[Effectiveness of a PVC ear tag impregnated with the insecticide flucythrinate]

A PVC ear tag containing the synthetic pyrethroid flucythrinate was tested in seventeen herds including 218 heifers. There was a comparable control group of twelve herds including 157 heifers. The ear tags were more effective against sucking flies than they were against sticking flies. Varying with the species of the fly, the effectiveness ranged from 36.2 per cent to 95.7 per cent. The effectiveness also varied between the herds. The active constituent was still released within approximately 5 1/2 months after introduction.