ITCH MITE INCIDENCE

Press, Volume C, Issue 29524, 27 May 1961, Page 7

ITCH MITE INCIDENCE

More Than 40 Properties Itch mite has been diagnosed on more than 40 properties since it was first diagnosed in Mid-Canterbury in 1953. Mr H. Doyle, the livestock superintendent of the Department of Agriculture in Christchurch, told the Lincoln College farmers' conference last week. The majority of cases had been in South Canterbury but this was probably due to the fact that more investigations had been carried out in that area by the departmental veterinarian at- Timaru than in any other areas. Infested sheep had also been found on properties in Mid-Canter-bury and Marlborough as well as other districts. As investigations proceeded in other districts where fine wool sheep were grazed Mr Doyle said that it might well be found that the incidence was as high as in South Canterbury. Discussing control measures, Mr Doyle said that lime-sulphur appeared to be the most effective material available to control itch mite. For total eradication, the only, effective method seemed to be plunge dipping or showering in lime sulphur solution containing 1 per cent, of polysulphides within a few weeks of shearing.

Unpleasant Lime sulphur was, however, ineffective against lice and keds. It was also unpleasant to use and was comparatively expensive. As the dip was an irritant to wounds, sheep should not be dipped off shears and given time to allow wounds to heal. Care had also to be taken that they did not inhale or swallow the dip. While arsenical dips did not totally eradicate itch mite, they appeared to effectively control the parasite and keep infestation sufficiently low that damage to the fleece was not evident if dipping was carried out each year. Arsenica idips were also effective against lice and if rotenone was included in the dip keds could also be controlled. These dips had the added advantage of being cheaper than lime-sulphur. Rotenorte had also been shown to reduce itch mite numbers but it was not considered as effective as arsenic. Gammexane, dieldrin, aldrin and diazinon appeared to be ineffective in controlling itch mite. Irrespective of which effective material was used, Mr Doyle said that it was essential that the fleece be wetted down to the skin. This could be done by the use of a plunge dip or a shower dip provided the sheep did not carry more than a month’s wool growth and every precaution was taken to see that the sheep were thoroughly wetted.. f