Mulesing is a routine surgical procedure done on sheep, particularly in Australia where most of the commercial wool comes from. It involves the removal of the skin from around the sheeps buttocks which is the area that retains urine and faeces and so attracts flies. Its is done to prevent infections but is a painful surgical procedure for the sheep. Public pressure to improve sheep welfare has led to the wool industry researching alternatives to mulesing. This is why mulesing-free merino wool items might cost a bit extra.