Australian sheep breeders to continue selecting for the thickest possible fleeces on their sheep. This lucrative trait often meant that the thick, wrinkled wool on the sheep's rear readily attracted and held dirt and feces. This collection of unsanitary material as well as the skin ulcers it sometimes caused are very attractive to gravid female blowflies. Female blow flies seek out sheep with wounds and soiled wool to lay their eggs. Once the maggots hatch they gravitate to open wounds if any are present. This is flystrike, a type of myiasis. Flystrike, also called breechstrike, often leads to systemic secondary infections and death. In the early-1930s an Australian rancher named John Mules was shearing an ewe when he accidentally cut off a small patch of skin near the ewe's breech (buttocks). The ewe had suffered from flystrike before and Mules carefully watched her progress in case she developed another infestation in the wound he had accidentally caused. To Mules' surprise once the wound healed it replaced tangled and dirty breech wool with smooth scar tissue. Blowflies were no longer attracted to this area on the ewe as it could collect little dirt or feces. No relapse of flystrike occurred. Mules and others soon developed this into a technique now known as mulesing. During this operation small strips of epidermis are peeled from a sheep's buttock using steel shears on either side of the anus and underside of the tail. This was formerly performed on mature sheep but it was later found that lambs recover more quickly and completely than older animals. For lambs older than two months the period of greatest discomfort seems to last for approximately two weeks, by which time healing is almost complete. Current codes of practice ban mulesing for sheep over 12 months of age. Mulesing reduces the likelihood of flystrike by about 13 times. The practice became nearly universal during the 20th century. The success of animal rights movements in agitating for the procedure's curtailment has brought the proportion of Australian sheep ranchers who practice mulesing down to around 70% today. Successful international boycotts of Australian merino wool in the early 2000s set those invested in Australian sheep rearing on the hunt for alternatives. The publicity generated intense interest in finding a replacement for mulesing that domestic and international consumers will accept. Method Mulesing is a procedure which, in Australia, is carried out by a