A novel dip formulation of a synthetic pyrethroid (SP) for the control of blowfly myiasis of sheep.

Field trials were carried out during the summer months of 1994 and 1995 to ascertain the prophylactic effects of a 10% w/w formulation of a synthetic pyrethroid (Ecofleece, Cross Vetpharm Group Ltd.) against sheep blowfly myiasis (fly strike). The trials were carried out on the same three farms each year. The flocks, of mixed breeds, comprised between 500 and 700 sheep. Treated sheep which consisted of ewes and lambs were plunge dipped, with at least one complete immersion. At least 10% of each flock were left untreated to act as sentinels. Both sentinel and treated sheep mixed freely at pasture. All recorded cases of fly myiasis were treated by topical applications of the same formulation. Inspections of the flocks were made daily by the farmers and weekly by one of the investigators. Prophylaxis against blowfly myiasis was achieved for periods ranging from 3 to 9 weeks. On some occasions, fly larvae developed in faecal dags but failed to establish on the sheep or cause lesions.