Field assessment of permethrin in the control of sheep headfly disease.

Three groups of sheep, gimmers, ewes with lambs and rams, were sprayed at fortnightly intervals from June to September 1980 with a 0.1 per cent emulsion of permethrin in an attempt to control damage caused by Hydrotaea irritans. Complete prevention of damage was not achieved but the number of sheep affected and the severity of lesions present in affected sheep was significantly reduced in comparison with untreated control groups. Permethrin treatment was also judged to be valuable in the management of rams with head wounds. Variation in susceptibility with age was noted, gimmers being the most severely affected and a breed variation was apparent in the rams which was related to the character of horn present.