Maggot: A soft-bodied wormlike larva of a fly that lays its eggs in living or especially in decaying tissues. The living or rotting material furnishes heat for the hatching of the eggs and food for the newly hatched maggots.
Certain blowfly maggots -- notably, those of the blackbottle fly (Phormia regina) and the greenbottle fly (Phaenicia sericata) -- were used in medicine to consume and clear away both bacteria and dead tissue from deep wounds and so promote their healing. This was a favorite part of the treatment of osteomyelitis (infection of bone) and other deep suppurative (pus-filled) lesions. In a sense it was biologic (rather than surgical) debridement of a wound. The maggots also promoted healing by secreting allantoin, a supposedly salutary substance found also in fetal urine.