis. he observed: "on removing the clothing from the wounded part, much was my surprise to see the wound filled with thousands and thousands of maggots, apparently those of the blow fly. the sight was very disgusting and measures were taken hurriedly to wash out these abominable looking creatures." however, he then saw that the wounds were filled with "beautiful pink granulation tissue" and were healing well. maggot therapy was common in the united states during the 1930s. however, during the second half of the twentieth century, after the introduction of antibiotics, maggot therapy was used only as a last resort for very serious wounds. lately maggots have been making a comeback due to the increased resistance of bacteria to antibiotics.