The most serious pests that at the present time are threatening the great wool and sheep industry of Australia, are the sheep-maggot flies (blow-flies belonging to the genus Calliphora). Until about ten years ago blown wool on living healthy sheep was unknown, sheep that were worried and torn by dogs were blown, and rams that damaged their heads fighting might have to be dressed and cleaned of maggots, but the bush blow-flies had not until about that date acquired or developed the habit of depositing eggs or living maggots in the soiled or damp fleece of the ordinary station paddock sheep.