The use of fly-traps for the control of sheep blowfly strike was examined on 12 commercial sheep farms in south west England in 2003. Two flocks acted as controls, with no prophylactic blowfly strike control. Four flocks of lambs and three flocks of ewes were protected only by blowfly traps, seven of the flocks of ewes and six flocks of lambs were protected by blowfly traps but also had proprietary insecticides applied to them at some stage. There was no difference in the abundance of L. sericata at the various sites. The highest incidence of strike was seen in the two control flocks where 10.9 and 5.8% of the ewes and 10.1 and 9.2% of the lambs were struck. Strike incidence in the flocks that used trapping only and flocks that used trapping plus a chemical preventive was on average five times lower than in the control flocks, but the percentages struck on the sites in the trapping only and trapping plus insecticide groups were not significantly different from each other. The results of this study show that traps can make an effective contribution to blowfly strike control on individual farms.