An investigation of ewe to lamb transfer of the itch mite Psorergates ovis

Abstract

Extract

The life-cycle of Psorergates ovis is completed in 5 to 6 weeks and there are six stages — egg, larva, protonymph, deutonymph, tritonymph, and the male or female adult. All stages are found under the stratum corneum but adults and occasional tritonymphs are also found on the surface of the skin. Only the adult is motile and is responsible for spread of infestation, mainly while fleece is short (Murray, 1961). Observations on successful transfers of infestation have been made on sheep held in pens for long periods — i.e., up to a year (Graham, 1943; Roberts et al., 1965). Unsuccessful attempts to observe transfers between long-fleeced sheep held in pens for up to 9 months have also been reported (Graham, 1943; Davis, 1954).