Greenbottle fly pupae (Lucilia sericata). Flies have four lifecycle phases, egg, larva, pupa and adult (imago). Larvae (maggots) of the greenbottle fly are able to clean wounds by eating dead, or dying flesh, and leaving healthy areas. The maggots prevent the growth of harmful bacteria in the wound by altering the acidity and releasing an antibiotic compound. This is a more efficient method for wound healing and prevention of gangrene or septicaemia than drugs or other treatments. Only this species of maggot, which is bred in sterile conditions, ais used for surgical purposes. Photographed at Zoobiotic, Wales, UK. This is Europe's largest supplier of surgical maggots.